Banjo

The most likely part of the ECU over system; where noise can be "induced", into the system, is at the COPs, themselves; right at the top of the engine. C.O.P.s commonly have a common return line to chassis ground, which serves both the +12V supply that charges the primary of the C.O.P. ignition coil, & the return line for the +5V trigger pulses. There seemed to be little I could do in this area, as it was widely acknowledged on the net, that it is a major source of trigger signal degradation. It was then, I discovered that there are C.O.P.s that have a separate return line for the +5V trigger pulses. They are used on late model V6 Commodore & GMH vehicles. I purchased a new one on line, & it does work admirably. It is an ICON brand with P/N IGC-277M. This provided the ability to separate the +12V supply return, & the +5V trigger pulse return line. However, I did notice, when I placed a multimeter between these two returns, that it was not an open circuit. There was a resistance between them, of exactly 10K ohms. Puzzled over this, & then asked Gogle A.I. Why is there a 10K ohm resistance between the two +12V & +5V trigger signal, return lines, on an ICON model IGC-277M C.O.P. ignition coil, when I was led to believe they were completely separate from each other. Here is A.I.s Answer: The 10K ohm resistance you're measuring between the +12V power supply and the +5V trigger return (ground) lines on your ICON IGC-277M ignition coil is a standard feature of its internal "Smart Coil" architecture. While these lines appear "separate" in a wiring diagram, they are internally linked for circuit protection and signal stability: Internal Pull-Down Resistor: The IGC-277M uses a 10K ohm pull-down resistor to ensure the trigger signal remains at a solid 0V (ground) when not actively being fired by the ECU. This prevents electromagnetic interference (EMI) from causing "ghost" sparks. Integrated Igniter (Smart Coil): Because them IGC-277M is a Coil-on-Plug (C.O.P.) unit with a built-in power transistor, it requires a shared reference point to switch the high-current 12V primary based on the low-current 5V trigger. The 10K resistance is the path your multimeter sees through the internal switching circuitry. Protection against Back-EMF: This high-resistance path protects the delicate 5V ECU driver from the massive 12V inductive spikes (back-EMF) generated when the coil's primary field collapses. Open Circuit Detection: Many modern ECUs use this specific resistance to monitor the "health" of the coil. If the ECU sees an "open" (infinite resistance) or a short, it can trigger a misfire code (e.g., P0351–P0356). Note: If you measure significantly less than 10K (e.g., <100 ohms), the internal igniter is likely shorted. If you see infinite resistance, the internal trigger circuit is "open" and the coil will not fire. __________________________________________________________________________________________ However My 4 off +5V trigger signals leave the shielded 4 off twisted pair cable & enter the final module via 4 off opto-couplers, so there is no signal or ground return line. I then decided to produce a +5V power supply for providing the 4 off P Type MOSFETs to provide the power to the trigger inputs on the C.O.P.s. You can obtain little 12V DC to 5V DC isolation module, where there is no connection at all between the ground of the ingoing 12V supply; & the ground of the outgoing 5V supply. Then I discovered, that the +5V output was not regulated. After a lot of research & experimentation, I decided to obtain a 12V to 9V isolator module, then feed the 9V into the input of a precision LM2940 +5V regulator, which will supply the P type MOSFET switches (TC4424). The +5V trigger pulses are not "hungry", in terms of power/DC current required, so the TC4424 P Type MOSFETs are fine, & are what are fitted to the Speeduino ECU. So that is it, basically, & it is all working on the bench perfectly, with a 4K head & four spark plugs. Just need to tidy it up a little bit, before I connect & install in on the 5K engine. Cheers Banjo

The next part of my extra modules & modifications, after the ignition signals have been produced by the ECU; were processed to be either in waste spark, or sequential format; was to address the area where the four C.O.P. trigger signals, leave the "safe confines", of a shielded metal ECU case, & head out across 1 - 2 meters of space in the engine compartment; to the C.O.P.s on the top of the engine. Four (4) little 5V pulses, just 3-4 m/sec wide, in a "hostile" environment, that is full of electrical noise, that can be picked up, & which results in distorting the shape & timing of these critical C.O.P. trigger pulses. The wiring of these C.O.P. trigger signals could simply be carried out, by placing the signals in a shielded cable, where the "shield" in connected at the ECU end only, to a good chassis ground. I decided to go two steps further. One was to isolate the four signals completely from each other, by placing eight (8) opto-couplers; one at each end of each trigger line. In addition to that the four pairs of wires in the cable are twisted pairs. That allows any induced signal into one wire would also be induced into it's return path, & they would cancel the noise out. This virtually makes the path across the noise hostile path to the COPs; noise free, & results is the four signals arriving at the C.O.P.s as good, or better, than when they left the ECU. They should/could be better; as all eight (8) opto-couplers have hysteresis switching built in, which results in their rise & fall lines, being extremely sharp. (very important) as the rising edge, in particular, carries the timing information to each C.O.P. Next time, I'll describe the final block, to provide the power required to these four (4) =5V trigger pulses with P type MOSFETS, right at the head of the engine. I have been concerned, that a few of my techniques may be a bit over the top, & too far fetched. I sent a longish enquiry to the Google A.I. site, & asked what it thought of my design. It advised that everything I'd done, including the high speed logic I.C.s would provide the system, (end to end) the very best chance of being almost totally "noise free" Cheers Banjo

The Sequential / Wasted Spark logic switch, took a little longer to produce. The idea was simple; but the turning it into hardware, took a few tries, to get it right. The brief to myself was to take the four (4) off ignition pulses from the Speeduino; & then produce the same four pulses, in the correct firing order; in either sequential or wasted spark mode. Sequential, has been; & still is, the preferred way of operating the ignition system in modern vehicle engines; primarily as emission standards in most developed countries stipulate that. However, in theory, wasted spark operation, particularly when starting & cranking the car; should find C.A.S. pulse synch earlier, & therefore start the engine more quickly. A search on the web, using A.I. found that a number of modern car manufacturers do; exactly what I was theorizing; by starting the car in wasted spark mode, then switching to sequential, once it is running. It's hidden deep inside these vehicles ECUs, & no one would even suspect that is happening, every time the engine is started. The starting was very simple, as when You turn the ignition switch on, you twist it that little bit further to place the switch in the “start” position. I simply picked up this signal which normally drives the starter motor starting relay, & fed that to the “Switching Logic Module”, via an Opto-coupler. (12V signal in, & 5V logic signal out.) As soon as the engine starts, & you release the ignition switch start position, the logic switch automatically reverts back to sequential ignition mode. However, I also wanted for my own interest; a switch on the dash, so I could switch the engine ignition mode from Sequential to Wasted Spark mode; so I could see if I could detect any improvement in particular driving conditions & engine loads. Again, this dash switch would be electrically isolated from the 12V system, via an opto-coupler. There was also an “OR” function built in, so that the Sequential to Wasted Spark mode switch would take place, from both a start switch “or” a dash switch. I started out using "fixed logic" for this switch; changed to a single processor integrated circuit, requiring programming; but eventually simplified the hard logic model, with some very fast logic chips. The outputs of this module, already now had the firing order required built in. It is simple then to attach the four (4) C.O.P. trigger signals, to the right C.O.P. Simply; 1 to 1; 2 to 2; 3 to 3; & 4 to 4. The circuit appoints the correct sequencing. Cheers Banjo

I want to describe each block in yesterdays sketch, so You can understand the logic, of why I have headed this way. In truth, You don't really need any of this additional electronics. The four ignition outputs from the Speeduino will drive the four (4) COPs without too many issues. However the Speeduino ECU, just produces four (4) pulses in a row, & has no particular firing order, built into the sequence of those four pulses. It is up to the installer to connect the four (4) ignition outputs, 1,2,3 & 4, to the appropriate ignition coil or C.O.P., based on the firing order; which in our case is 1 - 3 - 4 - 2. In other words . . . Speeduino Ignition O/P#1 to C.O.P. 1 Speeduino Ignition O/P#2 to C.O.P. 3 Speeduino Ignition O/P#3 to C.O.P. 4 Speeduino Ignition O/P#4 to C.O.P. 2 The distributor is where this all starts; as it provides a string of evenly spaced pulses per revolution, which is actually equal to two revolutions of the crankshaft. A distributor with a 24 pulse output, is equivalent to a crank mounted trigger wheel with just 12 off teeth or magnets etc. They both produce 24 pulses per 720 degrees rotation of the crankshaft. I settled for the distributor to produce the trigger pulses, as it the easiest way for anyone get started, with this exercise. Take an olde Bosch produced K series distributor body, & gut it, & fit an optical punched disk assembly from a Nissan, Daewoo, or Mitsubishi engine, & you are away & running quite quickly. The added benefit for me, was if while I'm road testing this system, & it breaks down, or it just stops: I can very quickly revert to an original dizzy, & get back home. However, by using a cam driven dizzy, we are introducing the "wavering" of the C.A.S. (Cam Angle Signal/Sensor), as a result of the "slop" & "wear", in timing chain; sprockets & helical gears; & belt flex/stretch in twin OHV engines. Earlier in this thread I described the first block in yesterday's block diagram; labelled the "Distributor Processing Interface". Basically, it logically produces a C.A.S. pulse when a single pulse from the crankshaft, coincides with the wider C.A.S. distributor pulse, once every two revolutions of the crankshaft. The two outputs of this "Distributor Processing Interface", are then feed into two (2) opto couplers, which are a device that uses a infra-red light source inside the MOC-5007; such that the input terminals & the output terminals are completely electrically isolated (no common ground circuit). In addition, the MOC-5007 opto-coupler has hysteresis built into it's switching, which guarantees a very sharp clean transmission between the On & Off parts of the signal. ((basically, is switches on, at a slightly higher threshold voltage, than the voltage at which it switches off. eg: On a 0-5V signal it might say switch on a 4V; but not switch off, until the signal gets down to say 2v. This leaves a 2V dead-band in the middle of the switching band. I've made full use of opto-couplers at several places in this circuit, & oscilloscope checks of the final +5V pulses, arriving at the trigger inputs of the four (4) off working C.O.P.s; indicate very clean & sharp pulses. These resultant pulses are fed into the RPM1 & RPM2 pulse inputs on the Speeduino ECU, which certainly won't need the assistance of any VR Conditioner; to produce clean sharp pulse to the micro-processor. ( Oh, I hate those VR sensors) This Distributor Processing Interface actually has a total of 5 off Opto-Couplers on board. Three (3) off isolate the pulses coming into the board from the trigger pulse & CAS pulse from the dizzy, whilst the third isolates the single C.A.S. pulse from the crankshaft pulley. Tomorrow; I'll describe the Sequential/Waste Spark switch block, & opto-coupler stage, before the four (4) C.O.P. trigger signals are sent on their merry way, out into the engine bay; on-route to the four (4) C.O.Ps (Coil On Plug) mounted on the engine. Cheers Banjo

Been a few weeks, since I introduced the "switching on the fly"; & on cranking, of the Speeduino ECU ignition outputs from "Sequential' to "Wasted Spark"; & visa versa. I then pointed my attention & efforts to another area of ECU operation, that has been of great interest to me; & that is regarding "noise"; & how it can cause havoc in ECUs, operating in a very "electrically noisy environment. In the real stationary world, we have our feet standing on the earth, & electrical noise can be directed to ground. In a vehicle, with rubber tyres, that is not possible; although You will be aware of the straps that rub on the roadway, under the car, & remove static charges in the vehicle frame, which are apparently are a source of dizziness & motion sickness etc. Apart from the early car radios, that were prone to picking up noise from the cars engine operation, there was not much else that was affected. The ignition systems were mostly 12 volts, & any inference could be eliminated by a capacitor fitted to the offending electrical device. Then along came electronic controls, in their droves; to both engine & general lighting, & A/C controls. The problem with modern electricals, when fitted to automobiles; is that they rarely are powered by +12 volts. +5V is common, & microprocessors in ECUs, can often operate of DC voltages, as low as 3.3 volts DC. To some extent; the ECU itself, can be mounted in a metal enclosure or box, & suitably earthed to the chassis frame, to protect it from "radiated noise" that passes through the air, like a radio wave. However, once wiring to & from sensors & actuators in the engine bay are wired back to the ECU, then the noise is introduced to the ECU, via this cabling. Now it is possible to wire up every sensor & actuator attached to the ECU, via "shielded" cable, & the shield connected to the chassis ground; & this will obviously assist. However, the chassis ground or zero volts is not the earth. It is an artificial floating ground plane. So here we have a ground frame in the car carrying enormous currents (100s of amps) during say "cranking the engine" on a cold morning; along with tiny / minute currents from sensors & the likes, that ECU needs to read accurately, to base it's controls upon. The starter motor commutator & brushes are one issue, known to us all; but there is another one, much more intrusive. "Spark Plug discharges". Unlike the starter motor, that is only used during starting the car; (remember how olde cars used to turn the radio off, (whilst the ignition switch was in the start position) the spark plugs are constantly creating arcs & electrical airborne noise, whilst ever the engine is running. Luckily, the actual spark occurs inside the engine, which creates a "protection metal shroud" from the actual arc itself. However, the coil or C.O.P. that produces that 20-30Kv spark, is out in open air. Anyone who has opened the bonnet, on a dark night; of an olde engine, running a dissy cap with HT leads across to the spark plugs, would be well aware of the coronas, visible across leads & H,T, carrying devices. So we move on, & the advent of the C.O.P.; & now we have a coil primary & secondary winding, along with a +5V DC trigger signal, sharing a common ground connection. I'm really surprised, that C.O.P.s work as well as they do. I was however, pleased to find, I'd been "hiding under a rock"; & that there are now C.O.P.s with a separate 5V return wire; to the chassis ground, for charging the primary of the H.T. coil inside the C.O.P. The one I have recently purchased, is an ICON, model IGC-277M. There are several ways we can resolve this problem of electrical noise being induced into the 12V system. Most ECUs, & their sensors, are powered by +5V; but share the ground with the 12V system. Enter the fully isolated DC to DC power supply, with a + 12V input, & a +5V output, but completely electrically isolated ground circuits. I've gone a bit overboard, by adding three off these to my Speeduino system, as depicted in the hand sketch below. Next post, I'll describe how I have used opto-couplers, to totally isolate one part of the system, from another; as well as using totally "shielded" twisted 4 pair cable, across that electrically noisy/hazardous path/journey from the ECU on the fire wall, or under the dash; to the four (4) C.O.Ps. on the engine itself. I've actually used a total 13 off opto-couplers in the circuit, plus 2 off for the signals from the ignition starter switch & dash switch, to change the spark control from sequential to waste spark, on the fly. Any questions or queries, please add to this post. Cheers Banjo

Update on the logic to switch ignition (& injection) on the fly. The Picaxe 14M2 programable microprocessor needs interrupt inputs for the four (4) trigger pulses, from the Speeduino ECU. Unfortunately, I found the 14M2 only has three (3) interrupt inputs. I upgraded to the 18M2+ Picaxe 18 pin micro, which has seven (7) off interrupt inputs. It worked well, but there were minute time differences between the time the pulses entered the micro, & when they left. This would not be discernible at low speed revolutions; but could induce small changes to the timing, at higher RPM. For that reason, I returned to the fixed logic I first started out with, but refined it; & utilised high grade CMOS HC logic integrated circuits, with hysteresis built in. The hysteresis produces very sharp edges on the output pulses produced, which reduces chances of any noise issues. The "AND" gate IC I used was a 74HC7001 (4 x AND gates), along with two off model 74HC7032 (4 x OR gates). The full circuit is depicted below, for anyone that wants to build it themselves. It worked out nicely, using all but one "OR" logic element in one of the "OR" ICs. Note that the common firing order for a 4 cylinder engine of 1 - 3 - 4 - 2 has already been incorporated in the design. The Speeduino ECU for which I am using this, does not have provision for allocating or programming the firing order. It simply outputs 4 off ignition pulses, in succession. It is up to the installer, to wire the four (4) ignition outputs to the correct cylinder. Any questions, just give me a yell. If You are questioning whether there is any point, or good reason, for adding this wasted spark/sequential switch; consider what A.I. had to advise about it, when I questioned it. Question to A.I. Are there any advantages in cranking / starting an automobile ICE engine in waste spark mode, & then automatically switching to sequential, once the engine has stated ? Yes, starting an internal combustion engine (ICE) in waste spark mode before automatically switching to sequential mode is a common strategy used by many modern Electronic Control Units (ECUs) Advantages for Starting Faster Synchronization: Wasted spark mode only requires a signal from the crankshaft to begin firing. Sequential mode requires identifying whether a cylinder is on its compression or exhaust stroke, which usually necessitates waiting for a full camshaft revolution. Firing in waste spark mode allows the engine to start as soon as the crank sensor is synced, rather than waiting for the cam sensor. Improved Starting Reliability: Firing twice per cycle (on both the compression and exhaust strokes) increases the likelihood of ignition during the first few rotations when air/fuel mixtures may not be perfectly homogenous. Fail-Safe "Limp Home" Mode: If a camshaft position sensor fails during operation or at startup, the engine can regress to waste spark mode to remain functional. Spark Plug Cleaning: The "wasted" spark during the exhaust stroke can help clean the spark plug by burning off any leftover fuel or oil vapor, which is particularly useful during cold starts. Benefits of Switching to Sequential Once the engine has started and the ECU has confirmed the camshaft position, switching to sequential ignition offers several advantages for long-term operation: Increased Coil Lifespan: Sequential mode fires each coil half as often as waste spark mode, reducing heat buildup and extending the life of the coils. Better High-RPM Performance: Because coils fire less frequently, they have longer dwell times (charge times) between events. This is critical for high-boost or high-RPM engines where maintaining a powerful spark is necessary to prevent "spark blowout". Precise Individual Cylinder Tuning: Sequential ignition allows the ECU to trim ignition timing for each individual cylinder, leading to smoother idling and better overall engine efficiency. Reduced Emissions: Eliminating the extra spark in the exhaust stroke and optimizing timing per cylinder helps reduce emissions, which is why most modern OEMs use sequential systems for standard operation. I liked the point in A.I.'s response, regarding limp mode, if you lose a C.A.S pulse, resulting in the engine stopping. I could detect C.A.S. failure & automatically switch to Wasted Spark, & bring up a warning light on the dash ? I'm tempted; bt must get this project "on the road". _______________________________________________________________________________________________ As a result of A.I.s answer to my previous question, I then asked A.I. the following question. What auto manufacturers have included an ecu feature for their engines, where the ignition, & injection (if applicable); start the engine is waste spark mode, & then switch to sequential operation, once the engine is running ? Question 2: Do any of these ECUs have a feature, where if the C.A.S. (camshaft angle sensor) fails, whilst driving; that the engine automatically switches to waste spark, & a warning light, or error message is produced by the ECU ? Many modern automotive manufacturers and aftermarket ECU providers utilize specific startup and fail-safe logic involving wasted spark and sequential operation. 1. Manufacturers with Wasted Spark to Sequential Start Logic Several manufacturers use a strategy where the engine initially fires in "wasted spark" mode (firing every 360° of crankshaft rotation) until the Camshaft Position Sensor (CAS) provides a sync signal, at which point it switches to full sequential operation (firing every 720°). General Motors (GM): Many LS-series engines and older Delco-based systems (like those in Buick and Chevrolet) use this logic. They initially fire in a "batch" or wasted mode to ensure a quick start and then transition to sequential once the cam phase is identified. Nissan: Various RB and SR series engines with factory ECUs are known to use a "limp-to-start" wasted spark logic if the cam signal is not immediately clear. Ford: Older EEC-V systems and some modern "dumb coil" applications (like certain Coyote Mustangs) can operate in wasted spark or sequential depending on the trigger setup. Aftermarket Manufacturers: Many high-end aftermarket ECUs explicitly include this feature to improve starting speed: Haltech (Elite/Nexus series): Allows for wasted spark startup and automatic transition to sequential. Link ECU (G4+ and newer): Can be configured to start in wasted spark and switch to sequential once the cam sync is achieved. 2. CAS Failure & Fail-Safe Modes Most modern ECUs include "fail-safe" or "limp home" logic to handle a Camshaft Angle Sensor failure while driving. Automatic Switch to Wasted Spark: If the CAS fails while the engine is running, many ECUs (such as Link ECU and Bosch-based factory units) will continue running by switching from sequential to wasted spark ignition. Since the crankshaft sensor still provides engine speed and TDC information, the engine can maintain operation, though with less precision. Warning Indicators: Check Engine Light (MIL): A CAS failure will almost universally trigger a "Check Engine" light or an error code (e.g., P0340). Limp Mode: The ECU may limit RPM or boost (in turbocharged cars) to protect the engine, as it can no longer accurately monitor individual cylinder timing or variable valve timing (VVT). Start-Up Behavior after Failure: If the CAS fails before starting, many systems will not start at all because they cannot determine the initial firing order. However, some systems are programmed to "guess" the phase or attempt a wasted-spark start by trying both phases until the engine fires. Cheers Banjo

On pages 6 & 7 of this thread, I noted my interest in providing a switching mechanism, to my system; that allowed it to be switched between Sequential & "Wasted Spark" mode during the starting procedure. Starting an engine in sequential, can take up to 2 revolutions of the crankshaft, before the ECU receives a CAS pulse. I would also like to be able to manually switch the engine firing (& injection) mode, to "Waste Spark" manually; whilst driving under different conditions; to see if I can discern, any difference in performance; under different real road load conditions. I was able to produce the logic to achieve this, using 5 off dedicated logic ICs, as depicted in an earlier post. Works perfectly, but unhappy, that I need "real-estate" on my printed circuit board for 5 off dedicated integrated circuits (ICs). As the logic itself, is pretty simple; I was interested to see if I could program the logic, into a small dedicated programable microprocessor. It was successful; & I used each & every pin on a 14 pin Picaxe 14M2 micro, which are commonly used for education purposes. However, they can be run at up to 32MHz, so are no slouches. They are only a few dollars each, & can be programmed in a free editor program, using "basic" commands. In fact; the program only required eleven (11) lines of code. As I stated earlier in this thread; the Speeduino setup does not provide for setting up a firing order, in TunerStudio. It has 4 off ignition outputs, & four of Injector outputs, which simply fire in order from the board, as 1,2,3,4 . It is up to the person, wiring up the system, to connect the 4 off ignition outputs to the correct cylinder coil &/or injector. In a "K" series engine. Ignition No: 1 Output to cylinder No: 1 Ignition No: 2 Output to cylinder No:3 Ignition No: 3 Output to cylinder No: 4 Ignition No: 4 Output to cylinder No: 2 I was able to include this firing sequence, into the code, so that whilst installing the system, the firing order is imbedded. Ignition No: 1 Output to cylinder No: 1 input Ignition No: 2 Output to cylinder No:2 input Ignition No: 3 Output to cylinder No: 3 input Ignition No: 4 Output to cylinder No: 4 input The other concerns I had, was ground/chassis/earth noise, particularly for the +5V pulses required by the DENSO COPs. Although the DENSO COPs, are a 4 wire connection, there is only a single wire "trigger" input for the +5V pulse. The return line is shared with the ground/chassis connection, for the +12V supply, for the COP. The single chassis ground connection, also handles the large coil primary charging current. I can & am using a tiny opto coupler (model A817) to fully isolate the output of my control system, from the DENSO coil. However, the fact remains, that the COP primary coil & 5V trigger signal, both share a common ground. I have thought about using a "fully isolated" DC to DC converter, to produce the +5V voltage ? There are ignition coils manufactured in the world to the IGN-1A standard, which provide 5 pin connection, with a separate ground connection, for the +5V signal return; to overcome this problem I mentioned above. However, my searching, as yet; has not found one in a COP format. Common 5-Pin Wiring Configuration For coils like the IGN-1A, the 5-pin connector typically follows this noise-prevention logic: High-current Battery Ground (Ignition Power Ground). Low-current Signal Ground (Reference return to ECU). Battery Positive (+12V Power). Trigger Signal (5V or 12V pulse from ECU). High-current Battery Ground (Secondary/Chassis Ground). I happen to like the DENSO COPs, as all my other Toyota vehicles use them (Corolla/Yaris/Echo/Camry) If anyone is interested in replicating, what I've done, then drop me a PM, & I'll provide you with the code. I can also code PICAXE 14M2 for You, & forward that, for the cost of the micro. Any questions or concerns; please give me a yell. Cheers Banjo

Hi Jasper, I've never used one; so cannot personally advise good or bad results. In this case, I turned to Google A.I., which scans all available information on the internet, to make it's conclusions, or suggestions.

We are starting to show our age, when we get into that era ! I guess you've read this following history, at one stage. https://www.secret-classics.com/en/drive-toyota-celica-ta22-st/ Others may like to. True story ! I was working on contract in PNG, in the highlands. I had a girlfriend, who had bought an imported RA40 hatchback, in that deep bronzy brown colour. It was Her pride & joy ! Just like this one pictured. Note: I did however, love the later series of this model, which featured a "Mustang" like rear tail area. https://carbuzz.com/toyota-ford-mustang-copycat/ She returned to Cairns, where She was living. When it was time to "go finish"; I flew to Cairns, where She was waiting at the airport. She had her bags packed, & the very next morning, we drove Her RA40 down to Brisbane, & later to Sydney, where we married. Yes, we drove away from the wedding reception, in the RA40. In subsequent years, we drove it all over Australia. One trip was a two (2) day dash from Adelaide to Sydney, overnighting in Broken Hill. It loved the wide open spaces, & with a 5 speed gearbox, never felt like it was at it's limit. Never let us down. I think there was once on a trip along the Murray, it was playing up; & I diagnosed it as a fuel pump issue. Hobbled into the local Toyota agent at Mildura, or somewhere; & they had a repair kit. Drove to a park, & fixed the fuel pump, on the side of the road. There were; (& are still) a very reliable vehicle. The hatchback was great ! You could lie the back seats down, & the "boot" area, plus back seat You could actually sleep in, unless You were over 6 foot tall. Cheers Banjo

Cheers Banjo

I asked Google A.I. the following questions.

Hi Jasper, Seems like You have checked everything, but the car being quite olde, there are a number of issues. If You go look on the internet, it does turn up a few possibilities, for your Daihatsu. ____________________________________________________________________________________________________________________________________________________________ If a 1982 Daihatsu Charmant LE fails to idle properly after all standard manual tests have been performed, the issue typically stems from specific aging components or internal carburetor failures that are not easily detectable through standard diagnostic routines. Hidden Carburetor and Fuel Issues Because the 1982 Charmant uses a carbureted system, standard tests may miss internal mechanical wear: Clogged Internal Idle Circuits: The fuel path for the idle circuit is highly convoluted, often traveling above the fuel level in the float bowl before descending. If the car has sat with old fuel, these internal passages can clog in ways that surface cleaning or "blowing through" cannot fix. Worn Needle Valve Tip: Microscopic wear on the needle valve tip can allow fuel to leak past into the engine, causing a rich mixture that cannot be corrected by the idle mixture screw. Malfunctioning Economizer Valve: If the idle is too rich and cannot be leaned out via adjustment, the economizer valve may be feeding fuel into the engine incorrectly. Sticking Automatic Choke: On older carbureted engines, a choke that is even slightly sticking or misadjusted will disrupt the air-fuel ratio enough to prevent a steady idle. Vacuum and Air Leaks Standard manual checks often focus on visible hoses, but hidden leaks can be more subtle: Carburetor Base Leak: Vacuum may be leaking around the base of the carburetor or through worn-out gaskets rather than the hoses themselves. Intake Manifold Gasket: Worn or damaged gaskets can cause a vacuum leak directly at the engine block, which is difficult to see without specialized testing like a smoke test. Clogged EGR Valve: Carbon buildup inside the EGR valve or its passages can cause stalling at idle. Mechanical and Ignition Timing Ignition Timing "Out of Whack": Even if set to manual specs, wear in the distributor or on-board computer components can cause timing to drift, resulting in a poor idle. Worn Valve Seals or Piston Rings: In older Daihatsu models, worn internal engine components can lead to reduced performance and erratic idling that external adjustments cannot fix. ____________________________________________________________________________________________________________________________________________________________ Hope somewhere in amongst that, You spot something, You've not checked as yet. Having had a couple of 4K engines, the Intake manifold gasket leaking, is quite a common issue. I'd be taking off both inlet & exhaust manifold together, & then run a straight edge across them. As it's been happening for some time; You may even see evidence of the leak, with discoloration of the metal surfaces, each side of the gasket. Let us know, if any of these suggestions, bring your idling issues to a sucessfull resolution. Here is a post on this forum, written 15 years ago, where the issue, I'm suggesting was discussed. https://www.rollaclub.com/board/topic/38875-4k-intakeexhaust-gasket/ Cheers Banjo

Hi Gino, Welcome aboard ! Many members on RollaClub run aftermarket ECUs, of various types; but You are the only person, who has advised they are running a Speeduino; & a V0.4 at that. I haven't actually got any road miles under my belt as yet, with my Speeduino. All my experimenting, with various trigger systems, has been on the bench. My Speeduino, will be running my 5K initially, which is a running working test engine, on a stand in my garage. That will be to prove the synchronizing of overlapping CAS signal, with the crankshaft single pulse per revolution. I've had it running on the 5K a while back, & then it was off to bench, for lots of triggering experimentation. Then it will transferred to my KE-30 2 door sedan. As I won't then have a test Speeduino, on the bench, to further experiment with; I've recently finished a Speeduino V0.4.3d. It is a nice ECU, as it's board is 30% smaller than my V0.3.7 Speeduino. The V0.4.3d has Bluetooth & idle control, so looking forward to that. This is what it looks like now, as this week I hooked up a 40 screw down block, so that all 40 pins on the Speeduino V0.4.3d, can easily be hooked up. Interested to know what type of triggering system you used, & how You implemented it. Post some pics of your setup in the your car, with some details of the setup, including ignition coils or COPs etc. I'm presuming that it is currently controlling "ignition only" ? I've actually got a second test engine in my garage, which is a 4K with a 7KE fuel injection setup. That will be the final step, so a lot more fun, & learning, before I get to that point. Cheers Banjo

Further to my post yesterday, I should warn, that what I'm doing, may not work for everyone, as trigger signals to various industry COPs, can vary in voltage & polarity. The COPs I am using are Denso 4 wire COPs, widely used in current & recent Toyota model Corollas, Yaris & Echo vehicles. The fourth wire I am not utilising; as it is a feedback signal to the Toyota factory ECU, to indicate whether a COP has fired correctly or not. Most COPs, are triggered by a +5v pulse from the ECU. However, there are COPs that apparently use a 0V pulse. There are apparently; also COPs, in the world that use a +12V signal. I discovered this by doing a bit of research last night, on Google AI. Here is what I asked, & how Google A.I. replied. Do all COP (Coil Over Plug) automotive ignition coils trigger off a +5V DC signal being applied to them, by the ECU; or do some brands use a negative going pulse, to trigger them ? No, not all Coil-On-Plug (COP) ignition coils trigger off a positive 5V DC signal . While a 5V positive pulse is common, other triggering mechanisms exist across different vehicle makes and models. The specific triggering signal depends on the coil's design and how the ignition amplifier (ignitor) is integrated into the system: Integrated Ignitor (3 or 4-wire coils): The majority of modern 3-wire and 4-wire COP systems have the ignition amplifier built directly into the coil assembly. These typically receive a low-voltage 5V trigger pulse (usually positive-going) from the Engine Control Unit (ECU). The coil fires when internal electronics are signaled by this voltage pulse. External Ignitor (2-wire coils): In older or different systems using 2-wire coils, the switching (triggering) is done by an external ignition amplifier module or directly by the ECU's internal driver. In these cases, the signal wire from the ECU/module essentially provides a negative-going pulse by grounding the primary coil circuit to build a magnetic field, then opening the circuit to induce high voltage (the primary voltage briefly drops close to ground potential before skyrocketing when the circuit is opened). The voltage spikes on this primary negative side can reach several hundred volts. Other Voltages: A few vehicles might even use full charging voltage (approx. 12V) as the trigger signal amplitude, though this is less common than 5V. Ultimately, the required signal type and voltage level are specific to the vehicle manufacturer and the particular ignition system design. -------------------------------------------------------------------------------------- There is another easily fixed issue with the polarity of the narrow pulse emanating from my listed circuit. I added four (4) opto couplers to the circuit in yesterday's post. The MOC5007 opto coupler has a open collector output, which means it pulls the output low, (to ground/chassis potential). I advised that the Denso COPs accept a +5V pulse, to start the COP charging the primary coil inside. This is easily fixed. The little MOSFET ignitor module I depicted in the previous post, have a positive & a negative terminal & an opto coupled input, to the MOSFET circuit. If the trigger signal, to charge the COP coil is +ve; then connect it to the +ve input terminal on the MOSFET module & tie the -ve terminal to ground. If the trigger signal, to charge the COP coil is -ve going; then tie the +ve terminal to +5V, on the opto coupled module, & the -ve terminal to the output of your circuit. P.S. There is one glaring flaw with my suggestion above. By simply reversing the polarity, of the opto-coupler connections, the width of the resulting pulse will be much greater, & does not allow intelligent COPs, to cease charging the coil, when saturation is reached. In the case of the Denso COPs, I am utilising; this betwen 3-4 m/sec. Cheers Banjo

The dual MOSFET ignition output drivers, for powering COPs & external coil ignitors, (model TC-4424), are mounted on the Speeduino PCB. I therefore cannot use these for triggering the 4 off COPs, so the Speeduino PCB, remains "unmolested". The outputs of the four (4) off 4075 ICs, on my switching module, are highly unlikely to have enough current capacity, to trigger the COPs. I therefore used external MOSFET opto isolated modules, to switch the four (4) off COPs. I've hooked up the outputs of my Sequential to Wasted spark switching module, to four (4) off these small MOSFET modules. That's the MOSFET on the LHS, & the little IC on the RHS; is the opto coupler. These are available on ebay, & are very economical. I paid $ 1.62 each, off memory. You can even purchase a dual version of these, with two (2) MOSFETs mounted on the one PCB. For about $ 8.00, You can have four (4) MOSFETs, to switch your four (4) COPs, or ignitors. However, the dual ones, don't appear to have opto-couplers, for the input signal. I might just add four (4) opto-couplers to my switch module output, so that it doesn't matter if the MOSFET module used; does not have an opto-coupler built-in. The Opto-Coupler I generally use, is the MOC5007. This Opto has "hysteresis" built in, which makes the system, I've created; very "noise tolerant". The beauty of the both MOSFET modules, I depicted above; that they both have a little LED on the board; so You can see that a signal is being received from Sequential to Waste Spark switching module. I've only been able to find one aftermarket ECU that incorporates Waste Spark functioning, during cranking. That's the high end MaxxECU race ECU. Apparently, LINK ECU mentioned way back in 2021, that they were considering including it; in a future upgraded specs; but I don't believe that has been implemented as yet. Cheers Banjo

Good news on the "start engine" in Wasted Spark mode; & drive in sequential, there after. It appears that a Speeduino ECU, can only be changed from Wasted Spark to Sequential; or visa versa; by changing the mode of operation in the project file setup screens, within TunerStudio. There appears to be no way to change it, "on the run/fly". Well I'm pleased to advise, I have my Speeduino, running on the bench, in sequential mode; but can switch it in & out of "wasted spark" mode, at will, on the run. This was done, without making any modifications to the Speeduino, whatsoever, or changing it's setup tables. The olde dissy cap, with four High Tension leads & plugs, never really had an issue, with timing or starting, as the rotor button in the distributor, will always fire the next spark plug & cylinder, in the sequence, irrespective of where it is, in the two revolution cycle; or where in the cycle, the engine finally came to a halt. With COPs, & no rotor button, & four (4) COPs under direct control of the ECU, there is a better way of possibly getting the engine to fire earlier; (in the first rotation of the crankshaft), while cranking. Start the engine in Wasted Spark ! The solution was quite simple. Take the four (4) ignition outputs from the ECU, (IGN1, IGN2, IGN3, IGN4) & run them through a set of logic gates, which pass them through as "Sequential", or convert them automatically to "Wasted Spark", as a result of an external signal, supplied by a switch on the dash, possibly by the extra wire on some TPS sensors, or instigated by the start position in the ignition barrel. When You hold the ignition key in the spring loaded position, whist cranking the engine; this signal can apply the extra signal to the logic gates to create two outputs for each sequential input. ie: When the ECU supplies a signal to fire cylinder no: 1, then the logic gates are set, so that COPs 1 & 4 fire together. When the ECU supplies a signal to fire cylinder no: 3, then the logic gates are set, so that COPs 3 & 2 fire together. When the ECU supplies a signal to fire cylinder no: 4, then the logic gates are set, so that COPs 4 & 1 fire together. When the ECU supplies a signal to fire cylinder no: 2, then the logic gates are set, so that COPs 2 & 3 fire together. The Speeduino ECU has four little LEDs, indicting sequential or wasted spark mode. In Sequential mode, the ECU simply fires the four (4) Ignitions outs one after another. IGN1; IGN2; IGN3; IGN4. It's up You, or the installer; to have to wire the four outputs to the appropriate COP, or external Coil Ignitor. I've hooked up four (4) LEDs, on the output of the small logic gate PCB, & I'm sitting here watching the LEDs on the Speeduino ECU board, in individual sequence, & that replicated on the logic board LEDs. However, as soon as I provide the additional logic signal to the small logic gate PCB, the four (4) LEDs on small logic board,; instantly change to 1 & 4 on together, & 2 & 3 on together. There is no delay; it happens instantly. Here is the logic circuit, if anyone wants to replicate this. No micro-processor, or programming required. Speed or frequency is not an issue. There are just 4 off "integrated circuits" (ICs) involved, that can be purchased at any electronics store, like Jaycar; for about $5-$6 total. The whole thing is powered by 5V DC, which will come from the ECU. A small 12V relay, powered by the start position on the ignition key switch, should be used to switch the +5V signal, to the logic board. I might add an opto-coupler there, with hysteresis built in; so there is no chance of "chattering" contacts, from a relay. Just have to wait now, until this is all in the KE-30, & I can try it out, on the road. Cheers Banjo

I did a little exercise late yesterday, & asked Google AI, to find me pictures or photos of Toyota engines, in which the distributor was depicted. AI duly supplied many ! I had a look through them, & came to the conclusion, that Toyota would have been happy if the engine did not have a distributor at all; as the dizzy location always seemed to be an "after-thought". Granted these variety of engines for RWD vehicles were used in later model vehicles, where they were adapted to FWD cars, but the "dizzy position", did not appear to gain a lot of attention. The K series engine had perfect positioning. Halfway along the block, on the sloping back side of the engine. If, for instance; the K series were ever to be modified to fit in an engine bay, for a FWD car; the dizzy would be facing the radiator, with good access & cooling. Toyota seemed to often have lots of self-inflicted issues; when designing position of dizzies; always fitting dizzies, close to very hot exhaust headers & extractors, & the like. Big burnt holes in the dizzy cap, were quite common ! Cheers Banjo

Don't want to "butt in" on this wonderful conversation, but I could not help myself, when I did a "double take", when I saw this picture, of a distributor on a twin overhead cam Toyota engine. Was this someone's attempt to remove the dizzy altogether, from it's factory position; too close the exhaust manifold; where the "bakelite" dizzy top, got too hot, to the point of breaking up ? Cheers Banjo

Hi David, Is your dash instrument cluster, similar or like this one I found on ebay, that has a number of photos, including the rear ? https://www.ebay.com.au/itm/326234860459 Cheers Banjo

Yes, The Toyota TPS sensor, which apparently was utilised on Camry & Corolla vehicles, definitely has 4 wires. I know I played with it a bit, when I received it, after buying it on line; but couldn't quite work it out. That did not concern me, as I wasn't going to use it, anyway. However, I did wire it up, with 4 wire cable, so I have the idle wire, that I could play with, & add a piggy back board, as it is already on the 4K-U engine. Not sure that will do what I want; as if I use that to "start the engine", it will drop back into "waste spark mode", every time, You pull up at a set of traffic lights, & take your foot off the accelerator. I really need it only during the engine "starting process". If You research it, a lot of countries will not allow vehicles with their engines running in waste spark format. Apparently, this is because of emission regulations, as waste spark, produces slightly higher emissions than sequential operation. Apparently, there were other factors that came into it; especially for the Americans, with a preponderance of V8 & 6 cylinders engines. The dual HT output coils used on GMH vehicles here in Australia, were widely used, & very popular. Simon / TAZ used them on his K Series engine. No rotor button, or dizzy cap with individual spark plug leads. I've always believed in sequential control, as You can tune each cylinder slightly differently, & pick up & control "knock" in an individual cylinder. Apparently, cost comes into it also. No CAS signal required from the camshaft. You don't even need a separate crank angle sensor. Just use a 24, 36, 60, or 72 toothed crank wheel, & remove one or two teeth, to become your crank angle sensor. Super simple; super cheap ! Initially, I will be using my ECU, as ignition only. My technique, whilst starting the car, has always been the same. Never have to use the choke, here in Qld. Before turning the ignition key, two quick pushes of the accelerator pedal, to activate the pump squirt function in the carby, to enrich the first suction cycle of the cylinders. Then I press the accelerator slightly (to open the throttle butterfly; & turn the ignition key to the start position. Perfect starts, every time ! I'll have a play with the TPS, later today, but I don't think it would work for me, in my situation. With COPs, it should be easy, as I'd only be redirecting the Ignition trigger outputs 1 or 4, to fire COPs & 1 & 4 together. Signals on ignition trigger outputs 2 & 3, would switch fire COPs 2 & 3 together. Remember, with COPs, I'm only talking about redirecting 5V DC trigger signals, as each COP, has it's own ignitor within/onboard. I'll try it here on the bench, with the Speeduino ECU & four spark plugs. I'll let You know how I fare. If You haven't worked me out yet; I just "love experimenting", & seeing whether ideas are "goers"; or "dead ducks". You'll never know, unless You try it out. Here is what AI dug up, about the pros & cons of Waste Spark, & Sequential ECU control: Here is what AI produced regarding emission standards requirements. Cheers Banjo

My KE30 2 door Corolla, has always been a very fast starter, since I installed my very first electronic basic ECU; which was a Jaycar project, from back, nearly a decade ago. Many people who have seen my car, have remarked how quickly it starts. It still has that Jaycar ignition system installed, (but not for much longer). The triggering is an olde K Series Denso dizzy with the springs & bobs weighs all removed, & the shaft "locked up". The points were removed, & in their place, I fitted one of those Hall Effect sensors, with an ignitor built in. I described it back in this thread, that Graeme started, way back in 2017, when His daughters Rolla was going through points regularly. https://www.rollaclub.com/board/topic/73743-electronic-distributor/#comments My setup was possible, because our ignition switch, has a start & a run position. In the start position, the starter relay to drive the starter motor solenoid, is activated, & the "ballast resistor" in series with the coil is effectively shorted out. The rotor button directs the HT from the coil to the very next cylinder's spark plug, in the "timing format". The Jaycar module was not in circuit, during the starting process, & the timing was the static timing, of 10-12 degrees BTDC. I would like to do a similar thing with my Speeduino ECU. However, not running a rotor button & distributor cap & leads, the best You can achieve is start the engine in "wasted spark" mode. I believe some modern day cars use this technique. However, I'm not sure whether the Speeduino ECU has the capability of carrying out this action. I'm currently awaiting an answer on that question. However, it may well be possible, using the start position on the ignition key switch, to close a relay, that mates up the paired cylinders in "Waste Spark" mode. (1 & 4) & (3 & 2) I'll try a couple of experiments on the bench here, & see if it is possible. P.S. When an engines stops, it usually comes to a spot in the 720 degree rotation, that is in one of two spots. I asked Google AI about this, & this is what it came up with . . . . Cheers Banjo

Hi David, It's a sad story with fuel level sensors in olde Corollas. They are not particularly accurate or linear, in their display. I've tried all sorts of things over the years. Best bet is to find something similar, that will fit in your tank, with it's float; & then massage the resistive signal at the dash end until it reads close to what it should. The single biggest problem I've come across with these fuel gauges, is the DC power supply regulator, fitted to the back of the dash unit. They regularly burn out. a regulator is required, as the 12 volt supply can go up & down, & the gauge would like increase of decrease. The regulator, is usually a 6, 7, or 8 volt DC one. I'd pull out the dash, & with the fuel sendor unit disconnected; measure the DC supply, with a multimeter, at the dash. I think I covered this in more detail once, somewhere on here. I'll see if I can't find it, & add a link in my reply. https://www.rollaclub.com/board/topic/76685-cleaning-inside-of-fuel-tank/page/2/#comment-723267 Cheers Banjo

Many of You; like myself, spent yesterday afternoon, watching the final Supercar race, for the season; in Adelaide. There was a lot riding on the result, & the big question was whether Broc Feeney could pull it off. It was not to be, & He was devastated, during his interview after the race. His car was not performing well, & He'd had a similar issue during the race the previous day (Saturday). https://www.supercars.com/news/supercars-news-2025-broc-feeney-technical-issue-adelaide-grand-final-engine-sensor-triple-eight https://www.supercars.com/news/supercars-news-2025-triple-eight-suspects-repeat-broc-feeney-saturday-misfire-engine-issue-explained-grand-final It was suspected that the issue was a misfiring engine, due to the VR or Hall Effect crank angle sensor, which is fitted at the rear of the engine, & apparently picks up it's signals from a toothed ring, mounted in front & adjacent to the flywheel starter teeth around the edge. I've been playing with Hall & VR sensors for some time now, & have never had a failure. I did a bit of searching on the nett last night, & there was some interesting, if not confusing data. There were statements that the Supercars used VR sensors; while other articles stated Hall Effect. Maybe, there is a mixture of sensors utilized ? You would assume; that as Broc's team had experienced the fault during Saturday's race, that they would have changed it out automatically, overnight. Maybe regulations made that messy or not practical ? My reading this morning, indicates that some Hall Effect sensors are "temperature sensitive". This guy in the UK, found that that is; & can be an issue. https://www.youtube.com/watch?v=kAOlPEnuTMw I've always fitted mine down on the crankshaft pulley at front of the engine. Altezzaclub, has advised me that rally cars usually don't like fitting them on the crankshaft, as if the engine is mounted north/south, then the crankshaft pulley, is in the danger zone; as sticks/stones/dust & debris, often finish up is area. However the Supercar engines all being V8s, there would be a lot of heat, in the area the sensor is fitted, from the exhaust headers & pipes; which no doubt glow red during the race. Could not find a photo or picture of it on the nett, but presume, is is probably similar to this picture. I was interested to find in my reading, that SuperCars all run in "waste' spark mode, rather than "sequential". This surprised me, as I would expect you would need sequential operation, if you were tuning each cylinder to the "n"th degree, to get the most out of it. It also stated that they are not allowed, uder the regulations, to fit a CAS sensor or signal. They still need a signal, to determine the position of the crankshaft, so the teeth or openings on the ring adjacent to the flywheel ring gear, must have one or two holes or tabs missing. No doubt there will be more discussion on this particular event yesterday, in the days to come, & some of answers to the questions I've posed & pondered, will be answered. Please add to this topic, if You are aware of an answer to some of my unknowns. Most VR or Hall Effect sensor pulse outputs in ECU controlled engines, use "pattern recognition" expectation, & can signal or substitute, if a pulse does not appear. I'm interested, as I'm not sure, at this point in time; whether the Speeduino ECU I'm using is sophisticated enough, to have those timing pulse fault detection features. I will pursue. I'm also guessing, if Supercar race engines only run i waste spark mode; that the flywheel mounted punched hole or tab gear is in a 60-1, 60-2, or 72-2 format. I'd like to be able to start my K series engine in waste spark mode; & then switch to sequential once it is running. This makes starting quicker, as it only needs one revolution of the crankshaft, for the ECU to know it's position, whereas waste spark, can require up to 2 revolutions, to gain the same positional information. Please add, answers You have to questions I've raised, above. A very interesting subject. Cheers Banjo

Hi Graeme, Thank You ! Well it took me a while to find this MCM video You mentioned. The video, is less than a week olde ! https://www.youtube.com/watch?v=Z34a0estBNI I believe this is it. The bit about modifying the dissy, is right at the very end of the video. It appears Marty got the bits He needs from a "Timmy" in Japan, from I6 Industries. I stopped the video when He got to the point of holding up the toothed wheel. It appears to maybe have 36 teeth, with one missing (36-1). The toothed wheel looks like it is aluminium; because of it's colour, but is probably iron. That means the sensor could be a VR sensor, or maybe a Hall sensor, with a magnet built in behind it. Have to await the next episode to find out. I gather it will be hooked up to, a Haltech ECU ? I have taken this a step further, because I what to synchronise the CAS signal, produced by the camshaft, with a crankshaft pulse, which will produce a pulse, that appears, as if it was produced by the crankshaft, that is "rock solid", timing wise. Cheers Banjo

Hi Graeme, No, I haven't ! I used to follow them religiously, in the early days, but haven't watched them, for a while now. I'll certainly go take a look in the next 24 hours. My exercise with the 24-1 punched hole S.S. disk & the Mitsubishi module; is to be able to compare the performance of both, & see if there is any perceptible bettering of performance with the high resolution 360 slot disk, with 2 degrees resolution over 720 degrees of rotation of a full engine cycle, as opposed to the 24 slot disk, with just 30 degree resolution over 720 degrees of rotation. I'm always trying to find the limits of "things electronic", in things automotive applications, as breaking down "crossing the "Hay Plains", or similar long drive, could result in a very expensive tilt truck ride. I've never had to be towed in my entire life;; so not planning on starting now. Strangely, I came across an issue this morning with my setup, that has me baffled. I had the Speeduino running on the bench with my motorized camshaft simulator. I then pulled the CAS plug input, & was surprised that the Speeduino ECU continued to run perfectly. The readings on all the guages on the Tuner Studio dashboard, still read correctly. However, when I shut down the ECU, & restarted it, the ECU would not run, until I plugged the CAS sensor back in. There is no indication in Tuner Studio, that I can see; that indicates, that there is no CAS signal being received. So in real life, I'm driving across the "Hay Plains" & unbeknown to me the CAS signal Hall Sensor falls off, or becomes defective. I have no idea this has occurred. The engine continues to run perfectly. The half way across the plains, I stop for a break & a drink, & let the engine cool a little (it's the middle of Summer !) I hop back in to continue my trip. The engine will not start ! It was running perfectly when I stopped. This seems unbelievable; as up until I stopped for the break, there was no indication that anything was amiss. I need to add a bit of circuitry, that monitors the CAS pulse presence, whilst the engine is running, & alert the driver, if the CAS signal drops out. So still not believing that this is possible, I ask Google AI the following question. Google AI did it's homework, for me, & Here is the answer it came up with. A Speeduino ECU requires a Cam Angle Sensor (CAS) or Crank Position Sensor (CPS) signal to establish its initial synchronization and properly fire an engine. However, it can continue to run after the signal is lost because it uses historical data and prediction to maintain engine timing. This is common behavior for many ECUs, not just Speeduino. Why the engine needs the CAS signal to start Establish a baseline: Before the engine can start, the ECU must determine the exact position of the crankshaft and pistons. It uses the CAS signal to find a known reference point, typically a "missing tooth" on a trigger wheel, that corresponds to the engine's top dead center (TDC). Calculate ignition and injection timing: Once the ECU knows where the engine is in its rotation, it can accurately calculate the correct moment to fire the ignition coils and fuel injectors. Without this initial reference signal, the ECU cannot establish the engine's position and will not send any ignition or fuel commands. Predictive timing: While the engine is running, the ECU receives a continuous series of CAS pulses. If this signal is suddenly lost, the ECU doesn't immediately shut down. Instead, it predicts the upcoming pulses based on the engine's most recent speed and acceleration data. "Keep it alive" mode: This predictive, or "limp-mode" function, is a built-in safety feature in many ECUs. It allows the engine to continue running for a period, though often in a degraded state, which can prevent dangerous situations like sudden stalling in traffic. Sequential vs. wasted spark timing: The type of ignition timing can also affect how the engine reacts. With a sequential setup, which requires a CAS signal for cam position, a lost CAS signal would cause a major disruption. With a wasted spark setup, which only needs crank position, the ECU has an easier time predicting timing based solely on the last known crank speed. Degraded performance: The predictive timing is not as accurate as live sensor data. While the engine may keep running, the ignition and fuel timing will likely be suboptimal, which can lead to reduced performance, rough idle, and misfires. What happens next Once the engine with the disconnected CAS sensor is shut off, it will behave exactly as it would if the sensor were disconnected from the start: it will refuse to fire because the ECU has lost its synchronized state and cannot establish a new baseline for timing. _____________________________________________________________________ Google AI, advised it visited 10 off sites to detect the answer it provided. I'll go & have a look at these sites, & see what they say. Actually the Tuner Studio website was one website I saw listed. As an aside, I asked Google AI a couple of weeks ago, a question related to what I'm working on. I assumed Google AI would not source it's info from forums, but only recognised websites. Imagine my surprise, when one of the sites it visited was RollaClub. Even more surprising, was that the piece of info it had sourced; came from a post I placed on this subject, back in 2022 ! Cheers Banjo