Weak Spark Help?

[ATOYOTA]

I know it's not a corolla but I'm hoping someone can be of help.

 

I'm having a major problem with starting my charade and I've traced it back to a weak spark coming from the coil.

 

Just cranks over and doesn't attempt to spark and when I pull a lead out it has a very weak spark. Tried cranking with the coil lead earthed and again, very weak. Plugs are white as the KKK.

 

Checked fuses and they're fine.

 

It's had trouble starting before where it's taken a few cranks and struggling to start.

 

I was wiring up a tachometer and fiddling around with wires under the dash. Started the engine fine, then turned off for about 3 seconds, then would just crank with no attempt to fire.

 

I also tried with a known working coil/igniter and still no dice.

 

That's about all I can think of that's happened. Can anyone shed some light? I've looked all over google & forums and can't find a solution.

[Clapped out]

Where you have played with the coil, most cars have a 12v boost to the positive side of the coil when cranking, possibly could have been accidently disconnected?

 

cheers!

[tojo2]

don't know how charades are conected but yea measure voltage on coil primary while cranking

[ATOYOTA]

Charades have a single coil pack. Might have to unplug and use wires.

 

I'll try it out this morning and keep you posted.

[ATOYOTA]

I just ran a couple of tests on the coil.

 

The 2 input terminals on the coil read 2.6 ohms when disconnected and the wires are ~10V when standing & ~8V when cranking.

 

What's the lowest voltage a coil can spark on? 8V seems a bit low.

[altezzaclub]

What's the lowest voltage a coil can spark on? 8V seems a bit low.

 

that's why the KEs run an 8V coil with the ballast resistor. They work at 100% efficiency when cranking, then the resistor drops the usual 12V to 8V when running.

 

However if the Charade doesn't have a resistor then its designed to start at 8V. There only needs to be one wire on the coil +ve in that case, it should supply full voltage when cranking and when running, but obviously 'full' voltage is only 8V when starting. The other factor would be a poor battery that coulsn't crank and supply the coil with enough voltage.

 

I also tried with a known working coil/igniter and still no dice.

That's a worry, so we can assume the coil is fine. Is there anything else involved, or just a coil and a transistorised ignition pack inside the dizzy both of which you swapped at once for no result?

 

How about you feed the coil +ve from another battery using jump leads and see what it does. That will guarantee 12V to the coil.

 

If that fixes it then start hunting for some wire in the circuit that is robbing current from the coil +ve, or a bad earth on the coil -ve side.

 

There are stacks of Charade wiring diagrams on the web, the one I looked up had a ballast resistor, so can you post a link to the diagram that refers to your model?

[dannyl]

low spark, low cranking voltage on your primary circuit. did you burn a circuit in your ignition switch? hnnn.

when cranking..different wires are in use than when the key springs back to the run position, when you let go.

 

determine which is which then volt check the cranking primary. that circuit's brass may be dirty or cooked the grease inside the switch. a "white eraser" for erasing ink on paper works great for cleanup. that is , if you can safely and carefully get it apart without losing the springs. use a clear plastic bag, disassemble within the plastic so they don't get away.

 

often, the "testing ignition switch" description in the written part of the service manual will give values for pass/fail for each circuit, and when, in what position. reassemble using silicone dielectric on the contacts.

 

search the wire in question to where it got boogered so it doesn't reccur. The value of the resistance including the ballast should be a spec you can look-up. if its too high then you have found the bottleneck for the cranking voltage...ya falla?

 

hope this helps.

[ATOYOTA]

I wired up a relay to the coil +ve which jumped the standing voltage to 12V but cranking still sits at 8V. The battery's also brand new, only a month or so old and it produces 12V. Maybe it's something on the -ve terminal side of things?

 

Here's a pic of the ignition module:

Yellow/green wires go to the relay.

 

Can you put up a couple of the links you've found? I've looked for diagrams but they all seem to either not exist or the websites are dodgy. It's a 1996 G200 with the 1.3L HC engine.

 

EDIT: I'll try testing the back of the barrel to see if it's broken at all.

Edited April 29, 2014 by ATOYOTA

[dannyl]

i keep re reading you have verified a voltage drop. a condition where the conductor or its connections have excessive resistance. poorly conducted volts get used and become heat as the friction has increased. when an amp travels, its pushed, by available electrical pressure (or volts) if theres resistance things begin to cook, if some, but not much, it uses the voltage up. thats how your reading drops to 8 if you are looking for 12.

if the resistor is supposed to be there, like a ballast resistor, it will be placed where theres passing air to cool it. if its in a circuit board or (dizzy?) it will have a heat sink.

this is why i suspect during the tach installation the cause of a burned circuit may have occurred. its anybodys guess what happened. but the ignition switch tests will take it (the ign. sw.) (barrel?) off the list. ohm readings of the harness wires in question will isolate them to separate them from the list of causes. each wire , disconnected at both ends, should read less than 1/2 ohm or .5 ohm. each connection should read the same. am i being too simple? if two wires are burned together enough to touch, there will be continuity between them and so the same is for continuity to ground (shorted) am i violating the prime directive?

Edited April 30, 2014 by dannyl

[altezzaclub]

am i violating the prime directive?

 

being "Do not let the smoke out of the wire!" Wires conduct electricity as smoke, and if the smoke escapes nothing will work...

 

ATOYOTA the diagrams I found again were for models other than the G200, most being the G100 series and others older. You seem to have an unusual one there when it comes to the web.

[ATOYOTA]

You call it a switch, I'm a locksmith so I refer to it in the closest thing I can relate to: the ignition barrel. It's all the same assembly, one love mun . I think you might be right in that it's possible I've blown something in my carelessness (it's a charade, alright? It's not like I could give a fvck about it unless it quits) and sprung a smoke line.

 

___________________________________________________________________________ |

___________________________________________________________________________ v

When I get a chance to see it in some light I'll hook up my smoke detector to the ignition --->SWITCH<--- and see if any smoke's escaped.

___________________________________________________________________________ ^

___________________________________________________________________________ |

 

Let's just hope it's nothing major that's expensive and/or hard to find. I feel like every dollar I'm spending on this thing is another delicious creme egg I won't be having from the servo next fill up. AND I REALLY LIKE CREME ʞ©$ɟING EGGS

[Taz_Rx]

...... Maybe it's something on the -ve terminal side of things?

 

You say this started after you wired up a tacho.... Are you sure you haven't accidentally earthed the write to the tacho somehow? As that could sap all of the power out of the coil!

[Hiro Protagonist]

being "Do not let the smoke out of the wire!" Wires conduct electricity as smoke, and if the smoke escapes nothing will work...

 

[ATOYOTA]

Thank god I don't drive an old jag.

 

You say this started after you wired up a tacho.... Are you sure you haven't accidentally earthed the write to the tacho somehow? As that could sap all of the power out of the coil!

 

The tach is wired to the negative lead on the coil, and I disconnected it from the coil when testing. As Dan suggested, the most likely explanation is that I've shorted a wire while carelessly poking & prodding plugs behind the dash.

 

I've gotta pull the whole dash apart to see where the coil wires lead to but I'm waiting til it stops raining first because the car is parked outside up a hill from the carport, and I'm a big girl and don't wanna get wet.

[dannyl]

still thinkin, its a manual trans right, so the wires for primary and start are going to the ign. sw. but theres gotta be an ign. fuse either in the fuse panel or inline. cruddy connections or one thats had numerous short burns could cause it. so... was there smoke getting set free? volt meter used throughout at each connection should show where it drops. ohmmeter used with batt cable off can show the resistance. if you feel like you need a crash helmet, draw the circuit as you see it while you are finding it. thats what i had to do for my ke20 because the map i was able to get was so different. and if you have electronics mucking up the search,

theres nothing like comparing it to one that works.

 

i had to delete my seat belt interlock on my old ke20 for mucking up the circuits. and the emission box on the passenger side had a circuit, but these are about cranking i think. wiring was really a mess in the 70's

 

i once had a turnsignal wire that rubbed on a stereo screw under the carpet. a few broken strands of copper made the flasher squeal and moan leading up to each blink. the screw was diverting some of the juice. she was a happy camper in those days.

now, theres dropping 12 to 8

Edited May 4, 2014 by dannyl