ms85er

ok ill give those a try, thanks

Hi, I have a 5mge toyota cressida engine (rebuilt 2 years ago) and I have issues with the car running learn/pinging. I pulled the spark plugs out and the grounding strap was WHITE AF, lean and overheated. I have since put in 1 colder plugs, but it hasn't done much. The spark plugs are consistent across all 6 cylinders, all white and overheated. This problem is an absolute nightmare, because I have chased every possible thing that could cause it, well, almost. Fortunately I have a tonne of spares, and this efi motor is quiet old so it's very simple. I'm fairly sure its the same bosch ignition system as the early bigport 4ages. The only unique things about the car is that with a combination of ma61 and ma70 supra parts I converted it to manual. So the auto ecu is very confused and has a lot of codes but does not effect that driving of the car (I assume it wouldn't effect fuel mixture) and it has a pod filter on it (apparently some motors can randomly get upset by different intakes). Things I've done 110% check fuel system up until the fuel rail. Replaced fuel pump (even though there was nothing wrong with it), the tank is clean and full of 98. Checked fuel pump wiring, fuel pump itself is running through a 12v regulator because the alternator in the car is a bit average. Filter is fine, I replaced that. AFM replaced, O2 sensor replaced, Throttle Position Sensor replaced and tested working with TSM. ECU replaced (I have 3, no differences). Knock sensor replaced. Wiring checked for continuity between major sensors and ECU, all good. No vac leaks that I can see. The car does not hesitate at all, but when you put the gearbox in a high gear like 4th and cruise under load you can audibly hear it pinging. It gets quiet bad. Timing has been check MANY, MANY times. I even retard the timing just so I can drive it without killing it. I'm at my wits end, the only thing I can think of now is the fuel rail and injectors. The injector o-rings were brand new when I put them in 2 years ago. Is it possible for injectors to have a bad fuel spray at certain rpm, and is it possible that a clogged fuel rail could cause this? The car runs great, no hesitation at all, it just pings at certain rpm and I don't want to kill the engine over time. Also, I've looked in the coolant and oil, no BHG, and no visible signs of any cracks in the head. However, I'm not that sure about symptoms of a cracked head tbh, but I'm faily sure it's ok. Thanks all.

Ok thank you both for your responses.

Could I kindly get a yes or no response please. Can u put different gears in a gearbox or is it too expensive?

Hi thanks for the response. It's a heavy car And I already have the best diff gears for highway cruising. A torquey first and second is suitable. I need a better fifth however

Hi, Is it possible to frankenstein my W56 gearbox and the fifth gear from a W58 in it. Also, how expensive would it be for a transmission shop to do it. Cheers.

I was really hoping to avoid spending money, but thanks for recommending master cylinder exchange at wynnum. I got the master cylinder and proportioning valve rebuilt there. It was in much worse condition than I first thought, the piston was seized. He took a look at the proportioning valve as well, and machined a new part for it, it was all very reasonably priced as well. I guess it does pay to spend the money to get it repaired right otherwise it probably would of just spread rust to the rest of the system and seize up brake pistons as well. She's looking good now

Awesome car, a lot of work ahead!

Hi all, I've had to source a brake master cylinder and proportioning valve from the wreckers for my car. The parts are in reasonable condition with a bit of rust on the outside housing, the guy at the wreckers said the car had been sitting for at least a few years. I looked up some parts catalogs and it appears they don't make rebuild kits for it anymore because 1981 was a while ago (its not a corolla). Basically I want to throw these parts on the car but I don't want them seizing up all my brakes. I read you can soak the master cylinder in vinegar, and put it in the dishwasher apparently, don't think the misses is gonna let me do that. If I have some rust inside the piston area is this a reasonable idea to soak it in vinegar for a bit and throw it on the car, or is there any other way I can cheaply and easily do a minor reco. I wouldn't trust myself completely pulling one apart and putting it back together correctly haha. Cheers

Too right. Experience helps a lot as well. Your electronics engineer mate sounds like a handy consultant.

Yah my post probably seems confusing because the whole thing was confusing. It was at the point where I was trying anything to get it to work. Those multi-meter readings were wack. An interesting thing I learnt was that the alternator really does push out most of the voltage to operate the vehicle. If for some reason your not making close the 13.8 or 14.2 area at idle your 12v battery doesn't do a whole lot. It will keep the car running but they are optimised for starting the car primarily. My problem was varying voltage making lights go dim and fuel pump struggle. I had this issue with the first alternator and the second reconditioned denso alternator (thats right a faulty reconditioned denso). The denso alternator also threw the charge light but my old alternator didn't. I didn't think adjusting the idle and throttle cable was really necessary as the car idled fine. However, while it did idle in line with typical idle for that engine, its recovery from an idle drop was just too slow. This is where that idle adjustment thing also helped, so the 14.2 volts would go down below 11 volts. As I learned the battery is really only for starting the car, it just can't handle the demands of fuel pump and lights that well. It's funny because only 1 website out of 12 I visited actually explained that correctly. Every website that thoroughly explained charging systems basically gave the impression that if the alternator isn't working it just won't charge the battery.

ITS FIXED!!!!!!!!!!!!!!!! So I have no idea what those erratic multi-meter readings were all about, maybe my multi meter is stuffed, Also, I purchased a reconditioned 100amp alternator which was fitted to the car when I was having these issues and it was faulty. The problem was a combination between throttle cable and idle adjustment, although the particular motor I have doesn't technically have an idle adjustment, it's an "idle bandwidth" type adjustment for the ecu, its primarily used to adjust the idle. So overall it was a massive headache. Thanks for the help everyone!

So update, I have tested everything imaginable. I get 14.2 volts at the battery at idle, however its not consistent. As soon as the idle drops the voltage goes all over the place down to 11 volts or even lower. Installed a brand new battery today. No difference. The Fuel pump was certainly not getting enough power, the ignition system is barely getting enough power at low rpm, car randomly stalls. I have put a voltage regulator on the fuel pump and it works brilliantly now, I can hear it loud and consistent now. So I was using the alternator that came with the motor when I had these issues. I installed an denso reconditioned 100 amp alternator with appropriate pulley. The pulley ratio is still very close to the original pulley that came on the alternator so that's got nothing to do with it. The only difference is since the first aged 70amp alternator and the 100 amp I now get a dim alternator light on the dash, where as the 70 amp alternator was happy. I have run a wire directly from the post on the alternator to the positive on the battery with nothing else hooked up, makes no difference. I've installed extra grounding wires and check the voltage at the post of the alternator to the battery ground and there is the same 14.2 volts at idle. The sense wire going to the alternator reads about 14.1 volts but I don't see there being any issues there as the alternator just needs to know roughly what voltage the battery is at. Anyone here an auto electrician, I give up.

I'll try and get a reading with the DMM when I can get someone to help me, can't drive and get readings myself.

Thanks for all the suggestions. I've thrown a 100amp MR2 alternator on it already :P So I noticed something interesting when I drove one of my other cars today. It does it as well! just not as bad. So apparently the current draw of the fuel pump just cannot be sustained at low rpm. When I reverse into a car spot I can hear the frequency of the pump drop as well. So basically the only solution is to probably bump up the idle a bit. It strange though because I would of thought if the alternator drops its output below 13.8v that the 12v battery would take the hit and act kinda like a capacitor to keep the voltage up to the fuel pump since it can handle large current draw from the starter I would of thought the small amount drawn from the fuel pump would be no problems, apparently not. So long story, me being paranoid about killing the fuel pump is just me being paranoid. The lights do dip a bit but they aren't so much of a problem. It would appear some fuel pumps don't get the required juice at low rpm is my conclusion. Think I might buy a voltage regulator to throw on the fuel pump to maintain longevity so I don't have to pull my fuel tank apart again. https://www.powerstream.com/dc2.htm looking at the PST SR500 13.8v output with 15 amps continuous supply. I saw a guy on a supra forum threw one on his fuel pump to maintain a solid power supply for his 2jz supra making big power.