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Car Pinging


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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.



Edited by ms85er
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Got any error codes showing?  Can you check the injectors output into a measuring cylinder over 15seconds & see if its 50cc or over?

Is it running an oxy sensor??  The ECU should alter the mixture according to the sensor's voltage.

Is there an intake leak via a hose or somewhere, something outside the ECU's ability to compensate for? All you can do is go over it again and see if there's something you missed. Maybe something tucked away under the intake manifold.

Can you beg, borrow or steal a mixture display, wideband or narrowband, just to check what the oxy sensor is sending. Even a multimeter might do it, the oxy sensor produces 0.5volts at ideal mixture & you could tap into it's wire to read it. Maybe take it to a garage who has one to get a reading at cruise.

Chase down Parrot's 4AGE diagnostic manual and use a copy of that. If you can't d'load it I can email you a copy, its only 6meg compared to the full 4AGE manual at 90meg. A lot will be common between the engines.

I think if you can make sure the mixture is correct you will solve the pinging at the same time. 

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I actually had the outer ring on the engine damper, the rubber bonding, allow it to move more then 20*. Put a screw driver in the number 1 plug hole and turn the engine over by hand to TDC. Verify the timing mark aligns with the notch on the outer damper ring.  If the timing is correct and the injectors flow and pattern looks good. Double check again for vacuum leaks.  Davew7

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