This one has me baffled.
Any suggestions welcome.
The car will start to pink on a slight incline, at 15% throttle, 1800 RPM, IAT 35°C for example.
I acn't be too sure about the ingition advance as I have no reliabale way to measure it.
This car is one of those with a 5 pin OBD connector so it's difficult to get it to communicate withany decent scan tool.
I did get it to connect to an Autel but the be honest the data logging feature doesn't have very good resolution so it's a bit difficult to post process the logged data.
fitted official NGK lambda sensor.
done a fuel pressure test. - perfect
did an injector balance test - all identical
ran a can of Moly injector cleaner through the system
checked the function of the air bypas system
done a bore scope cylinder inspection
fitted new plugs / leads just as routine service
fitted new exhaust
measured TPS voltages 0.4 -> 4.59 (I guess 0.4V is okay ? but my next task is to recalibrate this to begin at 0.5V)
checked MAP sensor voltage output with reference pressure - spot on
checked IAT termistor output with reference temperature - spot on
checked vacuum hoses for leaks with Mityvac - spot on
checked valve clearances
replaced knock sensor
measured crank position sensor out and tdc sensor output - look fine
taken a feed directly from the coil primary and logged it in my Picoscope, checking phase shift with respect to tdc sensor
I did wonder if the car has had its head skimmed before I bought it. (It has had this problem from day one about 8 years ago !!!)
However, I would guess giving it more gas would make the problem worse if it was a too high compression issue.
I've probably done a few more tests but can't remember right now.
I've used both standard and ultimate fuels but with no improvement.
I think it is worse on hotter days. (Somedays the IAT sensor is about 60°C !!!!)
I even replaced the IAt with a potentiometer so I can dial in any IAT I like, but I still can't dial out the pinking.
Likewise I created a resistor arrangemt to let me mimic the MAP sensor, so to fool the ECU to read any value I want.
All I have on my list left to try is to put a thermcouple into the plenum to measure the actual air temperatue independently.
Also to measure the compression ratio, but I think I am clutching at straws.
I even tried putting the cam beather pipe into a catch tank instead of back into the plenum.
I hope I have been an idiot and missed something really simple?
Any ideas ???
Here is another thread I found, but which didn't help me, as no conclusion was arrived at.
It could almost have been written by me, it is so similar.
PS I should have said, the lambda voltage are fluctuating as normal, and the STFT is between fluctuating between about 0% and -7%
The LTFT is fixed at 0% and has never ever changed from 0% no matter what I do. Maybe it should be called a VERRRYLTFT :-)
Edited by HONDALEO, 03 July 2019 - 08:53 AM.