I would like to know every engine sensor that would cause a part throttle stumble or cause the PCM to pull timing, at WOT the car runs fine. I have OBDII and no codes. The reason I ask is I have alot of knock retard happening here all the time except at WOT, it seems very correlated with the stumbling. I even have EXACT SAME knock retard numbers after I disconnected the knock sensor, then replaced it with a resistor, then ordered a NEW knock sensor and left it outside the block, wtf? Seems like the PCM doesn't care about the knock sensor, it's either internally f'd up or using some other sensors to pull timing. I even REPLACED the pcm, acts the same way, I'm

Here's what I've replaced:
-opti
-plugs
-wires
-ICM
-PCV valve
-coil
-02 sensors
-new PCM
-blocked off EGR system
-new PCM with knock sensor programmed out

Here is what I've checked:
-fuel pressure OK
-vaccum check at idle OK
-disconnected MAF ran car in speed density, same thing stumbles


I have a scanner I am not a PCM expert would like to know what to look for.

Thanks
Brian

 

anyone?

 

Can't help, but I'll give ya the bump.

 

The throttle position sensor (TPS) is a possibility, but I’m not sure. There is an OBDII DTC for TPS voltage error, but anything is possible (TPS bad, but no DTC). The TPS is basically a variable resistor (potentiometer) and can have a worn area. That could explain why WOT is OK, but problems in other throttle positions. It isn’t too expensive either, so good luck.

 

what is the knock sensor reading showing on the scanner? WOT and P/T. If you're picking up knock readings, I would check the knock sensor circuit directly at the PCM connector. Use a voltmeter, set to the 20V DC scale and probe the wire. I think it is dark blue, could be wrong. See if the voltage is swinging. It shouldnt move if you have a resistor stuck in it with no knock sensor. Or just unplug the sensor and the voltage should be stuck at 5V. With sensor plugged in and NO knock, readings should be around 2.5V. Ignition on, engine off, sensor connected, 2.5V. Oh and leave the PCM connected during the whole process.

 

I checked the TPS on a scanner, looks good.

ALso, when the car is cold and not warmed up, the PCM will not pull ANY TIMING. As soon as the car warms up, the PCM goes mad and pulls timing like a **** and the car gets the part throttle stumbling problem.

I tried everything to disable the knock sensor, I even had it programmed out in the PCM and it still pulls timing! I've had it replaced with a resistor, I had it disconnected, and i bought a new knock sensor and hooked it up and left it outside the block so it can't possible detect any knock. All this doesn't make a difference, the PCM still pulls timing the same way all the time. I contacted the tuner about it he didn't get back to me as of yet, but I'm confused. It's almost like the PCM is using other methods to determine knock retard, like combination of other sensors. ANd yes, I even tried a new PCM still the same deal.

All i know is, it's isolated to this:

part throttle stumble that occurs when large amounts of timing is pulled, which only happens after the car is warmed up. When the scanmaster shows 0 timing pulled, the car runs perfect. And when the car is stumbling, if i just give it WOT the PCM will then pull 0 timing and the car will take off like a raped ape.

Anything else come to mind? These all look good on the scanner but I might have to just buy these ALL, this sucks. IAT, TPS, and MAP....

 

dont throw money at it just yet. What does the voltage read at the knock sensor wire???? directly at the PCM.