misfiring in WOT and cruise

[Kevin T.]

I have a 2000 Camaro with the M5 tranny and whenever I am just cruising and take the RPMs close or past 3000 RPM, it starts to jolt badly. I hear a slight knocking sound like a missfire. My SES light is not on and it hardly ever does this if I shift at 2500-2800. My plugs were just changed, and my PCM im told is on the fritz because I used the motor cleaner stuff at the car wash and got some in the PCM. My mechanic cleaned out the PCM the best he could and had to get it reprogrammed at the chevy place and said it was driveable. If anyone has had a similar problem and has any ideas be sure to let me know.

Thanks

[Ian]

i had the same thing. it was a coil. basically, to have the SES light actually go off, i beat on the car for about 2 minutes. it went off, started flashing, so i got it scanned and bingo, it was fine.

[BLLDOGG]

Lessoned learned. I've never believed in using anything like that for washing the engine. by hand is the only forsure way to do it.

[Kevin T.]

I know not to use the motor cleaner stuff, but could the PCM going bad actually make the car have these symptoms? It could be a variety of things, like plugs, wires, the clutch, or the coil packs. I can't really get it scanned because there is no SES light. If it was something like a coil pack, would'nt the SES light be on?

[Speed Freak]

A cloged cat will cause a misfire under load.
My car would buck lightely above 60mph
and would cause a blinking ses light under load,
but it never got a bad reading from the o2 sensor.
When it got so bad that the ses lite stayed on ,the code was for random misfires caused by the back preashure.

[Ian]

like i said, when my coil started to go and i was gettin a miss, i could feel it, but the SES didnt go on. to get the ses light to go on, i had to beat on teh car for like 2 minutes to really let the pcm see that there was a miss.

[Cole Angrimson]

mine did that and i had an injector and all my plugs replaced. the #4 cylinder was misfiring mike mad so i check the injector. it was clogged completely and then i checked the plugs. i changed them and the car has ran GREAT ever since.