sowaidi

iTrader: (5)

Hi
​​​​​​Appreciate all useful input.
I got a mail order pcm from Wait4Me. After installing it, I get a P0300 Random Misfire code. I checked all connections, cleared it but it cpmes on again.
The engine light shuts off and doesnt come on with the stock pcm. It did not have any codes before also.
I talked to Jesse at W4M, he says that his pcms are more sensitive to changes and will uncover more problems than a stock pcm. He insists the pcm and the tune is fine but Im bugged because the stock pcm throws no codes and i dont feel any hesitation being also a 5 speed whichd be easier to feel.

Truck is bone stock
2000 GMC SIERRA 4.8 5 SPD 4WD- 137K
New fuel pump and filters

Atomic

iTrader: (42)

Typically that code is from a cracked spark plug or burned/shorting plug wire.

Wolftrk99

iTrader: (5)

It could also be caused by truly random multiple misfires... if its a different pcm or os could that set the code, especially if the original pcm isnt throwing it.. or something in the tune being much more sensitive to misfires somehow? Are you performing a crank relearn with the new pcm?

sowaidi

iTrader: (5)

the spark plugs and wires are new, it did it vefore and after them.

i havent performed a crank relearn.

Wolftrk99

iTrader: (5)

May want to try that, if the crank relearn isnt done it could see a variance as a misfire. Am i reading correct that you have a different pcm than your stock one?

sowaidi

iTrader: (5)

yes sir. i have a different pcm that i got from wait4me. havent had similar issues in the past with mail order tunes from him. My stock pcm is fine and i didnt have the codes previously. as soon as the truck is running after the w4m tuned pcm, the light turns on and when im driving sometimes blinks on and off. as i said, no codes with the stock pcm, i put it back.

Wolftrk99

iTrader: (5)

Thats sounds like an issue either with the tune in that pcm or an issue with tge pcm itself