LT4 check engine light blues
Thread Starter
Advanced
Joined: Sep 2003
Posts: 53
Likes: 1
From: hamilton square nj
i can't see down by the distributer too well, all i see is a blue light coming from the front of the engine, by the coil, and where the plugs are. at the plugs i don't see arcing, and at the coil it doesn't appear to be arcing just a blue glow. but i can't tell by the distributer. the engine seems to be running pretty well. i would imagine if i had all that crossfiring i would feel it. as far as running too rich or lean, all the plugs are burning identically, and all well. i have'nt done a leak down test yet, just compression, and they were all about the same, no one cylinder stuck out. it doesn't look rich, or lean, or lacking in compression. if the new wires don't cure it then i will do a leakdown test and go through it one wire at a time.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Really don't think you have an ignition or a compression problem (unless there's a burnt valve). Looking at your mods, you've added addt'l air and the means to get it out, but done nothing for fuel. That makes conditions ripe for a lean mixture which leads to high combustion temps and if there's any restrictions to fuel flow, a lean miss. You may not feel it, but you did say there was a loping idle. The computer isn't looking for what you can feel anyway - just poor emissions. If the situation didn't exist before the mods, then suspect something about the modifications you've made (especially if they didn't exist before you made them) along with something else and if the ignition checks out, it's probably fuel related, or maybe a vacuum or header leak.
Burning Brakes
Joined: Aug 2001
Posts: 797
Likes: 2
From: Westminster MD
Originally Posted by pettsir
here is something funny, i replaced the PCM twice, the first replacement PCM caused the car to stall after 20-60 minutes of driving and set about a dozen codes or so including PCM memory codes, ignition high and low resolution faults, random misfire, MAF codes, skip shift solenoid code, etc,etc. so i exchanged that one for another from where i bought it from, and i even had a Chevy dealership flash it for me. the car no longer stalls, runs great infact but still sets a P0300, and that's when it isn't setting a P0303!!!!!
