strange miss...whats going on???

[newtypedsm]

i noticed the car started running funny a few days ago. but recently it has gotten worse. i thought i had a fouled plug, but all the plugs were fine. maybe a wire? swapped out wires, and it still runs the same. i checked the ignition coil pack and it's firing to all cylinders. every injector is working, and my datalogger reads 10-12 on timing at 900 rpms. i thought maybe my GM MAF went bad, but wouldnt that cause the CEL to come on?

as soon as i start it, it idles rough, it sputters. at low acceleration, it stutters even worse, like its choking out, yet i see no smoke of any kind from the exhaust, smell no fuel, nothing. under heavy acceleration (under boost) it does just fine until 5500+ rpms, then it just backfires alot.

i have no idea what is going on, i checked everything i thought could cause a miss or stutter: wires, plugs, ignition, vacuum lines...and the problem seems like its getting worse

 

[zrk666]

sounds like it is in the fuel or the intake side. make sure the FF isnt cloged, phyisically makes sure the injectors are giving the engine fuel, fuel pump and etc but you probably already no all that. the maft and the gm maf could be giving false reading. check the sensors that are the easisest to get to like cam angle, tps, and etc.

 

[spyderturbo007]

This might sound weird, but I'll shoot it out there anyway. I had the same problem at the beginning of last year. It seemed like a slight hesitation, or stumbling of sorts. After replacing the O2, having the intake cleaned, verifying all the sensors were functioning, fuel filter, fuel system treatment, etc. I stumbled across an article on the internet. It turns out that our motors have a habit of collecting condensation in the wells of the spark plugs. Apparently when the condensation builds up, it is enough for the spark to "jump" and not reach the plug. I ended up removing my plug wires, blowing in some compressed air and letting the car sit with the hood up outside on a nice warm day. I could never figure out how it happened, as I hadn't taken off my plug wires in a year or so . Oh well, it was a free fix and something you can try that will just take a little time.