Ok so heres the deal! My 98 2.4 has a problem it idles at about 500RPM, the idle is rough like it has oversized cams or something, and goes up and down. also when i start it after it sits even like 10hrs and i dont let it warm up for like 15mins when i put it in first and try to drive it wants to die. I can tell that i am not getting all the performance it should be putting out. I hooked up the coder and its reading a misfire in multiple cylinders(P0300). i have changed the spark plugs because i was running Bosch plat 4's went down to NGK plat singles. tried new coils and boots as well, still nothing! any suggestions??

could be wrong... butttttt... clogged fuel filter? or bad fuel pump?

^^^^^ plugged fuel filter.... mine did the same thing. and the fuel fitler was horrible so i bought a new one and it runs fine now

first of all you need to get some actual ac delco plugs...might have a vacuum leak..map sensor issue..TPS problem..even an o2 sensor going bad..do you have any idea how many things could actually cause the problems your describing ? time to get a REAL diagnosis..and if you cant do it yourself , then i suggest time to take it to a shop....

Fuel filter sounds plausible, especially if your CEL is off. The plugs aren't going to be the problem. I'm running NGK Coppers (The V-Power ones) and they work just as well as the OE Delcos did.

I would start with trying to find out why its idleing at 500 RPM?


TPS\IAC...

Thats where I would start.


Yes, A bad TPS dose not always throw a CEL for itself.

Chris




'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08