Hello all. Im new to the board here. Ive been a long time member of clupgp.com, but cant seem to find the info i need there so i came across this great site. Anyways, ive got a 2004 Polo Green Comp G. its been a great car, but recently its developed a nasty misfire. Heres what happened.

around 70,000 miles i changed the trans filter and fluid. Then the car developed a misfire on cylinder 3. No big deal, thought it was time for new plugs and wires anyways. Went to Advance got the autolite 104's and autolite plug wires, still had the misfire after replacing those. At around 2000 rpm, whether im going 5 miles an hour or 60, the car chugs, with a lack of power. It does it when its cold and hot. Next, i checked the coil packs, everything checked out OK, but to be safe i tried a known good used set, still had the misfire. Next i changed the fuel filter, still a misfire. Next, i had the ignition control module checked. it checked out ok as well. After this i put a second new set of AC Delco plugs and Autolite plug wires on it. Finally, i did a fuel injector cut out test, passed with flying colors. through out this whole process my check engine light has never come on. I called the local Pontiac dealer, and was told that the first thing they are gonna do is put AC Delco plug wires on it. Im not buying it. I just dont believe that 3 sets of plug wires could be bad. So, right now im leaning towards a crank sensor, or cam sensor. But i would think that if one of these were bad it would def trip a code. Im at the end of my rope here...any advice or suggestions would be greatly appreciated.

I don't know what a fuel injector cutout test is, but did you move the #3 injector to another cylinder? Did you swap your coil to another spot to see if the misfire moved with it? Over the years I have had misfire issues come up and it has ALWAYS been one of the following.

Plug
Wires
Coil
Module
Injector

I have had everything on that list go bad other than the injector.

_________________
04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

The Snap On Scanner i have does a individual injector cut out..basically measures fuel pressure and injector pulse. Its misfiring on all cylinders. Some more than others.

Plugs: ive had autolites and now ac delcos
Wires: 2 sets of Autolites. Dealer suggests AC Delcos, but i dont see this being the problem
Coil: Tested my coil packs, they checked out ok. Had a set of good used ones, tried them, same misfire issues.
Module: Took the module to advance auto parts, they tested it over 25 times to get it good and hot. passed every time
Injectors: tested with a snap on scanner, then removed all injectors, cleaned and put back.

changed the fuel filter as well

Ive heard people talking about O2 sensors, catalytic convertor and crank sensors...

Is the ground that connects to the module bracket connected? It comes out of the harness right around the module and had a large metal loop connector on the end.

-- Mon Sep 06, 2010 11:51 am --

What are all of the codes you are showing?

_________________
04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

No codes. Just current misfires and misfires in history. Ill check the ground. Thanks

When I did my build the ground was missed when putting the bracket back on. Caused all sorts of problems with misfires.

_________________
04 GTT - Retired
Best ET 13.016
Best Trap 115.56 MPH

Let me say I am having a similar problem I used to get misfire codes and changed the plugs and wires. I am still having the same symptom but now I am getting a bad O2 sensor issue. Not sure which sensor, Onstar or Advanced could not say from the code. I will check with Autozone to see. Onstar said the sensor is causing Fuel connection issues due to a possible failed sensor. So we will see when I get my sensors in if that is the problem.