I have a 1998 Buick Regal GS with the 3800 Supercharged motor throwing a code P0303. I have replaced the spark plug and wires, took injector from cylinder 1 and put it cylinder3 place, Also I switched the coils same code comes up. There were some chaffed wires on injector #3 - so I taped them up as to not short them out. I checked the spark on #3 and there is spark, I did not check the compression with a compression gage but it seems to have good compression when I pulled the plug and turned the motor over.

There seams to be noise coming from the blower as well. This noise just started yesterday.When I pulled the belt on the blower the noise stopped. That was not a surprised. I would not think that the miss fire has anything to do with the the blower problem. Any sugestions on why number 3 cylinder is misfiring and keeps throwing a code P0303. BTW, the SES light is now own. A while back I cleared the codes and the code and the SES stayed off for a while. When I clear the code, only to come back when the motor is started.

Thanks for any suggestions

Some times a bad ICM will give you a misfire on one cylinder.

As for the SC noise, is it kind of a rattle? If so, it is likely a bad coupler. Take the belt off and turn the pulley back and forth. If you feel play, then you have found the problem.

Ok I'll check both. Do you know what an ICM runs new (or refurbished) or is it safe to purchase one from a junk yard? Where is the ICM located?

Thanks a bunch!

BTW, do you have to flash the ICM? Does a dealer have to???

I don't recall the price off hand.

No need to flash the ICM, it'* just the ignition control module. That'* the plate the coils are sitting on. Start by pulling off the coil that has the misfire and make sure the terminals are clean.

Dh is on his way to get an ICM this morning. Is there a way to find what vehicles and or years may interchange?

PS DanThurs - we also have a F150 too!

I do believe all the 3800 series2 engines share the same ICM

Thanks! He'* on the road now. Crossing my fingers this works. I'll keep you posted.

Good luck.

Ok, bad news...we'll good news I guess. Dh just called and the ICM tested good. So, back to square one still with the P0303 code and the noise from around the blower. This code is driving us crazy since we can't seem to pin point the problem and don't know what to do next.