Multi misfire

[snowcolt17]

Sup guys long time since I been here. Did t wanna register on another forum just for this one thread.

Btw I got rid of the foxbody,traded it for a 96 1500. Sold it and got me a 02 accord. Gas sava!

Anyways back on track..
Not a fbody but still a 3.8.. I know so e of you are 3.8 gurus so here it goes

My brother has a 05 Grand Prix. 3.8.
He was going down the road and it started acting up. Pulls over and smells sulfur. Pops the good and the cat is glowing red. Take a saw up there and cut the cat off gut it and test drive it. Same thing, still missing really bad.

After a month of it sitting at a store he finially get it to his house.
Drive it for 5 miles and it uses a half a tank of gas. He said he can smell lots of fuel. Get advance to check the code and it's a multi misfire.

He thinks it's the icm. But it seems like to me it's something else. Maybe bad coils, plugs?

Anyone have any idea?

[xpbr2000]

I don't believe if its dumping fuel like that that it is the ignition. I believe you should be looking at the O2 sensors. they are what tells the PCM how much fuel to dump. thats a lot of fuel to be dumping. Beyond that I would look at the injectors dumping a bunch of fuel. both of these can cause misfires.

Moving to GM section

[snowcolt17]

Thanks for moving it. Didn't really know where to post it.

That's what I told him. I am sure it's a o2 because the fact the cat was glowing red.

[xpbr2000]

well the cat glowing red is likely do to a clogged cat but running rich can clog a cat pretty good.

[snowcolt17]

Yea. O2 being bad, causing it to run super rich clogging the cat.

I just don't see it being the icm.

Same for said injector.

Anyway to test to see if either of these are bad?

[xpbr2000]

you can scan for the o2 values and know if the O2 is performing but if its a leaky injector the o2 may be trying to compensate so i dont know how accurate that will be.

I don't believe there is an easy way to test an injector.