Engine Misfire Issue, HELP!

**worshipmekaythnx** · 06-19-2012

Hey Guys!

Ive got myself a 3.8SC grand prix, since I bought the car it has randomly thrown quite a few codes but the usually go off within the hour. The other day, I got a check engine light which read cyl4 misfire. Now, i have already replaced all the plugs and wires, they dont have any burns and the plugs are ok, i tested the coil packs using an inline spark checker, they all were good. Question is where do i go from here?

The weirdest part of it is that the car still picks up great drives awesome, just on idle it is rough and skips.
any input would be appreciated

**Fivefingerdeathpunch** · 06-19-2012

What brand plugs?

Have you switch the coil packs around yet?

Maybe it will transfer to another cylinder.

It could also be a ICM problem.

**worshipmekaythnx** · 06-19-2012

I'm using ac delco plugs.. I haven't tried switching the coils yet, but I will.
& as for the icm, that confuses me.. If it was the icm wouldn't I be getting misfires all over or no?

**Fivefingerdeathpunch** · 06-19-2012

ICM's like to be difficult.

They can test good, but still be bad, they can cause problems at random.

Try swaping the coils around first and go from there.

**worshipmekaythnx** · 06-19-2012

Alright, will do.
Also I'm having an issue with my ac compressor.. I'm about to take the dang thing out! It won't engage. I have been having an issue with my cooling fans on constant as someone hot wired them that way before me. I finally got them fixed to come on and off but now my compressor isn't pushing out, it's bad anyways so it sounds awful and it's insanely loud, any suggestions?

**dsmuts** · 06-19-2012

Just swap out the compressor?

**worshipmekaythnx** · 06-20-2012

Well yeah, but it's not engaging at all.. It was before I situated the fans. Something to do with the wiring I assume? It needs to be swapped out, but before I buy a new one, I wanna make sure it'll actually work

**BillBoost37** · 06-20-2012

Please share the host of codes you were getting. It's quite possible your issue may lie in there.

**dsmuts** · 06-20-2012

Run all the ac lines and make sure all the clips are pushed down tight. I just "fixed" someones ac by replugging in the one of the pressure sensors on a girls car.

**FordMan77** · 06-20-2012

It could also be low on freon to the point where the compressor won't engage the clutch.

**dbextreme** · 06-20-2012

You can also pull the number 4 plug out. Once it's out stick it back in the plug wire, hold the wire at the base of the boot closest to the wire NOT the plug, ground the plug threads on a piece of metal (like the bracet on the back of the motor with the round cutout in it sticking straight up that's used to hoist the motor out) then have someone start the car. If the plug is firing fine you should get a nice bright white/bluish spark. If it's any other type of spark then you are not getting proper fire to it. I would say coil pack if that was the case because you know the ICM is sending signal to the pack itself.

Moving coil packs around just isn't as much fun as my way!!! LOL

My 2 cents.

**Scottydoggs** · 06-20-2012

Originally Posted by dbextreme

You can also pull the number 4 plug out. Once it's out stick it back in the plug wire, hold the wire at the base of the boot closest to the wire NOT the plug, ground the plug threads on a piece of metal (like the bracet on the back of the motor with the round cutout in it sticking straight up that's used to hoist the motor out) then have someone start the car. If the plug is firing fine you should get a nice bright white/bluish spark. If it's any other type of spark then you are not getting proper fire to it. I would say coil pack if that was the case because you know the ICM is sending signal to the pack itself.

Moving coil packs around just isn't as much fun as my way!!! LOL

My 2 cents.

you never want anything except for a blue spark, no yellow, no white, no orange,"BLUE!"

**worshipmekaythnx** · 06-21-2012

ok, so i swapped the coils with no change, changed the plugs and inspected the wires, all good there, seemed to be ok at first but then went right back to its ways. I brought it to have the codes read and i have 3..
P0141- o2 sensor heater circuit bank 1 sensor
P0300- engine misfire detected
P0480- coolant fan 1 control circuit

im starting to assume the o2 is causing my problem.. but any thoughts would be great!!

**Rico** · 06-21-2012

Originally Posted by worshipmekaythnx

ok, so i swapped the coils with no change, changed the plugs and inspected the wires, all good there, seemed to be ok at first but then went right back to its ways. I brought it to have the codes read and i have 3..
P0141- o2 sensor heater circuit bank 1 sensor
P0300- engine misfire detected
P0480- coolant fan 1 control circuit

im starting to assume the o2 is causing my problem.. but any thoughts would be great!!

O2 code might just be a symptom of the engine shutting down abruptly.
A real-time scan when it is acting up would tell you a lot.

**BillBoost37** · 06-21-2012

It's showing a heat circuit issue..not a fueling issue. That just means the heater in the O2 to bring it up to temp and read better quicker isn't up to par.

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