New Grand Prix owner with a few questions and problems

**newmans1985** · 10-28-2014

I have recently bought a 2006 Grand Prix GT model and I have a few questions or problems with the car.

I was wondering is there a way to tell if the car has OnStar factory installed? I know there needs to be a special mirror in the car but I suspect that the previous owner took the mirror out.

The problem I am having with my car is when I start it cold it surges from 1500-1700 rpm for about 30 seconds and then it stops but when I drive it down the it wants to surge a little bit. It's kind of like it has a miss to it. I've replace the coil packs, spark plugs, plug wires and mass air flow sensor but non of it has stopped the problem. I really don't want to take it to a dealership because I feel like that is a last resort. Any help will be appreciated.

**Below Average Joe** · 10-28-2014

Take your TB off and clean it if you haven't already. Carbon build-up likes to hide behind the butterfly and make it stick and cause issues. Go to the JY and grab the ICM from another Grand Prix or Regal or anything with a 3800 really. The ICM is the silver piece that the coils connect to. Do those things and see if your issue goes away. Have you had the car scanned since buying it? Are there any dash lights on? I would have the car scanned as well for good measure.

**BillBoost37** · 10-28-2014

I'm with Joe on cleaning.

As for on-star... look for the module in the trunk. IIRC they still had it there in 2006

**SuperslowGP** · 10-28-2014

04+ body style had the FIN antenna on the roof for the on-star. I may be wrong on saying they only came that way, but I have been around a ton of them and everyone with on-star has that FIN on the rear center of the roof. +2 on the TB cleaning, each 3800 I have had seems I needed to do it.

**newmans1985** · 10-28-2014

I had the car scanned by my neighbor who has a $5000 tool but we didn't get to far in depth. It was showing misfires in some of the packs. There aren't any dash lights on. I will try cleaning the TB. I will check the stuff for the onstar but like I said I think the previous owner took all that stuff out before they traded it in.

**BillBoost37** · 10-28-2014

It's nto the type of stuff you take out.

Why not run your vin past a dealer and ask the parts department for your RPO or option code list. That'll show if you had it or not.

**markpa** · 10-28-2014

Just changed the plugs in my 07 Grand Prix gt and now have a misfire and a light on. Are they picky on plugs. Put the champion iridium in.

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**stocker** · 10-28-2014

I think those plugs would be fine since they are iridium...

Did you get the wires back on the correct plugs?? Seems like the most likely possibility since that was the last thing changed.

**markpa** · 10-28-2014

Yes right lugs as I did them 1 at a time. They came off damn hard so I wonder if a wire got ruined.

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**markpa** · 10-28-2014

Plugs.

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**Fivefingerdeathpunch** · 10-28-2014

Maybe one is cracked, but without knowing what cylinder it's hard to guess at it.

I personally wouldnt run champions in a GM, thats more of a mopar/ford type plug in my eyes.

**Russosaur** · 10-28-2014

Originally Posted by markpa

Yes right lugs as I did them 1 at a time. They came off damn hard so I wonder if a wire got ruined.

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If you didn't get new wires you probably damaged the old ones. New wires are cheap like 25 bucks with lifetime warranty.

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**markpa** · 10-28-2014

Turned out to be 3 bad plugs with cracked ceramic. Got wires and moved 2 coil packs around ad still got the same misfire on the same cylinders. Took the champions out to return and put in acdelco. Misfires seem to be cured.

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**newmans1985** · 10-28-2014

Apparently the problem was caused by a vacuum leak going to the egr valve. It's amazing how something so small can cause such a headache. As far as the onstar stuff is concerned I was feeling around the headliner up by the mirror and there seems to be a hole where a wire should be going through.

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