I have to drive about 175 miles to a job this morning. I've got the cruise set at 75 mph, and after about 45 minutes, my speedometer jumps about 10 mph and my cruise shuts off. Then it starts going nuts. The speedometer was jumping all over the place. It would go all the way up to 160 mph and my HUD was saying 199 mph. When this would happen the RPM's would go up by about 300 and then once it stopped jumping around, it would go back to normal. I didn't notice any surge in my speed or RPM. It did this off and on and when I got off the expressway, when I stopped at a light, it stalled. I started it back up and I was driving through a town at about 25 mph and it stalled again. I pulled over and started it back up again and it was fine the last 10 minutes of my drive. And when I drove to the hotel this evening, it was fine. But, it's only a 5 minute drive.

Anyone ever had crazy crap like this happen before?

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

considering we are both in michigan and have the same color car but mines a gtp . . maybe we should just trade ! problem solved lol

Mine was doing the same thing when the TCM went out. If so, soon the transmission will start 'forgetting' what gear it's in. The transmission temp on the DIC will have '--' and the mileage will read 'Mileage Error.' The swap was covered under warranty.

This will be my forth trip to the dealer with this car for warranty work and it only has 30,000 miles on it. My 04 GPGT has 127,000 miles on it and besides upkeep, I only had one warranty trip with the car. This is my third GP, and it's probably good it wasn't my first, or it probably would of been my last. I had a 2001 SE, never had a problem, put 100,000 miles on it. So I upgraded to a 2004 GPGT, and now I buy the top of the line GP and it is the worst so far.

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

http://s380.photobucket.com/albums/oo24 ... =001-2.flv

GXPs in general don't have many problems, but there are some very bad seeds out there...

What is a TCM?

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

Transmission Control Module

Ok, the dealer found the problem. When the jackass (me) installed the K&N, he must have put it in where a wire on the TCM was being rubbed. Over time, it went through and caused it to start shorting out. Just so happens that the wire was for the speed sensor. It cost me $145 since it wasn't a warranty issue. And to be honest, I'd rather pay it and have some faith back in the car. I was thinking for a second that I bought a lemon.

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K&N CAI/Flips Custom Headlights, Tail Lights, Reverse Light,Brake Light/Front STB/Magnaflow Exhaust

2008 Grand Prix GXP

glad to hear that the fix was easy and pretty cheap!

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