I had a coil pack replaced as well. Rough idle + SES light.
Hopefully that'* all it is.

i may have missed it, but get the codes read! you need to find out why the CEL is on

Hmm, I'll have to get it checked with a scanner tool then. My guess was also that it could be a coil pack. I had also heard the coil packs on these things are $300 to replace in parts, which is why I've been a bit hesitant to try to fix it myself, especially after learning that the car does indeed have a Deluxe bumper-to-bumper warranty and that I can get the problem fixed once that warranty kicks in. The car is currently parked and not being used. People on the cadillac forum had told me that the blinking SEL light meant a severe misfire and that I could damage my cat if I continued to drive it.

As far as nothing happening to a Regal GS, well I am referring to a 1st gen naturally aspirated L27. So far nothing has happened to *mine* and I've been heavily abusing that engine. I just rolled into 173,100 miles. I just thought it was a bit ridiculous to be getting an engine misfire at 46,800 miles by comparison. Luckily the warranty will cover anything and everything wrong with the car.

You Know.....I see alot of blind speculation here. Some by people who dont even know the components of the Pontiac LD8. The engine runs on 8 individual coil packs that plug directly onto the sparkplug. (Have any of you even taken the plastic engine cover off ???) There are no sparkplug wires and the individual coil packs are plain as day. I cant even find it on NAPA, Advance, or Rockauto sites. They all incorrectly list and/or show Caddy type coil packs which use spark plug wires, and apparently where some "armchair" Northstar mechanics are getting their info.

I take my GXP near the limit continuously, no problems, the 6500 limiter is both a pain at getting better performance and a blessing for longevity. Reading through the posts, I have two thoughts. One is 6500 RPM in not enough to fold up a fresher Northstar engine. Second is that its good that the engine is getting the SEL light. Its when the engine is fouling and doesnt send a code, things tend to be on the catastrophic. The SEL is a catch all system and it could be one a dozen/more problems. And guessing here by the symptoms given doesnt help anyone. You said the car is under warranty, right? Well get it to the dealer and let them fix it and get back to us. If its under warranty, the prices dont matter. You could get the code read at Advance Auto for nothing and it may help, but to fix something on a GXP Northstar for $50 aint gonna happen. Better get it to the Dealer. Since we are all "Blind Guessing" here, my moneys on coilpack/plug issue.

This is my first time on here, and unfortunately for the exact same reason. I have a 2004 GXP with 28,000 miles.--I only live 2.5 miles from work. On the way to work on Fri., Feb. 29, I noticed it running very rough and the SES light came on. Same thing on the way home and then SES started blinking. Took it to the dealer today, Mon. Mar. 3, and for $80 all they could tell us is: "Missfire Codes Set #4 cylinder test injector coil, and plug all ok. Test compression, no compression on #4 cylinder." Brought it back home today and will contact Pontiac before proceeding, since it'* out of the GM warranty. We've done all of our own oil changes every 3K miles. The salesbook from when we purchased the GXP states: "The 4.6L Northstar V8 is deisgned to go up to 100,000 miles before the first scheduled maintenance." Prior to this, I had a 1996 SSEi with no problems whatsoever.

Given that I haven't seen too many other people with this problem, I think its safe to assume its not a very common problem. Lucky enough for me, I have an extended warranty to back me up. I'm only hoping I run into every possible issue with this car while its under warranty so that the defective parts can be replaced with higher quality parts that won't break down in the same manner.

I'm also glad to hear that you do your own oil changes. I haven't yet had to change the oil in the Bonneville and I used to do it each time on the Regal, so it will be a breath of fresh air to know that at least the oil changes on this car can be done in my own garage.

Then again, does the oil need to be changed every 3000 miles? Or am I safe to drive it till my oil life percentage on the car'* computer drops below 5%?

I'm sorry to hear about your problem though and that you're out of warranty. Unfortunately, advertised claims are not always equivalent to official vehicle warranties. If you do manage to riot your way into a free repair, let me know and I might attempt the same. I will otherwise have to pay a $50 deductible for my repair.

I'll let you all know what ends up getting replaced on my GXP. I should be taking it in some time this week or next week.

I change my oil when the life gets to 10% That is somewhere between 7-8000 miles. I am interested to see what you find.

We contacted Pontiac, and were told they review these on a case by case basis when the car is out of warranty, and work has to be done at our Pontiac dealer. We were provided a case #. Took the car back to the dealer, and they found broken valve spring on #4 cylinder. Due to low mileage, GM covered the $589 invoice 100%! They wouldn't cover the $80 initial diagnosis fee, but it could've been a lot worse.

Got my car fixed, finally.

It was the Ignition coil that was replaced, the Cylinder 7 ignition coil having shorted out. The assembly was replaced with a new and improved one apparently. I got them to fix that, along with my temp gauge that fell (replaced the whole gauge cluster), and replaced the steering shaft with the new and improved sealed one.

Invoice: $1,227.43

I paid :$50

Man I love extended warranties.