I used to drive a 1995 Regal GS. And then I needed a new car, so I bought a 2005 Bonneville GXP with 46,000 miles in good condition for $15,500.

So the other day I was making a left where two turn lanes make a left. I pull up fast and brake hard at the red light, and there'* this Ram 3500 Cummins turbo diesel, so we take the turn and I gun it to pass him so I can get into my turn lane to go home, reaching 6500 rpm in the process in first gear.

Then I come to a stop at the next red light, and the engine is fine, till I feel a bump. So I'm like wtf? Does someone have an insane set of subs in their trunk next to me? Till I realize I'm not hearing any bass and that is coming from my engine. Then I feel another bump, and another (gradually increasing the frequency of the bumps), till my engine constantly idles really rough, to where you can feel it shaking the car. Acceleration at low RPMs is very rough as well, with some apparent hesitation, and my whole drive home on the highway I was getting no better than 19mpg at 65 mph. I also had a noticeable decrease in power from before, and the service engine soon light was blinking.

Oil level is fine. Everything seemed fine, it just didn't *feel* right. I took it into the dealer that I bought it (a Nissan dealer), because I had bought a 4 year/48,000 mile powertrain warranty with a $50 deductible. Unfortunately, my warranty wasn't processed yet so I couldn't use it to get my car fixed. It will probably be another week or two till I can take it in.

So I'm sitting here wondering what in the world could the problem be. My Regal GS with the L27 engine has 172,800 miles on it and I've been riding on wide open throttle for 100,000+ miles and never had so much as an oil leak.

Anyone here have any ideas what could be wrong? If I can fix it myself for $50 or less, I'll just do that instead of taking it to the dealer and arranging for someone to pick me up. I can rent a code scan tool to see what code my car is throwing out for the problem if that would help anything.

I'll be interested in hearing what it turns out to be. The mechanical end of things is not my strong area, but with that high an RPM along with the unsettleing noises it just doesn't sound like a $50.00 or less repair to me.

Sorry to hear about your experience. Keep posting the details

So far the guys over at w-body.com have suggested that the problem could be related to a bad spark plug, spark plug wire, or ICM/coilpack.

I really wouldn't know. I'll have another look at it tomorrow after work.

Just FYI, whenever your CEL is blinking like that, you gotta PULL OVER RIGHT NOW!

Seriously, that'* like the car'* last line of defense. If something'* DEADLY wrong with the car, it'll blink. I'm thinking the outcome isn't gonna be good.... Luckily, ya got that warranty
Did it sound like a knock to you?

It didn't sound like a knock at all. Just felt like the car was idling really rough. the engine bumps started very rarely and then got more frequent till it was a sort of a rumble. I didn't hear any unusual sound beforehand. Just the lovely roar of a Northstar V8 hitting 6500 RPM.

I had to get home somehow, and even though I did pull over and check everything, everything seemed fine. I drove it for about 40 minutes that way, and nothing worsened. It feels a lot like a misfire. I'll get the guys from autozone to scan the code that the computer is throwing out so I can try to figure out what'* wrong.

And yeah, I am lucky I got that warranty. Although honestly, I'm somewhat doubtful that an engine like this would just completely fry itself off of one hard run at 46,000 miles. It must be something small. Chances are the previous owner never did replace the spark plugs either, and probably babied the car. Then I came along...

Either way, the powertrain warranty should fix whatever it is that'* broken.

I'd say coil pack or fuel pressure regulator. Simple fix if it'* either of them.

Simple perhaps, but certainly not cheap.

As I understand it, the coilpack on these motors is one piece for each side of the engine for 4 cylinders each, running $300 at NAPA. Luckily that thing is covered under my warranty, lol.

Are you going to tell me that you never rode a wide open throttle to its peak shift point in first gear? This certainly shouldn't happen on any engine at 46,000 miles. Its a disgrace in GM'* face if a $38,000 "Sport" Luxury Sedan blows any ignition component (aside from a spark plug) and starts misfiring at 46,000 miles from a few WOT redline runs, when my 1995 Regal GS "Granny Car" with 172,800 miles has been riding wide open throttle and 1/4 mile track runs since I bought it with 67,000 miles and hasn't ever given me a single engine problem (which I'm now using to get to work and back every day).

Perhaps you're missing my point, so let me clarify. When internal parts are going as fast as they are at 6,500 RPM and the engine is under the load it was at that time, the chances of a more catastophic failure are greater than when the engine is at low RPM and no significant load (therefore, logic SUGGESTS a more expensive repair). My comment is that simple. Nothing more, nothing less. I never suggested a failure should happen, nor did I suggest it is unreasonable for you to expect to be able to push your engine to this point. You are reading WAY too much into my post.

I wouldn't call it a disgrace yet until we hear what the problem is, and how many other Bonnies have had this problem. No one has ever had a problem with a Regal GS?

I had a similar problem with mine a while back and it turned out to be a coil pack. Mine didn't seem as severe as you are stating but the symptoms are the same.