Thread: Really rough idling and choking on acceleration.

Hey guys. Looking for a little help. My 2000 Grand Prix GT 3.8L V6 has suddenly started running really rough. It's sounding like an dump truck @ startup and has an exhaust type burning smell. When I accelerate the tach goes to approx. 3000rpm @ just before 20mph. Once it changes out the tach drops back to normal and repeats this process upon the 2nd changeout. After 2nd changeout it accelerates fine but still running really rough. Has a bad shake when first accelerating. I just changed plugs & wires approx. 7 to 9 months ago. I swapped coil packs around and no change. I also disconnected battery and unplugged MAF sensor, let sit, reconnected battery and started. No change. I'm kinda lost @ this point other than thinking catalytic converter, (which I hope it isn't) or somehow all the coil packs are bad. She's always ran excellent, would appreciate any knowledge or help towards this matter. Thanks in advance.

Any engine lights on?

Yes. Check engine light has been on for a long time but, never had a problem. However, since problem started, if I try to drive it check engine light starts flashing.

could be a clogged cat, reach under the car and bang on the cat, if it makes noise like stuff's bouncing around in there its dead. also at night drive it around for a bit and see if the cat is glowing red, if so its shot. and you could pull the o2 sensor out and drive it, see if it is better, yes this will cause an exhaust leak but if it runs better you have a bad cat.

I was afraid it may be a bad CAT. I already have it up on the ramps right now. I'm about to go bang on it and see what happens.

Okay. Just went out and banged it real good. Didn't hear anything significant sounds other than loose heat shield. I'll try the drive it around and see if it's red afterwards once it gets dark. Hopefully It'll be something more simple than the CAT although I'm starting to lean towards that way.

my car had a clogged cat and felt like it didnt wanna go any where....it would bogg down it also smelled really bad

just for future reference, and not to be a dick, but anytime your cel is on, your car is having a problem that should be addressed asap or as soon as funds allow, getting the car scanned is free at most auto parts stores. a free scan could save your engine from blowing up if you let it go as ahh it still runs ok.

when the cel light is on you are not getting all the performance or mileage out of your cars full potential. once you get this figured out im sure your car will thank you by running like you never felt it run before.

I understand. However I did have it scanned @ one point and I was told problem was MAF sensor. A couple of months later it died on me and I could'nt figure it out (I actually posted problem on this site) wound up taking to shop and they replaced ICM and told me that MAF sensor was fine. So I just kinda didn't pay the light any attention anymore. I know I probably should've and will from now on.

so you had a shop fix it and they gave it back with the cel still on? if thats the case, avoid that place from now on.... that's some real BS

take your car to auto zone or another parts store that does a free scan and find out what your cars problem is. they will give you the code , and most will tell you what you need to do to fix the code, if they dont then post the code here, someone will know where to point you to.

Yes that's exactly what they did. Thanks for the info. I'm about to take it to Autozone right now and see what I come up with. I'll be back shortly.

Originally Posted by Flava601

Yes. Check engine light has been on for a long time but, never had a problem. However, since problem started, if I try to drive it check engine light starts flashing.

The engine light on is telling you there is a problem

Here's what happened. I just wasted $200 bucks. Took to Autozone to have codes read. Came back with codes PO102 & PO300. Was told problem would either be in ignition system (plugs,wires,coils...) or MAP sensor or MAF sensor or both. I came back home and thought about it a while then went back and purchased both MAP & MAF sensors. Installed them (with battery disconnected) and problem is exactly the same as before only now the check engine light is flashing as soon as I start the engine. Kinda downhearted right now. I'll pick my brain a lil while more and then I guess it's off to dealer in the morning. (ouch)

the flashing cel is the po300 multiple misfires, you need new plugs and wires. check the wires to the maf and map.

how long did you have the battery un hooked? sometimes it needs to be off for 30 minutes to an hour to clear the codes.

Didn't have it off quite that long. About to disconnect now and wait til morning. Kinda discouraged right now. I hope this works. Why would my plugs and or wires be bad? Not even a year old?. Gonna try it anyway. Really can't afford dealer right now. Especially after $200 hit. I got my fingers crossed.

Flashing SES light means MISFIRE.

As in plug and or wires issue!!

Okay five finger! I hear ya! You really made me feel a lil better because you sound as if that is exactly the issue. I'm gonna pull those plugs and inspect in the morning. I still can't help but wonder (if they are bad) do I have another underlying problem because they aren't even a year old. However, I hope that is the case because it'll be the least expensive.

Hold up guys..

first off, flashing CEL means possible catalyst damaging condition. Sure 95% of the time it's plugs/wires. Let's diagnose this though.

When we suggest pulling codes, we suggest pulling them and posting about it. Not shotgunning parts, when you are unsure and before you post again. Probably lesson learned, unforutunately a pricey one.

P0102, go look that code up and see what it says. Then keep in mind, we don't know if the 102 is current or history. That might be from when you unplugged stuff.

Which plugs and wires did you put on the car when you changed them last? Brand and model number on the plugs please.

Hey guys! Update time. I did some more checking into it before I gave up early this morning (1/30) and took it to dealer. (Plugs were Bosch gapped @.060 by the way) Problem turned out to be ICM (ignition control module). I'm glad "Da Baby" is back puurriing like a kitten again but, I'm still confused. Earlier in this thread I mentioned a technical question I'd posted here a while back and we never figured it out so I took it to dealer. Problem was "ICM" that time also. This was maybe a year and some months ago. Still to that detail, that was the 2nd time!! In other words I've had ICM changed "4" times (3x dealer - 1x me) in last two years. I asked dealer if there could be some underlying condition that could be causing this. They simply told me that they had performed a full comprehensive diagnostic test and only fault throughout entire car was "ICM". I'm glad she's back right but, has anybody else out there had similar problems with ICM? I don't think they would be designed to fail that quickly. I would love to discuss this and try to figure a reason for this. Thanks again for everything. I hope I can be of assistance to someone real soon! Some real professionals on this site!