RPM fluctuation

When I started the 97 GT, it went from about 2k RPM to about 1k RPM, back and forth. It sounded like it was going to stall. Anyone know what this is?

Hiya, as for the problem is this a usuall or just a one time thing?

It's regularly now. I just replaced the o2 sensor and when I started the car it was fluctuating like that. Now it does it everytime. I noticed that when it goes up to around 2k, the lights dim.

Sure the lights don't dim when it goes back down to 1k?

Yeah, you're right, they dim when the RPM's go down, not up.

That's normal. It's most likely unrelated.

Alright, new development. The car won't rev to over 4k. It bogs a couple of time and the needle just won't go over. I tried to redline it just to see if it would while driving and it won't. Also, it stalls when I stop and put the parking brake on...it just completely dies. Any ideas?

Are you throwing any trouble codes?
could be a bad computer, or maybe the engine is being starved of fuel. How does it run between 1-4krpms?

Even between 1k and 4k it still bounces erraticly (sp). I took it on the highway just now and I was going about 70, but when I floored it, it wouldn't go over 3.5k.

Dorley,

I have been having the same kinds of problems. I found the even thought the SES light didn't come on (or stay on) that I had thrown a code. I'm still working on the problem. I thought I had it fixed the other day, but to no avail. If you have an Autozone nearby, I would go there and have them scan your computer. At least then you'll have a place to start. I've replaced both O2 sensors on my car, cleaned the Throttle body and MAF sensor. Next I'm going to check the EGR valve. You may want to check all of those as well.

Hope this helps

I'll try all that stuff. It probably is all from 97 anyway, so it can't hurt to replace. Thanks for the tip, let me know if you figure anything else out and I'll let you know if I think of anything

hey to me your problem sounds a lot like a spark problem either plugs wires or distributer. or it may even be a fuel filter. u probably checked this already but just in case. if not maybe fuel pump or timing? just throwing ideas out there hope it helps.

hey before anyone corrects me cancel the distributer

Were you thinking about the ignition coils???

ignition module! or, it could be a coil, which three of our screwed down onto the module. it would be easy to try the coils from your other GP and see if that changes anything. maybe even the whole ignition module, but i'm not sure if those are the same.

yes i was thinking the ignition coils sorry

No problem.

Hopefully it isn't a exhaut comstipation issue. Check your CAT...

Crank position sensor or clogged cat is another possibilitiy

wow i am having this same problem! agh its so annoying. i want to take it in, but i know its gonna cost a million dollars

Im actually thinking it could be the IAC (idle air control valve). or the TPS (throttle position sensor). both are sensors located on the throttle body. I am going to clean my IAC tomorrow with carb cleaner ill let you know if that works. i might just buy a new IAC, only 25 bucks.

check for an vaccum leak or an upper intake leak or you could have a pully locking up or a mass air flow sensor, check for that and find out if your fuel pressure regulator is leaking.

The ignition module is usually a seperate piece, and it works or it doesn't. If you're suspicious of it, autozone has a machine that can check them for free, you just have to take it off and bring it in. Coils can be checked with a voltage meter to see if they're within spec.