Rnizz

My 97 Lumina is having problems at low speeds and idling. RPMs at idle constantly bounce between 700-1300. Giving it enough gas in idle to hold it at 2K rpms stabilizes it for as long as I give it the gas. Acceleration is difficult, jumpy, and inconsistent until it gets to about 30mph. At that point the rpms are stable and acceleration is more uniform but accelerating is still more difficult than before. This started the first time I started it after it sat unused in cold weather (10-25F) for two weeks. All fluids recently changed, no check engine light.

Also, probably unrelated but still unusual enough to mention, the power steering was barely working and I found the cap on the power steering fluid tank cap to be loose and the fluid low. Adding fluid and tightening the cap fixed that instantly. No idea how it came loose enough to lose fluid.

kevinkpk

Have you done anything to the air inlet system, maf sensor ect.? Pull and clean the air intake hose, and MAF sensor. Sounds like the idle air control is messing with it.

Rnizz

I haven't done anything yet, other than figure out the details of the symptoms. I don't know a lot about working with cars, but I am mechanically minded, and pretty good at working with guides found online. If I can confirm a diagnosis, I have an excellent success rate making repairs I've never done or heard of. When I get home I'll check out the air intake and MAF sensor and report the results.

kevinkpk

Check for air leaks, cracks ect. You clean the maf with maf cleaner found at auto parts store

Rnizz

Having trouble getting the MAF sensor separated from the intake filter cover. The rubber is gripping the MAF quite securely and I don't want to manhandle it and break something. Anyway...

Hoses are good. Soft, pliable rubber, tight seals. No detectable air leaks
​​​​​​
Intake filter is filthy, brown, crusty. Definitely replacing that.

MAF has visible white crusty corrosion inside. The tiny wires look clean, the bars they're attached to have visible rust.

I've got errands to run, I'll get an intake filter and MAF cleaner while I'm out. If anyone has advice for getting the MAF off the intake filter cover, I'd love to hear it. I have a variety of lubricants, but don't know which (if any) are safe to use here.

kevinkpk

WD-40, with the straw, put it in between the tube, and maf. won't take much, but that should free it to come out. The idle air control is the bypass underneath the intake tube, odd ball looking thing (it's integral part of the inlet system). Make sure there are no leaves, debris ect. in it.

kevinkpk

That may be all it needs, I'd still clean the MAF, and the other things I suggest in the previous post. The engine could be having a mechanical problem at low rpm's , just because of low rpms with running smooth as it should.

Rnizz

Alright, done. Replaced the filter and cleaned the MAF. The idle air control looks good, at least from what I could see. It's improved, but not all better. I'm thinking one of two things.

​​​​The IAC valve is either not working or barely working, that's not something I would be able to tell from the look I got at it.
OR
Intake problems have caused deposits on spark plugs, causing misfires.
How difficult would it be for an amateur like me to fix those?

kevinkpk

That's not an issue, the alternator isn't putting out as much due to the lower rpm. You say better, what's improved, and what hasn't? Have you changed the fuel filter? After your post about the air inlet filter, this is one thing to do anyway.

Rnizz

It's accelerating much better, even at low speeds, but still idling very rough. I have not replaced the fuel filter, but it has been replaced in the past year.