92 q45 idle jumping

[bigox777]

Hey everyone! In the past 2 months I've done a lot to the 92Q. New transmission, alternator, battery, master cylinder, fuel pump, etc. I just put in a new trans. and had a small problem with it after i got it back, so I brought it back in and they put on a new speed sensor. I got the car back 2 days ago and now I'm having a problem with the idle jumping up and down while i'm at stoplights. My Q always idled around 600. When I stop now it jumps up to 1200 and then drops down to about 200. It repeats this 3 or 4 times then drops so low it feels like its ready to cut off and the low battery light comes on. I just tap the gas and the light goes off. If it makes a difference, I'm on the east coast and it's freezing here.Between 12-30 degrees for the past week. Anyone had this problem before? I need your help on this one pretty quick because i have a pretty long drive with a lot of stop lights going to work.Thanks in advance!

[DAEDALUS]

Jiggle the MAF sensor connector while the idle is jumping to see if it clears up.

[PalmerWMD]

Big,

I have had this symptom before, with a cold engine,cold transmission, very recent rebuilt transmission.turned out transmission was low on ATF.

Even when shows kinda ok on dipstick.When very cold ATF contracts, if it's even a bit low to begin with.....then..

I "think" if your symptoms are at all like mine were, the transmission may be failing to release and trying to stall the engine cuz of low fluid.

Might be worth a try, to check transmission fluid on even terrain when first start of day, brrrr.

If low, fill up and see if it helps.just a cheap low tech attempt.

Fred...

[PalmerWMD]

PS: Problem goes away when engine plus transmission are fully warmed up right?Or do they not get fully wamr during your commute?

Fred...

[bigox777]

The car dosn't warm all the way up for a while in this weather.I found it to be worse right after i pull off the highway

[PalmerWMD]

Actually when I had this prob the delaer just added a quart of ATF when I told him the symptoms and that it was recent rebuild...

Worth a try I think, unles your early morning fluid clearly seems topped off.Actually mine seemed full but teh addition of a quart cured prob anyway.

Not saying its excat same problem, but symptoms seem very similiar (my transmission didn't wamr up until a full 15-17 min drive in very cold weather).

Fred...

[bigox777]

I'm going to add some fluid and see what happens first thing tomorrow morning. My Q also takes a good 15 min. to warm up in this weather, and they say its going to be 3 degrees with the wind chill tomorrow. Thanks for the advise and I'll let you know what happens tomorrow night.

[PalmerWMD]

PS:

Sorry for all my typos, my ergonomics are horrible here.

I actually <do> know how to spell, though one would never know it judging from my posts here.

Fred...:oface

[PalmerWMD]

if u add any ATF try to add MOBIL1 syn ATF for better cold behaviour while u r at it.

Fred...

[landtodd]

Don't forget the MAF connector, as Daedalus rightly pointed out! Very, very common problem.

Incidentally, mine acted up about a month ago. Cycled and cleaned the MAF connector, and the idle problem vanished. When/if it returns, I'll replace the connector. The new & improved version has an external pigtail connector for ground, according to Dennis.

[bigox777]

Today when I started the car cold, it turned over and then the idle jumped up and down until the car cut off. I checked the trans. fluid and it was full. So I messed with the MAF conection and all of a sudden the jumping idle is gone. The Q is idleing around 550 in gear and 650 in park. I never really got it to warm up today even after a 45 min. ride each way to work because of the temperature here ( under 0 degrees with the wind chill !!!).I hope it did the trick and thanks to everyone with the quick replies and great help.

[PalmerWMD]

that's great news!

We been rooting for 'ya.

Fred...

[fxjackso]

Big Ox-

Check your thermostat. I'm in the same area as you, and with a new t-stat our 90Q warms up and stays right where it should. When I removed the old I could see where the rubber seal had deteriorated, allowing (cold) coolant to get through.

[Q451990]

Ditto on the Thermostat... they all tend to loose the rubber seal around the edges with a little age. Mine wouldn't stay warmed up on the interstate at 20F before replacement. Just make sure you have a new hose on hand to connect the t-stat housing and metal annode pipe when you replace it.

It's actually pretty important for the car to warm up completely for the ECU to come out of "warm-up" mode... The car will run rich until then, possibly causing catalyst damage.

Heath

[Q45tech]

If your car doesn't warm up in 10 minutes of driving [even at 7F SOAK tested today] and the heater runs any higher than 2 symbols at 78F setting at 7F even at expressway speeds [70 mph] you have thermostat problems.

Now there could be a little variance but even 20% would be only 12 minutes of driving........obviously city driving would vary more.