95 monte idle problem any suggestions

[kenbarnesjr]

When I start my 95 monte carlo (3.4) it revs high to about 4 or 5 and then drops. it continues to do this until it gets warm even cutting out if i dont hit the gas. just changed the dile air control motor and it's not that. Could it be the spark plug wires are old or something to do with fuel injection. Need help if anyone had similiar problems

[Woodstockx]

Originally Posted by kenbarnesjr

When I start my 95 monte carlo (3.4) it revs high to about 4 or 5 and then drops. it continues to do this until it gets warm even cutting out if i dont hit the gas. just changed the dile air control motor and it's not that. Could it be the spark plug wires are old or something to do with fuel injection. Need help if anyone had similiar problems

I have A 95 3.4 DOHC doing the same thing. From what I've learn, Its either the Intake or Head Gasket. I tryed changing the all the sensors you can think of, and the idle still has a mind of its own. It doesnt stall, and will start fine. But after it is placed in gear, the RPM jump anywhere to 3000. It is driveable but you are off to the races. At times it will run normal, but it I shift (automatic) into park it RMP's race off again. I had it into a dealer and he said its a vaccum leak. On top of this, it leaks oil from somewhere around the rear head.
At this time I have the intake off and I am hoping that by replacing the upper and lower gasket , this will solve both problems. I have found anti-freezze in the top of the rear head. But there is no water on the dip stick. There is however water in the plugs.
Being DOHC I really dont want to pull the heads. I looked though this site and found several idle issue that end up being the intake gasket. I also dont have the tools needed for that job.
I dont know if this info helps you. But your not alone in this.

[Woodstockx]

If anyone has any other info. or a similiar issue please reply.

[wrightz28]

I think you're right on track.

[ChevroletTough]

I am having the same problems. I also own a 1995 monte carlo z34 (3.4) DOHC. Tomorrow I am taking out the PROM chip (in the computer) and brining it into a dealer to see if there is an updated chip. I have a very close frend whos a mechanic (I trust him with everything) who reccommended looking into this. The GM dealer should be able to see if there is an updated chip and he said it should run anywhere from $75 to $125. Ive done some reserch and found that this cold start issue has been common across certian GM models, and an updated PROM has fixed the issue. I guess I will see?

When the car is started up, it does not run off sensors, it runs of the "stats" inside that PROM chip. When the engine gets up to operating temp, it will run off the sensors readouts.

I have already replaced the intake gasket, fuel regulator, one injector, camshaft sensor and an O2 sensor.

Don't get me wrong. I am a GM fan down to my bones, I have a bowtie tattoo on my arm wrapped in barbed wire, but this series of engine is NO GOOD!

I will post what I find out!

[ChevroletTough]

update: I went down to the local dealer and ordered an updated PROM chip, $100 shipped, will have it soon. There was a bulliten posted for the car, and one of the updates was a cold start issue.... please fix my car.......I will post the results!

[ChevroletTough]

Installed the updated PROM. Didn't change a thing, actually my car dies in the morning now.......

WHAT THE HELL IS THE FIX?!?!

[wrightz28]

Was there a relearn procedure to perform after the PROM was installed?

[ChevroletTough]

not that i know of, its the old style chip, that looks like a piece of RAM in a computer, i just swapped the pieces (of course disconnecting the negative terminal on the battery before doing anything!) The relearn process should be instantaneous right? On startup, the car uses that PROM chip to determine how much air, fuel and yadda yadda yadda to give the car, after it warms up it runs off the sensors.

My car idles terribly, 800rpms to 3k rpms and sputters and when i go to drive it, it feels like theres no power, sometimes i can hardly brake. After it warms up the car runs fine.

Ive been fighting this problem for 3 months now.

[wrightz28]

I'd double check with the dealer of puchase on that.

As you elduded, you know what's going on at startup.

However, I normally, any time after power has distrupted for a period of time to the ECM drive the vehicle under all 'normal' operating conditions as the running history has in most cases been lost. This would included stop and go, cruising, some highway (or as close to) speeds.

At startup tho, a few sensors are used for the cold start mixture, the intake air, engine coolant temp and MAF.

[ChevroletTough]

Funny thing. Today it started just fine and ran like a charm.... tomorrow is another day of test.

Is there a relearn process? I was almost sure it was just an instentaneous thing? Ive read alot about this problem, but have found no answers. I replaced the fuel regulator, head gaskets, one injector, a vaccum line, cam sensor, O2 sensor, and a side marker socket and ive only owned the car about half a year maybe....

the fuel filter got clogged and caused a injector to go bad ( i think) and the fuel regulator to go bad. So that was party my fault for not checking that.

I'm only 21, but i feel i know enoguh about cars to do alot myself. Ive replaced the tranny and engine in my 89 silverado, gosh i love working on the simple stuff, i can literally sit in the engine compartment on that beast! (350cu)

if you have any other ideas let me know!

[ChevroletTough]

It started up awesome today!

We'll see if it actually needed a relearn process, i'll keep this post up to date.

Maybe i finnaly found the problem????

I've talked to alot of car people/mechanics and done as much reserach as I can find on this topic. I've read alot about cold start issues with this motor (3.4) Sometimes its the intake gasket leaking, sometimes it needs a PROM update. Ive already done the head gasket replacement, that didn't work. Then I did the PROM chip update, its very simple, just make sure you disconnect the batter before even touching the computer

I hope my good luck keeps running!!

[richtazz]

An intake leak can be determined by spraying starting fluid or WD-40 along the seam of intake/heads. This PROM update issue is interesting. Keep us informed if it continues to run correctly.

[BwhatdoIno]

[I hope my good luck keeps running!![/quote]

I have the same car, same exact problem. Before I found this forum, I replace the mass air flow sensor, the idle air control valve, plugs, and soaked (what I could reach of) the intake manifold with starting fluid - but nothing made a difference. I finally parked the car now that Winter is here - it's completely helpless in the cold. It won't run right until it reaches @ 160F, by then I'm already there... I was skeptical of the PROM chip change working, but now I'm getting hopeful - Keep posting ChevroletTough!! Thanks

[ChevroletTough]

There are good days and there are bad days.... Im completely confused. Some days it runs fine on startup and some days it doesn't. Im going to look into it further. Its almost like my car has a short somewhere, somedays it runs fine and other not... Today is a new day.