GMC Envoy revving high



Before I call a local mechanic shop, I thought I would post my problem on here and get an idea of what might be the cause. We have a 2003 GMC Envoy. Normally upon starting the car, the engine will rev high for a few minutes while driving and then it stops and returns to normal. However, this morning I was driving the car and it was revving high continuously. Every time I started from a stop at a light, it would rev up to 2 RPM's and continue higher while the car was just sluggish. I would let off of the gas pedal and it would drop back down and slowly shift but then it would return to making a loud revving sound as I stepped on the gas pedal. There are no lights lite up on the dashboard and everything looks normal except for the loud revving sound and the car being sluggish because of the high revving.

What could this possibly be? I'm afraid to drive the car in fear that it may cause extensive damage. This has not been our year for cars after just sinking $1800 into our Tahoe for repairs.

Ugh! Is this possibly an easy fix and what should I suggest or know when I take it to a repair shop? I don't want them suggesting things that aren't the issue or over charge me.

Thanks in advance for your help with this.


Sounds as if the transmission is slipping or it is not shifting into gear at the proper point. It could be a solenoid, cheap and easy or a torque converter, expensive.


Does it ever rev high (after warming up) when your foot is off the gas?
If not then it sounds like the tran$mi$$ion is slipping.


I just started the car up and backed it down the driveway. As soon as I started it, it revved high but then lowered down to 1/2 an RPM which is normal. However, once I was down the driveway and then put it into drive, it started revving high again. Once I put it into park and then slowly stepped on the gas, as soon as I stepped on the gas pedal, it hesitated like it was going to stall or something and then it revved. It did that same thing about four times that I slowly stepped on the gas. Shouldn’t the check engine light or something come on notifying me that something is not right? Should I take it in to be looked at and is it safe to drive on the road to the shop?


We haven’t taken our car in yet to have the transmission looked at but can someone tell me a “ballpark” estimate of what it would cost to fix the transmission? My husband took the car out for a test drive and said he thinks the transmission is slipping. When you give it gas, it’s very sluggish and revving high. Aamco wouldn’t give me any kind of estimate over the phone. They would look at it for no charge but we are just trying to get an idea of cost from least possible problem to most expensive. Could you give us an idea from best case to worst case scenario on what we might pay to have this problem fixed? We just shelled out $1800 on our other car for repairs and we are deciding on whether it’s worth fixing this one, too.


Nobody is going to give you an estimate over the phone. This one needs to be diagnosed hands-on. And anybody who gives you a “best case/worst case” cost should also be avoided.

It could be as simple as a bad temp sensor or a bad IAC, or could be much more complicated and expensive. There’s no way to guess without looking at it. Minimum, the tech will have to scan the ECU for fault codes.


Has anyone at least checked the transmission fluid?

Just to double check - are you saying it will rev high while you’re just sitting without having your foot on the gas pedal? That would have nothing to do with the transmission. Or are you saying it’s only revving up high when you’re giving it gas? So, you hit the gas, the engine revs up, but the car is reluctant to move? That is a slipping transmission.

It’s a GM. There probably are error codes stored, but not ones that turn on the “check engine light.” GM is only worried about itself, not you.


I believe this car has an electronic throttle


Fer Gawds sake don’t take it to Aamco, or any other chain.


Check your transmission fluid when the car has been driven 7 miles or more with the car running in park. It could be just low fluid. Low fluid would be caused by a leak some of which would be inexpensive to fix, some more costly but not nearly as much as needing a transmission.


Cigroller, yes, the car only revs high as you step on the gas to accelerate. My husband believes it’s the transmission. Someone mentioned to avoid Aamco. Why is that?

It’s frustrating not knowing where to take our cars these days. We’ve tried chain shops and independent mechanics with bad experiences each time. Obviously, we want to take our car to an experienced transmission shop. We have to have the car towed there, as well, so that’s why we want to get some sort of idea of what we are looking at before we go through that whole process.

I would think that an experienced transmission shop would be able to give us some sort of idea of what “could” be the problem and how much it would cost to fix. I understand that nothing is set in stone and the estimate is just that. They deal with these issues all the time and should have some idea of pricing. I just can’t afford to tow it to one place and then if we need a second opinion or we aren’t happy with them, we have to tow to another, etc.

I appreciate your help. Just so frustrating and not having much car repair knowledge doesn’t help. :slight_smile:


Has anyone checked the fluid? If you have developed a leak and the fluid is low enough, the transmission will slip. Don’t go by whether there are any “puddles”. You can still have a leak without ever seeing any puddles. Furthermore, you say that it often returns to normal after driving for a while. This would be consistent with low fluid. Transmission fluid expands as it gets hot. So the actual dipstick level is much lower when the car is cold than it is after it is fully up to temp. If you look at the dipstick you will see that there are multiple marks on it that vary according to temp.

If you do just have a minor leak that has drawn down the fluid level, now the surest way to kill it (if you haven’t already) is to drive it while slipping. You will cook the thing with heat and extra wear on the clutches. If you find the fluid level low and bring it up to level and it drives normally then you can just drive it to a shop. If you add any fluid you use Dexron fluid only! If your owner’s manual says Dexron III then anything on the shelf that is labeled Dexron or “Dex/Merc” is fine. But if it says Dexron VI, the bottle must be labeled Dexron VI. Dexron VI is good either way since that is what GM now recommends regardless of what your manual says. It replaces Dex III.

This is one reason no one can tell you anything by phone (or by web without full info). Another reason is that what the transmission is doing is intimately connected to sensor information about what the engine is doing. A problem with, for example, the throttle position sensor, MAP or MAF can provide incorrect info to the computer which then results in incorrect line pressures inside of the transmission.

There is nothing simple about any of it.

The issue with AAMCOs is that - well, some say it stands for “All Automatics Must Come Out” - meaning that it doesn’t matter what the issue is, you will be told that you need a new transmission. Then the work you get from these places is often substandard. But this does vary - most AAMCOs are independently owned franchises, so their quality will vary a lot. You need to use some word of mouth about transmission specialty shops in your area. Ask around among people you know to see if you get any vague consensus on a shop that can be most trusted.



AAMCO is strongly motivated to sell you an overhauled transmission, whether you need it or not

For example, if they determine you just need a solenoid or speed sensor replaced, which might cost you $250 to repair, they’re STILL going to tell you the transmission needs a complete overhaul

They’ll never tell you about the cheap repair which might fix the problem


Check Mechanic Files for your area. I have had great luck following the reviews.


Question about checking the transmission fluid. I did check that the other day, although, the engine was off and cold. It was a reddish color and about 1 1/2 inches up the stick. Should I start the car and let it idle for a while and then check it while it’s running? I don’t want to move the car at all for fear it will make things worse.

I really appreciate your honestly regarding Aamco. That’s certainly what I don’t want to deal with. Thank you for the link the mechanics files. I will look through there.

You guys have been a HUGE help! :slight_smile:


The fluid needs to be warmed up and the engine needs to be idling

Otherwise the reading will be incorrect

The fluid needs to be in the crosshatched area


You can just check it cold because the dipstick should have a mark for that, and right now you just need to know if you’re in the ball park. “Fine tuning” the level is not your problem of the moment. The owner’s manual will give you the specific procedure. Some vehicles are supposed to be in neutral. Most are supposed to be in park. All have to be running. But you should cycle it through each shift position for a bit. So set the parking brake, start the car, shift it into L, wait 10 seconds, shift to the next position pause., next …up to D… pause. Then go to R and pause… Then back to Park. Then check the level.


Great! I’ll check the owner’s manual tomorrow and then try what you suggested.

Thank you, thank you!


How many miles on this car?


Almost 92,000 miles.