2001 Monte Carlo is revving in idle, chugging along, making me sad


#1

Hello,
I have a 2001 Monte Carlo that I absolutely love. The check engine light has been on forever, despite repairs that should have turned that light off. Just recently, my car has started to gain RMP while I’m stopped or going anywhere between 0-25 miles per hour. This also makes the car physically shake and jolt. Very unfortunate. I turn it on to drive once more and then my check engine light flashed and beeped at me. I thought about waiting to take it in until Monday, but now I think it is best to bring it in now.

Thoughts of what it could be? I am a preschool teacher, so fixes above ten bucks will make me sad, but I’d rather pay some money now than a fortune later.


#2

Until someone checks for stored trouble codes, it would be impossible to guess the exact source of the problem. Since the CEL has “been on forever”, don’t be surprised if there are multiple trouble codes that will require multiple fixes.

While I don’t want to give you false hope, I will give you one possibility that is a very low-cost repair option. A disconnected or leaking vacuum hose can lead to fluctuations in RPMs, and can cause an engine to shake and jolt. If that is the problem, fixing it should cost less than $10–if the mechanic spots the exact problem quickly.

However, you could have a problem with the Mass Airflow Sensor (MAF).
Cleaning the MAF is cheap, replacing it will run into a bit of money–perhaps $150-200 for parts & labor, depending on your locale and your mechanic.

Or…Quien sabe?

All of that being said, when a CEL flashes/blinks, rather than being steadily illuminated, this means that the engine needs immediate attention, as there is a misfire taking place in the engine and continuing to drive it in that state WILL lead to expensive engine damage–so I am very glad that you are taking immediate action.

You didn’t tell us anything about how the car has been maintained, but I suspect that things are not necessarily up to date in that department. Poor maintenance can lead to a cascading sequence of problems, so I would not be surprised if several things need to be done in order to make the engine run properly again. Even though this will may not be cheap, deferring things at this point will inevitably make repairs even more expensive.

Please report back to us on what your mechanic comes up with as a diagnosis.
Try to get the exact trouble codes (the format is similar to “P0123”), and we can try to give you more specific advice based on those codes.

Good luck!


#3

As VDCdriver notes, the error code(s) would go a long way to helping out.

I will just mention a couple of things in the same vein as a vacuum line problem. One would be a dirty/gunky or binding throttle plate and the other a sticky/defective idle air control valve. Your symptoms basically suggest too much air getting into the engine. This creates the revving & the jolting is the engine trying to stall and/or fighting the brakes.

So the first order of business is getting the codes. There’s a good chance you might learn about a lean engine condition (for which perhaps someone replaced an oxygen sensor). Second, unless the code(s) clearly point elsewhere, is checking for vacuum leaks. Third would be cleaning all of those things mentioned - MAF sensor, throttle body, idle air control valve.


#4

Thank you all for the responses. I do try to keep up my maintenance with this car, as I favor even the 500 dollar fixes over the possible 3000 dollar fixes by ignoring the problem. My mechanic called with the initial diagnosis, suggesting it needed a tune up and the third cylinder is misfiring. There is also suggestion of a coil that may need replaced? Not sure if this is making sense to you all that know more than I do.

Tomorrow I will call back with what I want to be done. Definitely going to suggest doing the tune up to fix that cylinder problem, but could that also rectify the possible coil issue, making it so I wouldn’t have to replace it?

Thanks!


#5

It is very possible that merely doing a “tune-up” (presumably replacing spark plugs and all filters, or in other words–normal maintenance), coupled with replacing the defective coil (presumably the one for cylinder three), will take care of the misfire that spurred the flashing CEL and the shaking engine. Just be sure to have the mechanic check/clean the MAF, IAC, and throttle body while he is under the hood, and there is a strong likelihood that you won’t have to bring the car back for another repair attempt.