Rpm and weird sound when accelerating

[Labbejenny]

Hello, I was wondering if something similar happened to any of you. Just to let you know that I already got my car check in 4 differents dealerships and various other garages and no one seems to find the problems.

First one, sometimes (well I mean at least once a day) when I stop at a red light my rpm start acting up. It goes up and down kind of aggressively...

Second problem, my car make a weird squeaking/chirping sound when I accelerate. It used to be only from time to time and now it's all the time. Again, no one can seem to figure out what the problem is...

I'll really appreciate any help thanks in advance !!

[Johnny Mullet]

The chirping/rattling sound could be from worn exhaust hangers. Common issue with the rubber exhaust insulators expanding and making noise. Not sure about the rpm issue. Do you have a check engine light on?

[Labbejenny]

No I don't have any lights on at all.

[klroger]

The chirping/rattling sound could be from worn exhaust hangers. Common issue with the rubber exhaust insulators expanding and making noise. Not sure about the rpm issue. Do you have a check engine light on?

Yep, Johnny's got this for the noise, also check the Alternator belt tension. They can make cool noises & still feel petty tight. Foama has a DIY here https://mirageforum.com/forum/showthread.php/4028 that helps with the proper tension... As for the revs up & down, check for vacuum leaks but other then that, I got nothing... Some here have used Techron injector cleaner with good results & cleaning your MAF sensor may help... I dunno... sorry... Maybe let us know what year / mileage / etc your car is & the Pros may be able to help...

[Labbejenny]

I'll check all these options then ! I forgot to mention that I have a 2018 GT at 128k km (I'm the only owner)

[Fummins]

Are you pumping your brake pedal when stopped? That will cause your rpm to go up and down.
I'm with the others for the chirp, likely loose belt. I don't do what everyone else does to check tension...Start car, turn on all accessories(ac,rear defrost,headlights), when ac compressor is engages(center part of pulley spinning),watch the top of the belt where it runs from the alternator down towards the crank pulley(lowest rear pulley). If it flops up and down it's too loose.

Or could be one of the two rearmost exhaust hangers(2017-2018 or 2020). The rubber holes wear out and cause the exhaust to give off a weird resonance/vibration.
Other shot in the dark would be if you had a trailer hitch. I had one car that drove fine until I made it a few block then the car would vibrate under light throttle or when stopped in drive. The tailpipe was hitting the hitch, likely from an accident...

Last guess, loose air cleaner. The rubber grommets wear out and the air cleaner flopps around. The end of the air intake snorkle is known/common to wear out where it slides into the air cleaner assembly too.

[mitsumi]

Squeaky noise
1. Check Belt
2. Exhaust Hangers
3. Exhaust Seal Ring

[Akafrosty]

I got this same rpm issue any update ?

[Akafrosty]

I have the same problem let me know an update , it rarely happens but when the AC is on it happens more often

[Eggman]

I got this same rpm issue any update ?

I have the same problem let me know an update , it rarely happens but when the AC is on it happens more often

Post a video of the symptoms.

1. Record video
2. Post to YouTube
3. Use YouTube video link to post to the forum by selecting the icon that looks like a strip of film.

That way we might have a chance to better help you.