08 aveo ls fluctuates rpm on start

[Shrak]

I have had a bunch of issues with this car recently 130k miles. A few weeks to a month ago now I was having issue with the car stalling at parked idle and was to my best research able to narrow it down to it being the iac or tps. My version though doesn't have a norm al iac valve, as it has an electronic throttle body. So i order a new throttle body get that replace and now the car is running fine. No rough idle, nothing.

Now the car was still starting high on rpms around 1500 - 1600 rpm and then slowly worked it's way back down to 8- 1k. don't know if this is apart of the issue but am just including it just incase.

Last thur/fri the car starts to have fluctuating rpm on a fresh start. What I mean is a start where the car has been sitting for some time with ample time to cool down.

The rpms start out at 15 -1600, settle down and then it starts fluctuating all over the place, at times even sounding like it's going to choke out but doesn't and it shoots up to about 1200.

Well today i got home from work and engine just cuts out as I am pulling in. I park the car shut it off and it starts back up just fine. A little fluctuation but nothing much.

Haven't tried to drive it since this has happened yet.

Any help would be appreciated.

[Shrak]

Little update.

I went to go take on a short trip around the block it took a couple of times to get the car to start but it started. I stopped, went slow, went fast a couple different times and nothing happened, no rough idle or anything like that.

It's not even throwing a check engine light.

[Eg.h2o]

Check the rubber snorkel hose from the airbox to the throttle body. Remove it from the engine and check it completely for splits and cracks. If any are found, replace it, duct tape is not the answer.

[Shrak]

The air intake house should be fine, I just replaced it sometime earlier this year.

I will check it again just to make sure, there shouldn't be any issues with it though.

If you are referring to a different line, all I have is the in take and a coolant line that runs through the throttle body, that is it though.

I got a few videos of it happening I will try to get them posted to the thread.

[Shrak]

Here are a couple of videos of what is going on.

The first on is from this morning before heading into work.

https://youtube.com/shorts/o0Qvx9v30...D3WhERZ2Ql5tIM

The second one is from last night after the stall and giving the engine time to cool off.

https://youtube.com/shorts/o0Qvx9v30...l-np0pdwMEHXM6

The one thing that has changed now is that it is now doing it after a while in parked idle not just when starting up from a cool/cold engine.

[johanbrandon]

It seems like you've already taken a step by replacing the electronic throttle body, addressing the previous stalling issue. However, the fluctuating RPM and the recent engine cut-out indicate there may still be underlying issues.

1. [COLOR=var(--tw-prose-bold)]Idle Air Control (IAC) Valve:[/COLOR] Even though your car has an electronic throttle body, it might have an integrated IAC function. Check for any clogs or malfunctions in the IAC valve that could be causing the erratic idle.
   
2. [COLOR=var(--tw-prose-bold)]Vacuum Leaks:[/COLOR] Inspect for vacuum leaks in the intake system, as they can lead to inconsistent idle and stalling. Check hoses, gaskets, and connections for any signs of wear or damage.
   
3. [COLOR=var(--tw-prose-bold)]Throttle Position Sensor (TPS):[/COLOR] Even with the new throttle body, the TPS could still be a culprit. Ensure it's properly calibrated and functioning to maintain stable RPM.
   
4. [COLOR=var(--tw-prose-bold)]Mass Airflow Sensor (MAF):[/COLOR] A faulty MAF sensor can contribute to irregular idling. Clean or replace it if necessary.
   
5. [COLOR=var(--tw-prose-bold)]Fuel System:[/COLOR] Check the fuel system for issues such as a clogged fuel filter or a failing fuel pump, as they can affect engine performance.
   
6. [COLOR=var(--tw-prose-bold)]Engine Control Module (ECM):[/COLOR] A malfunctioning ECM could lead to various issues. Consider having it checked or reprogrammed if needed.

If problems persist, it's advisable to consult a professional mechanic or use diagnostic tools to pinpoint the exact cause. Addressing these potential issues should help stabilize your car's idle and prevent stalling.

[JamesBurke]

If the downstream cat is plugged, your Aveo will start and run for a few minutes and then quit. Replace or drill the cat and it will run OK. (the other suggestions here are useful, too)

[northguest47]

Heya this thread is a similar situation to mine. I'm cleaning out the throttle body, and just learned about the accelerator switch, so it could be a plugged cat too? Is there any way to test for this my car was misfiring for a few months and that concerned me about sending unspent fuel into the exhaust.

Curious if Shrak found out the issue too.