2003 Vibe GT with high and surging idle

[canvibe]

I'm running low on things to check regarding this idle surging and very high idle (4250 RPM) when any throttle is applied.

2003 Pontiac Vibe GT.

Here's a video demonstrating the issue:

Initial issues:

• Car was idling high, in the 2200 RPM range.
• Occasionally, while in neutral (manual transmission) the engine would start to rev high, in the 3500 RPM range.
• If revving high, "Punching" the throttle would kick the RPM back down.
• No issues with stalling
• Exhaust smells like the car is not burning clean

Work already complete:

1. Throttle body has been cleaned really well with proper throttle body cleaner. It was pretty dirty. Cleaning actually made the problem much worse.
2. New Idle Air Control Valve. I'm confirmed the new valve is receiving proper power and opening when power is applied.
3. New Mass Air Flow sensor. I'm pretty sure the old sensor was working fine, but I replaced anyways.
4. I cannot find any vacuum leaks, although putting a vacuum gauge on a line shows that the pressure is surging in sync with the idle surging.
5. Currently, no engine error codes, although they were cleared after throttle body clean and idle air controller replacement. I'm using OBD Fusion app.
6. Completed Idle Release steps several times. I can see some minor idle hunting, but idle is high (3000 RPM) on a cold start or computer reset (discharging battery).

6-speed manual transmission.

Here's the OBD codes before any work was started:



Screenshot of gauges while idle surging:



My current guess is the throttle body valve blades(?) are worn or there are gaps, and too much airflow is getting through. I did not check with the back-light test when I had the throttle body removed, but will be investigating next.

Another idea is a damaged intake manifold gasket, but I think that's a long shot.

Any help troubleshooting this crazy issue is very much appreciated. Thanks in advance.

 

[melsg5]

This is a Matrix thread with the same issue

Finally fixed high idle 2003 Toyota Matrix.

I just wanted to share my experience chasing down a high idle in my car. It all started last year after I cleaned my throttle body and IACV. Idle first wouldn't go under 1100, but one more thorough cleaning made it go to 900-1000. The problem was, it would give a P0505 every so often, but I...

bobistheoilguy.com

 

[canvibe]

Update 1:

We found that the intake air cover had one clip that was broken and not holding the cover down completely tight. Put two zip ties on to tighten down the cover, which appears to have solved the idle surging issue.

IACV seems to be working well.

After bringing the engine up to temp, we did another idle relearn process. The engine now idles well, around 850. This seems excellent.

But...

Once again, when we take the car out for a test drive, as soon as you drive away and any throttle is applied and then the clutch is applied, the engine RPM quickly climbs to the 4000 RPM range. It never comes down and the only way to bring it down is to kick the engine to 4500-5000 RPM. Once kicked/punched, the idle drops to approx 1200 RPM. Until you apply even just a little accelerator again, then the engine RPM climbs quickly again to 4000 RPM.

Every single time the accelerator is applied, the engine RPM jumps to about 4000 RPM.

Standing still idle seems perfect. No rough idle. Car exhaust is burning clean.

No error codes.

Here's another video of current state:

Update 2:

Replaced with a new Throttle Position Sensor. Performed an idle relearn again. Didn't make any difference.

I'm once again scratching my head as I'm out of solid ideas.

Possible options:

1. Replace spark plugs
2. Replace coil packs
3. New valve cover gasket
4. New intake manifold gasket

Any ideas on where to investigate would be very much appreciated.

 

[melsg5]

When the engine is racing spraying carb cleaner or similar substances on intake and valve cover gaskets should reveal a leak but the throttle body may be the issue.

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[Bluetoyo]

Hello there i'm having the same issue as you i have replace my pvc hoses and iac valve but i cant get my rpms to go lower than 1000.

 

[melsg5]

Hello there i'm having the same issue as you i have replace my pvc hoses and iac valve but i cant get my rpms to go lower than 1000.

Have you checked for a vacuum leak?
Do you have any codes?

 

[Bluetoyo]

I cheked for vacuum leak found pcv hose split in the pcv and i dont have any codes i already replace my idle control valve and its the same my throttle body its clean and i checked the iacv and looks clean i dont know what else to check

 

[melsg5]

Here's an article on vacuum leaks incase you missed one. Did you check if the IAC is adjustable?

Vacuum Leak: Understanding The Symptoms, Causes, Diagnosis, And Costs

Vacuum leaks are a common issue in vehicle’s systems. When present, they can cause various performance problems and potentially affect the vehicle’s overall functionality.

www.innova.com

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[Bluetoyo]

Welp, i re checked everything, everything checks good, the car started doing it out no where, and when i press the gas pedal, the rpms go up really fast my buddy lend me his snap on scanner there are no codes in the car, and my IAC is adjustable but doesnt move the rpms much.

 

[melsg5]

You can try looking ar Matrix sites for another idea or have a professional look at it.