2008 Hummer H3 Run Perfect Cold, but Stalling at Warm Idle....Exhaust Cam Phaser?
 

I have a 2008 Hummer H3 with about 150k miles. The H3 is now “Stalling” after having the Cylinder Head Repaired. The job included a new Timing, crank sensor, cam sensor, MAF, MAP, and VVT Oil Control Solenoid. On a Cold Start Up, the vehicle runs perfect with no stalling issues. After “Warm Up” as the Electronic Throttle Closes, the vehicle stalls in any gear (including Park or Neutral. On a warm engine, if I use the accelerator to control the idle speed at 900 RPM, the H3 will not stall. I have code 0017 (cam / crank correlation).

I have reopened the engine to look at the timing and the timing marks appear to be correct. I think all is ok there.

I am slightly concerned about the exhaust cam phaser which is original to the H3. I don’t know much about phasers. When at rest with the engine off, the cam sprockets are perfectly timed, but the exhaust cam flat is not horizontal to the head, therefore the exhaust phaser is not either. The exhaust cam flat and the exhaust phaser are connected and facing maybe 11:00 instead of horizontal to the head at 12:00. I can rotate the exhaust cam phaser with my hand maybe 1”+ clockwise to get it to face 12:00. I have provided pictures below.
https://cimg2.ibsrv.net/gimg/www.hum...d4e622162a.jpg
https://cimg3.ibsrv.net/gimg/www.hum...dabbbaba5f.jpg
https://cimg5.ibsrv.net/gimg/www.hum...ea914a2c15.jpg
https://cimg6.ibsrv.net/gimg/www.hum...ae1a48c77f.jpg


I need to give an example of what my engine is doing.
*Let’s assume then the engine is off and #1 is TDC.
*At that point, the flat on the rear of the intake camshaft is horizontal to the head.
*The flat and the phaser on the exhaust camshaft are connected on opposite ends of the exhaust camshaft and facing 11:00, not 12:00.
*At rest with engine off, should the exhaust camshaft phaser be in a fully advanced state (meaning facing 12:00) OR is a slight tilt to the left, facing 11:00 ok?
*My exhaust phaser is facing 11:00 at rest
*Does that mean that my phaser is bad and needs to be replaced?

I have seen many posts on different forums with the exact same issues, but I have yet to see a diagnosis. Thanks for taking the time to read and potentially help!

Who did the head work? Ask them why their work has this issue.

IMHO might have an open loop to closed loop problem. During warm up the open loop sets the parameters. Once the PCM switched to closed, something is not getting the correct feedback. Scan it if you have not already and provide the entry to closed loop data.

When was the last time the Throttle Body was cleaned with TB cleaner? If that is sticking............ I'd be looking there.

And let it idle 5+ minutes to re-calibrate after the cleaning.

I scanned the entire system today. After the PCM goes to closed, the motor will not idle without manually pressing the accelerator. There is only 0017 code.

Also, the throttle body was cleaned recently. We should be good there.

when in closed loop the pcm relies on maf, o2's and engine temp data to function. check the readings.

I was able to capture some live data this morning. I have a blue BlueDriver, so my screens shots are limited. I can collect other data upon request, but this is what I had trending this morning.

All charts appeared to be stable until the H3 warmed up. I am sure there are other components fluctuating, but the largest deviations appeared to be with the O2 Bank 1- Sensor 1. Take a look and please let me know if you have any suggestions. Again, I can gather other information. Thanks.
https://cimg4.ibsrv.net/gimg/www.hum...906cddae17.png

O2 1-1 and 1-2 seem to be reading the same value. usually the means the cat is not reducing emmissions maybe needs the monitor set with some drive cycles ? idk.
your absolute throttle posision also seems a bit high as if the pedel is being depressed by 22 percent. maybe dirty or obstructed throttle body ?
the MAF also seemes high but maybe because throttle position?

Who/how was the Throttle Body cleaned "recently" and what is recent? What was used to clean it?

Your TB is inconsistent relative vs absolute as bronxteck noted. When one uses the wrong cleaner and does it in place, it can make its response worse instead of better.

I am sorry. The data I posted is with the accelerator press slightly to keep the H3 running since it was warm and wanting to stall.

Below, I have posted new data with the car warm without touching the accelerator. Sometimes it will stay on after it is warm, but tends to oscillate on the rpm and run rough. When it does stay on and run rough, I can press the accelerator and release it to return the engine back to idle....it almost immediately shuts off. I can crank again with a slight press of the accelerator, but it will shut down or not crank at all when accelerator is released.

As far as the throttle body, it was removed from the engine and cleaned with actual throttle body cleaner.

Let me know if I can provide any additional info. Thanks for the help on this.
https://cimg6.ibsrv.net/gimg/www.hum...1657ad0bf5.png
No accelerator pressed
https://cimg7.ibsrv.net/gimg/www.hum...7e23091dac.png
No accelerator pressed

have you checked exhaust backpressure? maybe the cat got damaged during reinstal and plugs up when hot?