Hummer H3 For the Hummer driver who wants the rugged look and off road capabilities of the Hummer, but in a smaller size and with a more fuel economy friendly engine.

H3 stalling in driveway- need some help

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  #1  
Old 10-12-2019, 01:33 PM
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Default H3 stalling in driveway- need some help

I'm at a loss right now, I'm not sure where to proceed

Problem:When the truck is up to temp it idles rough and then stalls at stop signs and red lights
If I start it cold in the driveway and let it sit until full temp, Once at full temp it will start to idle rough and then stall,
After stalling it restarts immediately, but will stall within a minute or two.
No codes thrown- no check engine light
Seems to drive fine once i give her some gas i have no power loss

Corrective actions so far
New to me 06 H3 150,000 miles.
Vin 3026XX ( i believe out of the valve danger zone)
Cleaned MAF
Cleaned resonator box
Cleaned throttle body
Replaced airfilter
Replaced bad breather hose under resonator box
New ACdelco MAP
New ACdelco Sparkplugs
New ACdelco O2 sensors
New Acdelco MAF ( replaced 10-14-19)
New Acdelco camshaft actuator solenoid valve
New Acdelco Cam position sensors
New battery
Inspecting wire harnesses for damage ( ongoing )
Looked for a vacuum leak unable to find one so far
Checked gas cap for tank vacuum
Intake manifold seems tight
Full tank of new gas

Any help would be greatly appreciated I'm really stuck right now
Thank you
Steve
 

Last edited by H3steve; 10-14-2019 at 09:42 PM.
  #2  
Old 10-12-2019, 02:44 PM
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Did you clean the coils contacts?

crc electronic cleaner/dielectric grease

Did you clean the injectors?

 
  #3  
Old 10-12-2019, 02:54 PM
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Also, try disconnecting the maf sensor at operating temperature, turn ignition off, then start and let idle.
 
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Old 10-12-2019, 03:13 PM
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Originally Posted by hummerz
Did you clean the coils contacts?

crc electronic cleaner/dielectric grease

Did you clean the injectors?

https://www.youtube.com/watch?v=O5N_Z1W6mho
Coil contact seemed very clean and spark plug wells that they sit in. But I didn't clean them.
I can do this.

I agree that injector cleaning is a good idea. I plan to do that, I am confused why a dirty injector would only be affecting the truck when hot? Not busting your ***** I'm looking for a teachable moment.

Thank you



I appreciate all your help
 

Last edited by H3steve; 10-12-2019 at 03:19 PM.
  #5  
Old 10-12-2019, 03:17 PM
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Originally Posted by hummerz
Also, try disconnecting the maf sensor at operating temperature, turn ignition off, then start and let idle.
This is new to me can you please explain what's happening when this process happens.

Just to be clear you want me to:
Start truck and idle to full temp
unplug the maf while the truck is running
Observe the results for a time
Turn off the truck
Start the truck
Observe the results for a time
Turn off the truck
Reconnect maf
Restart truck
Observe the results for a time


I really appreciate your help
 
  #6  
Old 10-12-2019, 04:24 PM
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try monitoring your fuel pressure if possible when it is running normal and when it is running bad and see if there is a difference. fuel pump could be acting up when hot.
another test is when running bad open the fuel tank cap if it gets better and normalizes then maybe you have a stuck purge valve or gas cap that is creating too much vacuum in the fuel tank restricting fuel flow.
are you loosing any coolant from the coolant tank and you cant find any leaks then it could be blowing out the tail pipe usually a white smoke... head gasket or cracked engine head or block.
 
  #7  
Old 10-12-2019, 07:26 PM
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Originally Posted by H3steve
This is new to me can you please explain what's happening when this process happens.

Just to be clear you want me to:
Start truck and idle to full temp
unplug the maf while the truck is running
Observe the results for a time
Turn off the truck
Start the truck
Observe the results for a time
Turn off the truck
Reconnect maf
Restart truck
Observe the results for a time


I really appreciate your help
Originally Posted by H3steve
I'm at a loss right now, I'm not sure where to proceed

Problem:When the truck is up to temp it idles rough and then stalls at stop signs and red lights
If I start it cold in the driveway and let it sit until full temp, Once at full temp it will start to idle rough and then stall,(turn ignition off, disconnect maf sensor, restart and observe)
After stalling it restarts immediately, but will stall within a minute or two.
After stall, turn ignition off, disconnect maf sensor, restart and observe.
 
  #8  
Old 10-12-2019, 07:41 PM
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Originally Posted by H3steve
Coil contact seemed very clean and spark plug wells that they sit in. But I didn't clean them.
I can do this.

I agree that injector cleaning is a good idea. I plan to do that, I am confused why a dirty injector would only be affecting the truck when hot? Not busting your ***** I'm looking for a teachable moment.

Thank you



I appreciate all your help
Sorry, I'm not a teacher, just offering advise on past successful repair experiences. However, you can find many sources to learn the temp effects on resistance.
 
  #9  
Old 10-12-2019, 08:06 PM
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Originally Posted by hummerz
After stall, turn ignition off, disconnect maf sensor, restart and observe.
So I did this, the idle did not seem to change unplugged or plugged in.
It didn't die while unplugged
I did get a traction fail warning after unplugging it not sure what that's about.

What are your thoughts?

Thank you
 
  #10  
Old 10-13-2019, 01:05 AM
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did you try opening the gas cap when it running rough?
 


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