Stalls at low idle when hot and wont restart

[xdieselmechanic]

I apologize for long post put going to try to explain everything.
Parts replaced so far:
Cam sensor
Crank sensor
Cam phaser valve
Cam phaser solenoid
Fuel pump
Maf
1 injector
Pcm
Pdm

So about 2 weeks ago coming off the highway my 2007 yukon xl with the 6.2 stalled and would restart. Had unit towed back to house and I messed around with relays and unit started. Drove it the next day and same thing. Had it towed again. Scanned unit and had code p0300 with misfire data showing mainly cylinder 7 but I know that won't cause a no start. Measure fuel pressure and found only 42 psi replaced pump to have unit stall again and not restart. This time I stayed on back roads and just waited for it to restart about 30 to 60 min. During this time I found I have no injector pulse but have good power at injectors. Started unplugging 1 injector at a time and found when unplugging cylinder 7 pulse came back so i changed injecto and same issue. Turns out unit just happen to ready to start at that time. Scanned into unit and found no reason for the pcm to take away injector pulse so I replaced the pcm and same issue. I figured timing sesnor controlled the injector pulse so I replaced both sensors and while I had the water pump of i replaced the vvt components while i was in there. Read multiple people have luck chaging the maf for this issue so I changed it. Unit still stalls to this day and loses injector pulse on the ground side when it does. Have noticed watching the live data the pcm is request injectors to fire via injector pwm value. I have redone the ground wires at the left bottom of the block knowing this was the ground location for the pcm but still no luck. I am a mechanic by trade but this is having me pull my hair out. If anyone has something to have me check I will gladly im not much of a parts thrower but im about to load the cannon

 

[Fless]

So about 2 weeks ago coming off the highway my 2007 yukon xl with the 6.2 stalled and would restart.

Do you mean "wouldn't?"

Does the engine crank, but not start?

What brand parts are being used? Looks like quite a few have been changed already.

Throttle body been cleaned lately?

Can you monitor the engine coolant temp when it won't start?

 

[xdieselmechanic]

Do you mean "wouldn't?"

Does the engine crank, but not start?

What brand parts are being used? Looks like quite a few have been changed already.

Throttle body been cleaned lately?

Can you monitor the engine coolant temp when it won't start?

Crank no start condition oem parts and temp reading good

 

[xdieselmechanic]

Crank no start condition oem parts and temp reading good

Sorry I also clean tb

 

[rdezs]

Check the purge valve on the intake manifold that it's not stuck open. (Which can flood the intake with fuel vapor and cause stalling)

Clean and check all your grounds.... Check resistance on both battery cables.

After replacing the crank and cam position sensors, did you perform a relearn?

One more thought. Verify with live data on a scanner that the engine coolant sensor is reporting accurately.... And wiggle the harness connector around to see if that changes the readings. It's close to the exhaust manifold, eventually gets damaged from the heat.

Hopefully you have a scanner that will record data as you drive.... Then after it stalls you can review exactly what was happening.

 

[xdieselmechanic]

Check the purge valve on the intake manifold that it's not stuck open. (Which can flood the intake with fuel vapor and cause stalling)

Clean and check all your grounds.... Check resistance on both battery cables.

After replacing the crank and cam position sensors, did you perform a relearn?

One more thought. Verify with live data on a scanner that the engine coolant sensor is reporting accurately.... And wiggle the harness connector around to see if that changes the readings. It's close to the exhaust manifold, eventually gets damaged from the heat.

Hopefully you have a scanner that will record data as you drive.... Then after it stalls you can review exactly what was happening.

I have done all this already from what I can tell i loose nothing from live data when it stalls but what I loose is the inkector pulse even though pcm is commanding it on

 

[rdezs]

You'll probably have to check your harness closely, all the way from the ECM to the injectors. It's not uncommon for heat to affect a weak electrical connection.

 

[LsHart]

I would move relays around and see if problem is still there. Something is getting hot and cooling down. Relays have been in there for a long time.