Hey guys im stuck and about to go to the dealership. I am aware of the soft valve seats not sure that that is my problem . This code just suddenly came on.

06 H3
150,000 miles
Vin # last six 320XXX ( out of danger zone i believe)
New VVT solenoid, MAP, MAF , new Injectors, cleaned throttle body, Check PCV hose, intake bolts are tight.
Compression tested each cylinder all at 180 psi
Checked fuel pressure at Schrader valve on rail I had a constant 58 PSI

1. My buddy came over with his scanner tool we observed the truck starting fine in the driveway the engine is cold at this point.
2.We let it sit at idle parked watching it reach full temp 200F.
3.it abruptly shuts off once at full temp
4. we can restart it immediately and all cylinders are misfiring all over the place and we are unable to keep it at idle without giving it gas, We are now getting P0300 codes as we should with all the misfiring.

Any one have any other thoughts that the header and valves, i would love to hear it please.

 

check your fuel pressure when that happens. 54 psi she's happy less then that check your fuel delivery system

 

Not sure but I did read something about camshaft actuator solenoid issue. Might be worth a shot.

 

I checked that at the rail Schrader valve I have 58 psi. I will add this to the OP

Thank you for getting back to me

 

but did you watch it when the issue happened for dips in pressure sometimes when fuel pumps are hot they fail let them cool off and they act fine restricted fuel filters / fuel hoses can cause this.

 

Ah! Thank you for asking in another way.

I watched the gage for 2 minutes up to the stall and 30 seconds after. I never saw the needle move while at idle or during the stall. I did loose 4 psi a few seconds after the engine was off.

I will admit that I know next to nothing about troubleshooting fuel pumps so any suggestions are appreciated

Steve

 

You have the money to throw parts at it, yet no money for a scanner?

Did you check the fuel trims with your "buddy's" scanner?

Did you test battery charging voltage?

Did you check the wiring and clean the connections to the ckp, cmp, sai sensors?

Diagnose, before you throw more money at it!

Btw, your fp checks out good.

 

A hot crank shaft sensor will do this. Also, there are multiple other wiring and sensors that could be faulty. Your compression is good. I'd look into this ....

https://www.hummerforums.com/forum/h...m-07-h3-42118/

Might help to..
Live stream data.

 

yes a faulty when hot crank position and or cam position sensor can also cause stalling. you would have to watch the signals with a good scanner or scope.