2007 Yukon Delali 6.2liter will start but will not run

[TraumaTruck1]

I have a 6.2 Liter Denali that will start, but it will not run unless I hold the gas down. Holding the gas down will keep it running, but it has a severe miss.

It was running perfectly. My wife and I had been in it all morning with no problems. We stopped at a store, got back in it, it started running rough, and then went dead as I was trying to back out of the parking space. It will start every time, but I have to hold the gas down to keep it running. It runs really rough with a severe miss and knock.

I am at a loss. There was no warning, and it is not turning any lights on.

 

[08grey]

Could be a leaky injector flooding a cylinder. Could be a bad maf sensor. It's likely flooding and running rich. Check all your plug and injector connections to be safe first. Could be as simple as a field mouse chomped on a wire.

 

[biggreen04]

Could be a leaky injector flooding a cylinder. Could be a bad maf sensor. It's likely flooding and running rich. Check all your plug and injector connections to be safe first. Could be as simple as a field mouse chomped on a wire.

Sounds like a throttle body issue

 

[08grey]

Remove the negative cable and let it sit a while and reset and reconnect.

 

[02Burgundybeast]

Any solution to the problem?

 

[TraumaTruck1]

Sorry for the Delay in response. I have been really busy with work.


I took it to a mechanic that I know since I didn't have time to work on it.

He started it, and it was running codes for cylinder 5 and 7 missing and would barely run while holding down the gas. They did a compression test on those 2 cylinders. One of them had no compression, and the other one was fine. Took the valve cover off, and the cylinder with no compression had a broken valve spring and bent push rod. He had no explanation for why it happened, and he said that he couldn't see anything that scared him about it. Everything was clean and looked new.

Running well now.