New problem with this 2012 Yukon XL 1500 Denali 6.2L. I really hate this truck! GREMLIN is back

[greg vess]

Vacuum bump.....But I agree with the rest

I would have fuel injection but that's it..The self learning systems are plug and play..

Are you talking about a vacuum canister to hold vacuum on reserve? If the camshaft isn't to big there should be no need. The IAC ( idle air control valve ) with fuel injection takes care of that. If the computer reads a sudden decrease in RPM's the little plunger opens and closes to let air bypass the throttle blade and keep idle stable under a load . These new self learning fuel injection systems take care of all that for you.

On the plus side there is no sloshing of fuel back and forth and side to side in the gas tank and float bowls of a carb. That can cause a lean spikes in the AFR or total starvation. It's the ultimate air fuel delivery system .

 

[basstracker89]

I would have fuel injection but that's it..The self learning systems are plug and play..

Are you talking about a vacuum canister to hold vacuum on reserve? If the camshaft isn't to big there should be no need. The IAC ( idle air control valve ) with fuel injection takes care of that. If the computer reads a sudden decrease in RPM's the little plunger opens and closes to let air bypass the throttle blade and keep idle stable under a load . These new self learning fuel injection systems take care of all that for you.

On the plus side there is no sloshing of fuel back and forth and side to side in the gas tank and float bowls of a carb. That can cause a lean spikes in the AFR or total starvation. It's the ultimate air fuel delivery system .

Yes on Vacuum. Until you have problems on the computer on the other. The old Ford was right as rain till the rodents got it

 

[sniper22]

Gremlin lives!

BTW when I drove to see my mechanic friend at the GM dealer he showed me one of 4 vehicles he is attempting to repair. A brand new 2026 Chevy Equinox with 177 miles. Owner was driving home on interstate when it just died. It was towed to him and he says it has a completely dead battery and no fuel pressure. A new battery and new fuel pump were installed and it ran for 15 minutes and died again with same results. He doesn't have time to kill my gremlin he has gremlins of his own. LOL

Having not read this entire post, I would change the temperature sensor and wires to it. Ive had late 80s models up to 2015 GM vehicles that would do all kinds of crazy stuff from a bad sensor. The Chinese sensors will work most of the time but they actually create a slight ground issue that is hard to find without using a scope.

 

[prestige30165]

Fuel pressure of 43 (Should be 55-60) is low for an LS, I would change the fuel filter and see if that helps on the pressure

 

[testdepth]

I drove it this morning and was able to get a video of what it is doing but I pushed through it and it settled out with no further problems. Just the once. The engine was at about 170F and normal is 210F. At 14 seconds it starts at about 25 mph. If you turn up the audio you can hear the engine surging and see the tach bounce up and down.

When this happened to my wife yesterday she immediately pulled over and then the engine died I assume because when she pulled over the rpm dropped to low to recover.

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[testdepth]

Having not read this entire post, I would change the temperature sensor and wires to it. Ive had late 80s models up to 2015 GM vehicles that would do all kinds of crazy stuff from a bad sensor. The Chinese sensors will work most of the time but they actually create a slight ground issue that is hard to find without using a scope.

I installed a brand new coolant temperature sensor before last week but it didn't help. Thanks though

 

[testdepth]

Fuel pressure of 43 (Should be 55-60) is low for an LS, I would change the fuel filter and see if that helps on the pressure

The only fuel filter on this truck is attached to the fuel pump and I have to drop the tank to get to it. The new pump is less than 2 months old and a OEM AC Delco.

 

[testdepth]

My scanner shows
Commanded Fuel Pressure is 43.5psi, This shows as a constant value of 43.5psi
Fuel Pressure Sensor shows pressure while driving ranging from 42psi to 45psi.

I'm currently waiting for a kit arriving tomorrow to test the pressure at the fuel rail.

 

[sniper22]

My scanner shows
Commanded Fuel Pressure is 43.5psi, This shows as a constant value of 43.5psi
Fuel Pressure Sensor shows pressure while driving ranging from 42psi to 45psi.

I'm currently waiting for a kit arriving tomorrow to test the pressure at the fuel rail.

What scanner do you have /use ?

 

[testdepth]

What scanner do you have /use ?

TOPDON ArtiDiag900
TOPDON TOPSCAN

They are good scanners but missing the one feature all scanners should have. Just one function that when you plug it in it tells you exactly what's wrong and needs to be changed to fix the problem. But NOOOOO we have to test all kinds of **** and interpret what may be wrong. Reminds me of equipment in the military where the troubleshooting procedure was to replace one circuit card at a time until your problem went away.