6.2 Hesitation

[Eric De Carteret]

Hey guys,

I've got an 09 Yukon Denali that seems to have a slight hesitation/putter every once in a while when leaving a stop sign or a slow roll from idle. It almost feels like there might be a brief misfire but no codes are thrown. Engine temperature doesn't seem to be a factor since it sometimes happens once everything is up to temp. At any other time it seems to run like a champ!

The truck has always had the Costco Brand Top Tier premium fuel in it since I have had it. The plugs and wires were both replaced with delco parts within the last 1,000 miles so I don't expect that to be an issue. Also, I grew up in a house where Techron was used religiously so I don't anticipate gummed up injectors either. Bought it with 100,000 and it now has 118,000.

Planning on checking fuel pressure soon to see if its the start of a bad sending unit.

Anyone else have a similar experience with a fix?

 

[OR VietVet]

If has not been done I would recommend starting with easy basics first. Get a Mass Air Flow Sensor cleaning kit at the parts store and follow the directions to the letter and open up the access and clean the throttle plate for the throttle body. The fuel pressure check is also recommended.

You said "but now codes are thrown". Did you mean to say NO codes or NOW codes are thrown but if so I want to know what codes you retrieved.

 

[Eric De Carteret]

If has not been done I would recommend starting with easy basics first. Get a Mass Air Flow Sensor cleaning kit at the parts store and follow the directions to the letter and open up the access and clean the throttle plate for the throttle body. The fuel pressure check is also recommended.

You said "but now codes are thrown". Did you mean to say NO codes or NOW codes are thrown but if so I want to know what codes you retrieved.

I think I might actually have a MAF cleaning kit in the garage. Going to give it a shot.

NO codes are thrown unfortunately. Sorry for the typo..

 

[OR VietVet]

Make sure to check air filter and replace as needed. If you can get a long hose on the fuel pressure gauge and tape the dial to the windshield and drive it and see what that pressure is doing when driving. Besides the plugs and wires have you done any recent work or had any recent codes?

 

[Eric De Carteret]

Make sure to check air filter and replace as needed. If you can get a long hose on the fuel pressure gauge and tape the dial to the windshield and drive it and see what that pressure is doing when driving. Besides the plugs and wires have you done any recent work or had any recent codes?

The air filter was replaced with a Wix upon receiving the truck. Took out a like new delco filter.
I did put on a new alternator a few months back solving a persistent "service battery charging system" display. The only other thing that happens from time to time is that the service traction control/stabilitrak/abs lights come on when stopping at a light or something. Those lights go out once the truck is restarted after sitting for a few minuets. I suspect a wheel speed sensor for that but haven't had a chance to meet up with my friend who has access to a tech 2. Other than that its just general maintenance/fluids as needed.

 

[OR VietVet]

We keep hearing about the throttle plate clean and clean the MAF fixing slight hesitations here.

 

[Eric De Carteret]

We keep hearing about the throttle plate clean and clean the MAF fixing slight hesitations here.

Thanks, I'll check it out!

 

[01FormulaTA]

clean the throttle body

 

[swathdiver]

Hey guys,

I've got an 09 Yukon Denali that seems to have a slight hesitation/putter every once in a while when leaving a stop sign or a slow roll from idle. It almost feels like there might be a brief misfire but no codes are thrown. Engine temperature doesn't seem to be a factor since it sometimes happens once everything is up to temp. At any other time it seems to run like a champ!

The truck has always had the Costco Brand Top Tier premium fuel in it since I have had it. The plugs and wires were both replaced with delco parts within the last 1,000 miles so I don't expect that to be an issue. Also, I grew up in a house where Techron was used religiously so I don't anticipate gummed up injectors either. Bought it with 100,000 and it now has 118,000.

Planning on checking fuel pressure soon to see if its the start of a bad sending unit.

Anyone else have a similar experience with a fix?

Eric, you've got a Vette and a Denali, get your own Tech-2. Run a graph of your O2 sensors and watch your fuel trims and see if anything is amiss there. Use the Tech-2 to check everything, including those chassis codes.

You can run tests on VVT acuator, injectors, coils, etc. Do it all but carefully. Sometimes a faulty purge/vent valve can cause this too. The Tech-2 can test for that too.

 

[Eric De Carteret]

Eric, you've got a Vette and a Denali, get your own Tech-2. Run a graph of your O2 sensors and watch your fuel trims and see if anything is amiss there. Use the Tech-2 to check everything, including those chassis codes.

You can run tests on VVT acuator, injectors, coils, etc. Do it all but carefully. Sometimes a faulty purge/vent valve can cause this too. The Tech-2 can test for that too.

Yeah, a tech 2 should be on my list for sure. It was nice when my old man was still working as an engineer at the proving grounds and had easy access to all the tools I'd never have to buy..