Better startup with higher ethanol

[KyleSM]

2011 Yukon Denali L94 6.2 Flex Fuel 160k miles...

I had some stumbling on a dead cold start up after filling the tank a while back. Cleaned the throttle body and it ran better for a bit, I think it just brought up the idle till it recalibrated. Then I ran a tank of ethanol free premium and my startup stumbling got worse. Sometimes the engine would even fire over but then die.

I chased down a bunch of potential issues and ruled them out after getting a tech2 emulator. On a hunch, and against all internet advice, I topped off a half tank with E85. The onboard ethanol calculated to 24%.

Now my cold start up issues are gone. After all the research, I'm going to try to get my AFM turned off before I run into valve issue...

Has anyone else run into this kind of thing? Where E85 runs better than ethanol free (aka 100% gas)?

 

[Joseph Garcia]

@swathdiver

 

[swathdiver]

2011 Yukon Denali L94 6.2 Flex Fuel 160k miles...

I had some stumbling on a dead cold start up after filling the tank a while back. Cleaned the throttle body and it ran better for a bit, I think it just brought up the idle till it recalibrated. Then I ran a tank of ethanol free premium and my startup stumbling got worse. Sometimes the engine would even fire over but then die.

I chased down a bunch of potential issues and ruled them out after getting a tech2 emulator. On a hunch, and against all internet advice, I topped off a half tank with E85. The onboard ethanol calculated to 24%.

Now my cold start up issues are gone. After all the research, I'm going to try to get my AFM turned off before I run into valve issue...

Has anyone else run into this kind of thing? Where E85 runs better than ethanol free (aka 100% gas)?

Kyle, your alcohol content and trims might be off and this happens once in a while and needs to be reset with a Tech-2.

To reset the computer, run the tank down to near empty and then refill with E10 fuel. Then using your Tech-2 emulator, do a Fuel Composition Reset and a Fuel Trim Reset. You can also look for a faulty injector by running the Cylinder Power Balance and Fuel Injector Balance. You can also take a look at the fuel pump, check its trims and even command the pump to deliver more fuel if it seems low on output. The Fuel Composition Reset resets the computer to 3% and then once you start driving will begin calculations anew.