I've got an appointment tomorrow on my lunch break to take it to a local shop who's going to try and reset the stored alcohol %. Hoping this will be my "Fix" They said they'll do it for free if it just takes a few mins, otherwise maybe $50 tops. Still cheaper than me buying a scan tool and doing this myself. Thanks for the suggestion!

 

Thank you for the suggestions. I'm going to try and have a local mechanic reset the ethanol % tomorrow

 

Well.... I brought it to a local shop to reset the alcohol %. Result was now it's running 10x worse. Used to just have rough starts and clunky idle. Now I can't even drive it, in drive at a stop light the car dies. Stepping on the accelerator sometimes has NO power, and it's now emitting a strong smell. In addition to all of this I've got a new ESC light and "Check ESC" warning that was never there before... Man do I regret this and wish I could go back to how it was before, at least the car was still drivable. Now it's just a lawn ornament...

 

To repeat my prior question, did you verify that it was erroneous before you reset the ethanol percent? The way you do that is to test a sample of fuel from the tank and compare it to the stored value. if you didn’t sample, do you at least know what the stored value was? if there’s 50% ethanol in the tank, for example, zeroing the value will leave it very lean in open loop, and it won’t correct itself until it goes into close loop, when tit should run better but will likely set a P0071.

How much fuel is in the tank? Is it low enough that you could add about 5 gallons? That will prompt the ECU to reevaluate the stored ethanol value.

This issue has been commented upon several times in detail. There’s a bit of chaff the hundreds of comments in this thread, but It’s best to really understand what’s going on before you take action.

 

Sorry I must have missed your prior mention. No unfortunately I did not test a sample prior to the reset and I don't know what the stored value was as I didn't do the reset myself, it was done by a mechanic at our local shop. No, I don't think I can fit 5 gallons currently. I recently filled the tank when added some fuel injector cleaner when I first started trying to diagnose the issue. I can maybe siphon some fuel out in order to accomplish the ECU reevaluation like you mention. I know, it's a pretty long thread and I did my best to read all 22 pages but might have missed some. I apologize if I'm asking questions that have been addressed already.

 

An update.
I bought a bi-directional GM Scan tool made by Launch. Did the Resets for Fuel Alcohol % and cleared the codes. Viola, problem gone. Apparently the shop I brought it to didn't reset the correct parameters either by mistake, or on purpose. Whatever it was they basically disabled the car causing misfire and many other issues. TSC light came on? Weird and definitely brought up some "Trust" issues...
All that aside, problem is now gone, no more rough idle and difficulty with cold starts.

 

What model Launch scan tool did you get?

I find some shops just don’t know what they are doing and can’t be bothered to read the directions!
Glad you got it fixed and running fine!

 

The codes caused the Traction Control to turn off. I would not celebrate until all of the OBD tests are "ready".
Read directions? I don't understand what that could mean. Manly men don't need no f'n directions!

 

I find them important in some circumstances.