If the discussion was all in one thread it would make some sense to future readers.

 

I’ll see what I can get done , when I’m back home in Wifi.

 

How did you reset the Fuel Trim and Alcohol content? I'm having the exact same symptoms in my wife's HHR. Already replaced both O2 sensors, Air Filter, EVAP Purge Valve, MAF sensor, and cleared the codes. Also ran some Fuel injector cleaner in the tank. Seems to be running better but the CEL keeps coming back on with the P0172 Code and has a heck of a time starting in the mornings.

 

Did you check for cracks in the air horn and the OCV hose and any other source of unmetered air?

 

I did check all the vacuum hoses I could find, and didn't see any signs of cracks or air leakage. What did you mean by the "Air horn"

 

The rubber tube from the air cleaner to the throttle body and the rubber hose from the valve cover to it.
And make sure it is tightly clamped to the throttle body.

Any air leak between the MAF and the #1 O2 sensor can cause trouble.

 

I had that exact problem with my daughter's 2011 HHR a few months ago. I took it to a local garage that I trust, they reset the stored alcohol %, and all is well now.

Steve

 

Awesome, thanks for the follow up!

 

Perhaps repeating, clearing codes does NOT reset the ethanol %. You don't need to reset the fuel trim, just the ethanol %. Maybe. Have you verified that it's erroneous? Some low-cost scanners can read it. Free parts store can't scans. Can usually do it, but their people may have trouble finding it buried in the menu structure. It's not just a code. It takes a fairly capable scanner to reset it. My local Chevy dealer just charged me $65 to reset it, but he didn't have to do any diagnosis, simply complied with my request to set the stored ethanol content to zero.

In the meantime, hold the pedal to the floor after the first crank or two, thereby placing it in flood clearing mode, i.e., zero fuel.

 

I did check the rubber tube from the throttle body and that rubber hose. No visible air leaks or cracks I could see or feel. Thanks for the suggestions!