Watch this video may help.
In any event I believe you need to get a scanner hooked up and watch whats going on.

 

Granted it's not an HHR but it is a GM Ecotec Flex fuel auto.

 

I just watched another one of his that pushed me even further to look further.

 

He has some very good videos. I've seen a couple of other instances where the calculated alcohol content wasn't correct. You will see it in the trims for sure, the key is to find out what it thinks the content is.

 

There are two things I see these videos, looking at fuel trims (short term) and alcohol percentage. In the first video an update to the injector codes will get the fuel trim back into a normal range along with correcting for the gas used..
The second to me it showing a rich condition where again short fuel trim is monitored and again content of alcohol percentage measured.
Not having trim codes or a way to reset fuel (alcohol) is a problem.
Having a good tool can help a lot.
Going to a "smart" dealer is a crapshoot.

 

Got a buddy with a Matco Maxme that I'm borrowing this weekend. Should get me a bit more info.
I wanted to double check the coolant temp sensor readout, and possibly clean the throttle body. I noticed there isn't an IAC like on most other vehicles I'm familiar with, so I'm assumign that's incorporated into the throttle body's electronic control.

 

The Matco will do it. With DBW engines there is no IAC. ECM controlling the opening of the TB does the same thing. You will see the opening voltage/percent of the TPS change when ECM is adjusting idle speed. Cleaning TB would help if the blades were not closing completely, the fact that you are applying gas pedal input points to something else.. I believe.

 

I agree. Let's see what the values come up as.
cturboaddict fill us in.
This is a good one.
No checking grounds or battery lobotomy on this one.

 

Found a couple that suggest cleaning the throttle body.
I might have missed it, have you cleaned it yet ?

 

I have not. But have a new gasket arriving today just in case. It's on the "to do" list for this weekend after getting some scan data.