Congrats on the fix!

Safer to turn the car off (as instructed in the owners manual) when fueling, anyway.

Save up $20 bill, fold it up, and hide it in your wallet so you never need to add less than 4-5 gallons to the tank, thereby ensuring triggering the ethanol detection routine.

My spouse had been driving 1 mile to work and back every day, then the weather got cold, and we had this problem. One GM TSB say fuel can condense and accumulate in the oil. I think maybe a longer trip can suddenly flash the excess fuel and send it through the PCV valve, conceivably causing a/f confusion. That TSM prescribed a ECM reflash but that was for other models. No such fix for HHRs that I’ve heard of.

Now after many short trips I try to make a longer run to flash off condensed fuel and also roast off any accumulated carbon. Good practice anyway. Also, “TopTier” fuel (toptiergas.com) has more additives to reduce carbon deposits and keep injectors cleaner, mostly sold by major brands but not budget brands. Avoids the cost of bottled fuel injector cleaner.

Some will say avoid E85, but it’s good stuff, more power, cleaner running, and avoiding it won’t assure you never have this problem. It needs to be about 25% cheaper to be worth the higher fuel consumption tho.

Consider cleaning your MAF sensor and throttle body to help keep everything working right.

 

If I do use E15 or E85 will it get the car stuck on the higher fuel composition again? I'm thinking about putting the E15 in again but I can't always get to a station that has it. This afternoon, the car starting up a little hesitant again! No where near what it was doing but I feel like I know where this is going. Put my scanner back on after getting to work and the dang long term trim is back up to -19.5 again! and it's steady on there. this is at idle. If I raise rpm's to about 2000 after about a minute it will drop to -7.0 but that's it. Just sits there. No check engine light YET! The car drives great with the exception there is still a slight surge after letting off gas pedal and coast down to about 40 mph but that's the nature of the beast from what i understand.

all suggestions have been exhausted. I already have a new upstream o2, maf, intake manifold and gaskets, air filter, changed oil & filter, all exhaust leaks fixed and flex pipe not leaking, fuel composition reset with probably at least 200 miles put on the car since that reset, battery labotomy yesterday. Maybe haven't driven long enough since the hard reset but I doubt that. The fuel pump is still noisy like I mentioned but it's been that way for a long time. Purge solenoid working like it should and no leaks in vent or fuel lines.

Trying to be proactive about what to check next but at the same time I'm thinking just drive the thing till the CEL comes on again. But i know it's going to. I'm curious to check the long term trim after putting E15 in but want to wait to see what everyone else thinks about going back to the higher alcohols.

What role would a weak battery play on any of this? Noticed on the scanner that voltage with the key off was 12.4 Shouldn't battery be 12.6. I mean a .2 difference isn't that big a deal to me but not sure how the car feels about it.

 

Rats

So now you at least know what's going wrong, if not why.

-20 trim idk but -7 is no big deal.

What brand and grade fuel did you add last? How much?

You're not getting any other codes like misfires?

I think I already mentioned that using E85 is not the cause of this problem, something in the FlexFuel system is, and the problem can happen even if you never pump anything but E10.

Why do you seek out E15?

I am beginning to beleive that contaminated or low-quality fuel fuel can cause this. I would strongly advise you to buy only "Top Tier" participants - Mobile, Arco, Sunoco, etc., the majors except BP. Avoid bargain brands.

Avoid adding small amounts of fuel unless you're quite sure it's the same grade.

Always turn the car off when refueling.

You still need to do whatever you can to make sure the emission system is in good order.

The prior suggestions are still valid, like Oldblue's suggestion to check for an exhaust leak.

Have you ever replaced the O2 sensor by any chance?

Have you cleaned the throttle body?

Are you going to chase down the fuel pump noise?

 

Pulpfriction, no particular reason to using the E15 other than the car seemed to run better on it vs. regular unleaded. Though not much more of a difference but I'd swear the car ran noticeably better. I remember refueling here at my work place which has ethanol free gas but that was weeks ago and I only put like 5 gallons in because they have it marked ridiculously high in price ($4.74 per gallon). I was not filling up with that price. I needed the gas in a pinch. But this took weeks to ensue.

I overhauled the transmission in the car and was plagued with P0113 for weeks. That's when i decided to buy a scanner. Discovered that for some reason whenever I put the car into gear the IAT sensor would stop communicating. Replaced maf sensor and still had same problem. Unplugged the transmission at main harness and also the neutral safety switch. cleaned those connections and plugged back in and now the IAT sensor/maf communicate fine. Not really sure how those connections are even related or what but it works now.

as for top tier gas, I got none of those around me. I live in Lancaster Pa. Don't know if you've ever been here but it's Sheetz on every stinkin corner or Wawa or Turkey Hill. There was a Sunoco up the street but it was bought out by Liberty. Been using the big chain stuff for 13 years in the car and it never did this. First time for everything! I had exhaust leaks and fixed them but nothing before the cats. Upstream O2 was replaced. Throttle body cleaned. I am replacing the fuel pump this weekend. Finally decided to just use the credit card to get a pump and bite this one. I'd rather do it now before it gets really cold outside!

I decided to buy a bit of a better scanner than the one I had. The one I got now does check fuel composition too. This scanner performs a diagnostic check on the whole car and came back with a C0561-71. The other scanner I had never showed this. Maybe because it didn't look at ABS codes, I don't know. I did change the vacuum hose from the brake booster to the intake manifold. It says online C0561 usually is set from another module. Anyways long story short, I cleared that code and then the car chimed like 3 or 4 times like it acknowledged something and on the display it said something like "service traction" or something of that nature. I'm sorry I can't remember. I ran another scan and everything was green and good to go.

Can a vehicle act up from a stored or history code? The C0561 had originally popped up when the P0113 started haunting me. I fixed the IAT temp thing and I cleared codes with my old scanner but it never brought the C0561 up like this new scanner did. The car has never chimed before either when clearing a code. Why did it chime?

 

I'm no expert but I think ESC can be disabled when there's an engine problem, hence the C code.

You didn't answer about the O2 sensor. The guys here say Bosch sensors are trouble and to use NGK/NHK and I take that as gospel.

I wonder about misfire codes because unequal fuel distribution will have the systen struggling to find a good a/f value. Junk in the fuel rail can starve #1. A leaking injector can cause a rich condition at startup. It can contaminate the oil with fuel, then with engine heat, fuel gets driven and impacts a/f.

If there's something wrong with the fuel pump it could be sending debris downstream. You weren't wrong about considering injectors, but you wanna be sure you fix any underlying problem before you mess with those.

Oh, yeah, I just remembered that when I had this issue the car had the original OE battery, ten years old. I have no idea if replacing it helped, but these cars are notorious for electrical weirdness under low-voltage conditions.