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.

 

I'm almost certain the ESC was disabled and clearing that code reactivated it hence the chiming from the car. I did answer in the previous comment that the upstream O2 was replaced. Luck would have it though that I used a Bosch sensor. I doubt Autozone will take it back still. That has been acting Ok and getting the numbers it should be on the scanner. I'm tempted to just put the old one back in as it was reading ok too BUT I think I replaced that years ago with a BOSCH, i don't remember.

I have not found one misfire code. Changed the oil last weekend. I have pulled the fuel rail and left ignition on for 30 mins and checked for leaky injectors and so far haven't found that to be the issue. One thing I have noticed though is at the injector port, where the cup with the 0-ring goes, there is a slight little puddle of gas/oil mix pooled up in there on the lip. There are all new O-rings on those cups and injectors. I sprayed carb cleaner around all them with the car running and no leaks. Where's that oil/gas mix coming from?

This new scanner I bought is a bi-directional scanner. It is so much more useful than just a reader. I rechecked the fuel comp. and it's sitting at .5 %. Was also able to reset long term fuel trim. Was watching data stream while doing it and it is reading around -3 trim now.. But when i exit diagnostics and go into OBD2 long term trim reads -14. I don't know enough about scan tools yet but it appears there are different long term readings in different menus.

I was also able to clear the adaptive functions on the transmission. That had not been done since replacing the trans. A lot of guys say it would relearn itself but I cleared them anyways. I'm replacing fuel pump tomorrow. I bought a new fuel pressure guage and put it on. Pressure starts at around 54psi but the needle starts to drop. It's very very slow but fact is it's dropping and you can see it on the needle. i'd say maybe 1psi per minute. My question with this is doesn't the fuel pump maintain a steady pressure when the car is running. So even if it was leaking won't it overcome the leak while the car is running? I checked with car running at it holds steady at 60psi

 

The O2 sensor is crucial for this system.

How much of a problem a leak is depends on where it is, I surmise. Your problem could just be a failed fuel pump check valve. A leaking fuel injector is bad news.

Fuel pressure leakdown has been associated with the stored ethanol % problem but IDK if anyone can explain why.

What scanner did you get, exactly?

 

I bought the Launch Creader on amazon for $179. Not the best but it works great for me. I'd really love to get the Autel MK808 and almost did. But I looked up the price to update the software after the first year and it's a quarter of the price of the scanner! I will not use the thing enough to justify paying that. Now, from what i understand you can continue to use the scanner without updating it. The Launch Creader will lock me out after a year is up but is only like $28 to update the software. Also have to buy software if I want to diagnose anything besides GM. But the code reader is universal. I think with scanners, you're going to always find another one you like after you buy one so just tried to stay cheap for now.

Lets see what happens tomorrow after i replace the fuel pump. Up to this point, I had not heard anyone relate fuel pressure loss to the stored ethanol % problem. That is interesting and certainly does seem quite relevant. I'm fairly certain the injectors aren't leaking, at least on the injection end anyways. Is there a better way to test them? Could you maybe submerge each one under fluid and watch for air bubbles or something of the nature rather than just pressurizing the rail and leaving them out a waiting to see if the dribble.

The o2 sensor is easy to change. If I have to get another one then i guess it's just what has to be done. Will have to change the downstream one then too as they will be two different brands, unless the downstream is not as crucial. Was hoping someone could chime in about why i'm seeing two different data streams on the scanner for long term fuel trim. The data stream that comes up when doing the trim reset is showing fantastic trims however when I exit reset functions and go into the data stream through live data that trim is the one showing -14 on long term trim. Why is one more than the other?

 

Scanner updates are more important if you buy a later car.

I have no idea if a Bosch causes trouble after the cat but it’s definitely less important unless you gotta pass inspection.

Might be showing a meaningless 0 long term trim for bank 2, which you don’t have? Not clear exactly what you’re seeing. Frankly, if the the car doesn’t complain about the trim, I wouldn’t worry about it much, even if curious. Watching the the short term trim bounce around is also interesting. (I do this with my free Torque app and Bluetooth dongle. Easily entertained, I guess.) As you know, P0171 & P0172 are the complaints of which I speak. “Once in closed loop, I’m successfully trimming to an acceptable a/f but I think it’s more than it should be.” The car has no idea what the a/f is while the O2 sensor is still cold and it’s in open loop.

 

Well, back on here for more help. Put fuel pump in last Saturday. Replaced lines right away too. Put all back together. Fuel pressure great, no leak downs, fuel trims looking good now too! Drove car for two days and got a code P0451. Put scanner on and says Evap system pressure sensor circuit or something equivalent to that i don't remember exactly. Went to diagnostics and was able to actuate the vent solenoid successfully as well as the purge solenoid. Also tried blowing through vent solenoid while in closed position and it's definitely closed. Same with purge solenoid. I checked evap system sensor vacuum reading and its saying -1100Pa which converts to like -159 psi. From what I understand system should pull negative but not more than 14 psi.

I did not have this code before of course! I started going back over everything I did. From what I understand this code is more about voltage than mechanical but regardless says check for leaks, etc. Gas cap seal looks good but i cleaned it and even a little silicone on the seal. Solenoids all working properly. I unhooked purge line from the canister at back of car and was able to successfully pull and hold vac on the purge line however when i try to pull vac on the purge line from the engine side (purge line back on canister) with vent solenoid closed I can not pull a vac. Purge line was a suspect since I had replaced it and used a compression fitting towards front of car. But it pull vac fine from the back just not from engine side. So does that mean there's a bad seal somewhere? Only seal I had to mess with was the one for the fuel pump, the big O-ring that goes on tank. I've changed this pump before so I have the tool to lock the o-ring and i'm absolutely positive the retaining clamp was completely locked.

But now I'm thinking, if that o-ring isn't seated properly wouldn't that throw an evap code within minutes of driving the car. I've cleared this current code twice already and it never comes on while i'm driving the car. It's always after turning the key seems like before the car is even running, before it can even do an evap system check.

It's a brand new fuel pump. I doubt the pressure sensor is bad but why is it reading those whacky numbers? Maybe loose pins in the harness either behind back seat or at the sensor itself?

Trying to figure out with the help of more experienced owners what is most likely to be causing the code. I'm not looking forward to dropping the tank again and aimlessly looking for a clue.