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Problems/Service/RepairsIf you have a problem with your HHR, want a tip on repairing or performing a particular service to you HHR here is the place to post!
The "ambient" temp reported to the OBD2 is from the MAF, it is used for air volume calculations. The temp on the dashboard is from the under bumper sensor.
Okay since scanner might not be that accurate I’m getting a fuel pressure tester kit from a guy. He did ask me if the HHR 2.4L came with a high pressure fuel pump?? Does it?
Also what are the pressure levels with key on run position supposed to be? 50-70psi at the rail? What about when engine is off the same?
What about fuel pump psi?
After the engine is shut off how long should we look to see if any drops in pressure and how much is too much?
Bumping this thread. 2011 HHR 2.4L with 162,000 miles. Just got a P0172 code I have been chasing for a few days. Here is a list of what I checked.
Purge valve under the hood I could not blow through so it’s good from what I read. Can’t find any vacuum or exhaust leaks. O2 sensors were replaced 60,000miles ago, scanned the engine and looked at all the values running and not. O2 sensors looked fine, all fuel looked fine. It was time to change my air filter and spark plugs so I did. Cleaned maf sensor, it and map and IAT all read good. No compression issues.
Here is some info about the HHR. I only drive it 6miles a day five days a week. It doesn’t see full operating temp I’m almost positive in such a short low speed drive. Locals here have been having issues with a gas station I just have happened to be filling the HHR up with not our other car. A bunch of people have had engine issues, either alcohol in the gas or water. So I bought a bottle of HEET and added to the fuel tank I already had.
Have done a lot of reading about alcohol levels messing up flexfuel cars, that and fuel trim levels need to be set back to zero. Not sure my buddys scanner can do that. With new air filter and plug change it starts great and doesn’t chug but did notice after sitting 12 hrs and it was 66 outside this am it started right away just maybe kinda reved down quick?? Before it was a weak start then kinda rough idle then never again unless really cold.
So this am it was 66 degrees and I drove it for alittle over 3hrs. For several miles on a highway doing 45-60mph and giving it good joints of the gas pedal and it ran great. No smoke from exhaust from the so called rich code. Only thing I noticed is at that temp out and me getting on it to 80-90mph the digital temp only read 169 the highest. Then I came home for a few mins left it running and go in. Temp read 212. Went 20 miles away and left it running in a parking lot and watched the temp go from 170ish to 217. Then it slowly went down to 170ish. Then driving back home again it stayed at 170ish with outside temps at 69. I have read coolant sensor can cause P0172, and thermostat as well.
Does anyone else think my cooling sensor or thermostat might be the issue with the colder starts? Engine reads a different temp when key is turned and adds more fuel…
I don’t.
Everyone’s forgotten this thread, which helped me fix P0172 last year:
I had very precisely the same situation as the OP (not this thread, the one I linked to) with our 2011 2.2L.
203 posts over almost three years. Much chaff, much fruit of insights of resident experts. Very interesting tho, if you’d like a deep dive into how flex fuel works and what can go wrong.
TLDR, a flex-fuel HHR get can get confused about the amount of ethanol in the tank. You need a scan tool to check when the car thinks its ethanol % is. Dollars to donuts, it’s way too high, and needs to be reset. Mine thought it had 50%, even though it was fed 10%. It started hard, ran horribly rough and smoked, because it was injecting way too much fuel, thinking it was 50% ethanol. Once it got warm enough for the oxygen sensors to work, it would go to “close loop” mode, realize this, and correct the mixture to something much leaner. P0172 obviously meant in this case the computer thought the required correction toward lean was too great and something must be wrong.
As far as I know, it can only be reset to zero, but that’s close enough if you’re pumping E10, apparently. My car continued to operate thinking it had 0% through several fill ups, seemed maybe a little lean on startup, then one day I discovered it was set at 11%, consistent enough with the supposed 10% max I was buying.
Better half was reminded to strictly be sure to turn off the car when refueling. The one place that sells E85 in our area charges way too much for it, so that won’t be an issue.
Last edited by PulpFriction; Jan 7, 2022 at 03:07 PM.
If you are worrying about too much ethanol in the tank don't put HEET in it, that is methyl alcohol. Produces the same gasses when combusted.
BTW, donbrew, I want to mention it was your explanation that helped me understand how the system calculates the ethanol level, leading to the solution, so thanks for that. There were a few points about that that I’m afraid the curious with have to excavate from the thread.
Last edited by PulpFriction; Jan 8, 2022 at 05:21 AM.
Just to update this post. What I have found is the port on the valve cover that has the rubber hose that connects to plastic elbow on hose to throttlebody. It won’t blow any vapor at all. Revved the engine a few times and used a air hose to blow into it. It started pushing air out. Three days later it’s not pushing anything out again. Vapors come out of the oil filler neck though if you remove the cap. So to me seems like I will pull valve cover off and clean it out. I always change oil on time but the HHR did sit for a year only being started for battery help for a few minutes or once a month tops a short 2-3mile drive and back.
Have been watching the thermostat and seems to be working fine might have been kinda stuck before. But at 20 degrees outside and letting it warm up for 5mins then driving it a mile away and sitting in it for another 20mins. Temp only got to 167. I would assume that’s normal with temp outside and short distance driving. Fan does work also.
