BERNS

Hello All,
I am having a hard time getting my '07 2.2L to run right again. I moved and my HHR was sitting for about 3 months and when I took it out for a drive it started shifting hard and the check engine came up. Scanned it and P0171 came up.

I checked fuel pressure and it hold around 55, does not drop after sitting for a few mins. I cleaned MAF, checked terminals for any issues and nothing. Also replaced TB cause it was sticky and did not function well after a cleaning. Cleared the codes and took it for a spin, normal shifting and all until a few miles out and it started shifting hard and CEL came on, again P0171. Checked evap solenoid and hoses for any issues and all checked out. Pretty stumped after going through it.

Questions I have are, does bad gas from sitting for 3 months cause this code and where would it be optimal to hook up my smoke machine to see where it might be leaking from? Also, would it be ok to put smoke into the exhaust system via the tailpipe to see if the flexpipe is the issue?

One thing to note is that I never had issues when I used to drive it daily. It started when I began working remote and rarely drove it. Might be a seal and that is where I want to use my smoke machine to test.

PulpFriction

Is there any chance that someone put E85 fuel in the tank?

Oldblue

https://www.obd-codes.com/p0171

I’m thinking flex pipe, however it could be other places for an air leak. Smoke it, see where it’s leaking

donbrew

Make sure the EVAP purge valve (under hood) is working, it is normally closed, so blowing into it should not be possible.
I have never heard of anyone finding a leak with smoke. Maybe, a properly equipped shop could get results.

You probably think the code means that the A/F is lean, that is incorrect. It means that the TRIM is going lean because there is too much fuel or too little air in the combustion product. A stuck open EVAP purge valve causes gas vapor to flow into the intake manifold after the injectors, thereby upsetting the A/F.

BERNS

Doubt it cause the last time I filled up was with premium and there is no E85 pumps around me. But thanks, that would have been an issue if it was filled with E85 and not being flex fuel vehicle.

BERNS

That is my thought cause I just noticed a strong fuel smell under the hood this morning when I lit it up but it is also coming out of the exhaust pipe since it is running rich due to leak. So I will see if I can smoke it.

BERNS

Replaced the solenoid but when blowing through it, one side will allow to blow through and the other it won't. Checked it with another one and it was the same. My old one was the same way. Are they not supposed to allow air from both ends?

I know it is running rich cause I can smell it when it is running so it is pumping more fuel than normal. Gets to a point that I can't stand the smell and have to shut off after testing for a few mins.

BERNS

Thanks to those that responded.

So where would I hook up smoke machine without harming anything else?

Oldblue

The purge valve under the hood should be closed both directions. You should not be able to blow air thru it .

PulpFriction

Is that after it warms up or only upon startup?

I would inspect the fuel system from end to end under pressure and eliminate a fuel leak before going after an evap leak with smoke. The fuel line (as well as the evap line) is notorious for leaking due to corrosion, in particular near the lr wheel, but anywhere from the tank to about mid-cabin. There are some small foil-wrapped insulation blankets that can soak up the fuel, preventing tell-tale puddles on the ground.

The fuel system should hold 55-60 psi after shutoff, for, idk, 10 minutes? I don’t remember. If it doesn’t, it could be a bad check valve (in the fuel pump I think,) but if not it’s probably a fuel line leak or a leaking injector.