New to The Forum. Used it a lot but never wanted to post. Have a 2007 HHR Lt panel with a 2.4 motor . At my wit's end. I have code P 0171. Tried all of the following: new fuel injectors including new gray cylinder head adapters and O-rings, replace entire emission canister system both Valves and canister, new manifold intake seals and new manifold MAF sensor map sensor, two different throttle bodies blocked-off brake booster, change door block off all hoses wild reading vacuum gauge new gas cap from Chevrolet. Vacuum still reads about 17. Drugs fine and gets excellent gas mileage, idle is okay so is the temperature using premium gas. Don't hear any weird exhaust noises. I bought the car with 80,000 miles on it 10 years ago now has 208,000 on it. I do all my own work Enterprise very little trouble with the car other than staying on top of the maintenance. Anybody want to take a shot? .

 

Welcome to the site, the P0171 would indicate a possibility of a failed MAF , however mine was a cracked flex pipe , my second P0171 turned out to be a failing fuel pump.

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

Now you replaced a lot of unrelated parts like injectors. Have you tested the fuel pressure? Seeing as you don’t hear exhaust noises.

 

Welcome aboard.

 

Welcome
There's your problem. Up above in RED. Lay off the drugs my friend.

Seriously though. Listen to Oldblue. He'll steer you in the right direction.

 

Is the problem with the HHR or the Enterprise? Maybe it just needs new dilithium crystals.

 

My vote goes to the crystals or the fuel pump.

Vacuum where? Crank case vent should be less than 1 inch Hg.

crankcase vent hose tight? Intake horn leaking/ loose. The point where the hose enters the horn is subject to cracking.

 

 

​​​​​​ thank you for the response. I checked the fuel pressure but I have done so much to it I forgot what all I have done when it comes to putting it up on the internet. Fuel pressure was 55 lb and maintained it for about 6 or 7 minutes. I didn't check to see if it leaked beyond that. It had several problems as your fuel injectors definitely brought back the fuel mileage. I've tried two different m a f s. It is going to the dealer tomorrow to have the ignition recall addressed I'ma let them see what their diagnosis of it is. Seems to be about 3 inches low on the vacuum and sure behaves if it's a vacuum leak but I can't find anything, even after swapping out hoses and plugging everything off