Any piece of 1/2" rubber fuel hose will work just fine. Go to an auto parts and buy a foot, cut it to length, it does not need to be an "s" shape.

Disconnecting a battery on a GM vehicle does not clear any code. When emission related, it may turn some off until the vehicle reaches full operating temperature when the PCM will read the condition and turn it back on. All post 2005 GM vehicle store everything for the last 300 ignition cycles, battery or no battery. Think of a flash based thumb drive. To clear it, you have to write over it (ie. clear with a scanner or PC Tuner).

 

Great info, thanks Doc.

 

to make a short bend i make a loop, longer hose.

 

I put in a new breather hose a couple of weeks ago. Definitely makes a tighter connection than the old hose did.

I installed a new (to me) resonator this weekend (thanks 2hummers). Cleared the codes with a scan tool. The check engine light came back on about 4 miles into the next trip.

Went ahead and bought a new MAF sensor, installed that, cleared the codes again. The check engine light came back on less than 2 miles later.

I've checked all of the screws, bolts etc. Everything is nice and tight with the exception of one rear bolt on the box that holds the air filter. The bracket that holds on has a small amount of play in it. I tried tightening it, but it seems to be pretty frozen. Could that being loose potentially cause a problem? Guess I could spray it with some PB Blaster if getting it tighter could help.

 

You have an intake leak, or your PCM thinks you have one, keep focused on that.

Way back in your opening thread, you mentioned a new air filter replaced last month. Is that OEM or aftermarket?

Open the lid on the air filter box, is the air filter canister opening slid all the way over and onto the outlet flange, is the filter in proper position. At the closed end of the filter canister, there is a plastic pyramid thing molded into the bottom of the air filter box, that is supposed to be pushing against the closed end of the filter holding it to the Right onto the outlet flange. If it vibrates out of position, you have an intake leak.

No, the feet holding the air filter box to the fender will not cause a leak if loose.

 

Thanks Doc. I'm focused, I'm just running out of parts to focus on, lol.

Just went out and rechecked the air filter canister. It's well-seated in the proper position. I re-seated it just in case. I'm pretty sure it's aftermarket. Honestly, I've never paid attention to the brand on air filters. Would it be good to try putting an OEM one in there?

 

i thought an intake leak would be after the maf where air is measured. cant u run ok with no filter?. not clean,but...

 

Typically that is correct, a leak after the MAF.

However, absence of a filter/or filter out of position will allow excessive air to enter the system and the PCM can recognize that as lean by cross referencing expected MAF and MAP. MAP also calculates absolute air mass in the intake manifold and can recognize when the system has more than the pre-programmed parameters of intake air. It may take some miles before too much air is recognized triggering a lean bank code, but it can happen.

So..... if your filter is right where it is supposed to be and you 100% ruled out any possible intake leak, forget all that.

Now check to see if you have a broken exhaust manifold bolt or two, more likely at the rear of the engine, like the back 2? If air is getting sucked in the exhaust before the first O2 sensor, you get the same code. You should hear a tick or exhaust leak, but sometime that is harder to do that one would assume.

I still say run it on an advanced scanner to see what it is doing.

 

Thanks for the feedback.

How easy is it to remove the heat shield so I can get to the exhaust manifold? I took a glance this morning and it looks like there's a bracket for the a/c line sitting right on top of one of the heat shield bolts. Can I get the heat shield off without removing other things around it?

Also, once I do get the heat shield off, will I be able to tell if I have broken manifold bolts with a visual inspection, or do I need to keep pulling things apart?

I'm an apartment dweller, so I have to make plans to borrow a friend's driveway if I'm going to be spending more than a few minutes under the hood.

 

I took the car to my local mechanic last week. I'd also been having problems with the car not wanting to start. My original plan had been to address that after I solved the P0171 issue but since I was dropping it off, I asked them to have a look at both.

It turns out that replacing the fuel pump took care of both issues, they suspect because of a fuel pressure sensor that got replaced at the same time.

At least the code's gone, the light's off, and the good people at the State of Texas have a registration sticker in the mail to me.

Thanks for everybody's feedback in going though all of this. If nothing else, I gained a lot of confidence in knowing that I can do many of the minor service items myself.