P0172 now...was P0171...

[Backporch73]

So now it's saying PO172 system too rich.... Two days ago it was system too lean. I am going up an elevation and down in the mountains could that have anything to do with it?*Any advice is helpful thanks

2007 Hummer H3
I5
​​​​​​​148k miles
Air*doc*

 

[Backporch73]

Changed air filter to an item style disposable, code reset and it hasn't come back. It was just incredibly weird because I just fought a po171 engine too lean, and now I have a po172
And tell him to fix it too cuz I clean the MAF sensor MAF assembly replaced the air filter and replaced the spark plugs. So far so good...well see.

 

[alrock]

Vacuum leak is one of the possible symptoms, right? If it comes back, maybe put on the OEM intake vs. the AirDoc to eliminate that as a source. Also verify the little PCV hose at the back of the engine from the valve cover to the intake is intact. I don't recall how it hooks up with the AirDoc but with the OEM setup they can become oil soaked and begin to fall apart.

 

[08H3]

Good advice on the fresh air intake hose. They will totally fall apart over time. A cracked airbox would also cause a lean (but not a rich). I had that happen last year. Never set any codes though. I also have an AirDoc and I think it puts more stressmon the airbox connection than the OEM since it offers no flex. Something else you might check.

 

[Backporch73]

Well guys I did all that made it home okay and been driving around since. No real problems and I know of. I do feel like I have a bigger vibration at idle at times..but no.more codes etc. So who knows? Either way I'm very skeptical about traveling in my rig again