SeeksAR

Reminds me of the Jack Sprat poem.

Last month, I scanned w/ Vagcom and got a "too lean, bank 2" message. It didn't trip the CEL. I was just scanning for fun. I reset, checked my air filter box to make sure I didn't have any leaks, peeked at my MAF (was still intact and looked clean). Dumped a couple of STP injector cleaners thru the gas tank. Everything went fine for a couple weeks.

Yesterday, got a CEL on the dash. Vagcom says "Too Rich bank2" now. Double checked with Acton scanner and got P0175 "too rich bank 2".

Any ideas? Time to change MAF and O2 sensors?

An

Kristopher

I wonder if a boost leak at vacuum could cause the 'too lean' and then under other conditions (more aggressive) it'd be too rich in moderate boost.

fjasper

Mine did something similar to this, and I never positively identified the cause, but after I replaced the fuel injectors for a different reason (they were leaking fuel in very cold weather) it went away. I suspect a bad fuel injector o-ring, but I suppose it could have been an injector or even something I disturbed while I was working on it.

Before replacing the injectors, I replaced any vacuum hoses I could find. Others suggested fuel pressure regulator, and probably some other stuff I don't remember.

Depending on your time/money ratio, you could try swapping the injectors to the opposite sides of the engine and see if the problem follows the injectors or not. Don't skimp on o-rings, cleaning, lubing, etc. if you do that. I ended up tearing an o-ring when I did mine, and it leaked air bad enough that I could actually hear it at idle. FWIW, the brown o-rings they had at the parts store were the right size, but they didn't seem to hold up very well-apparently they weren't the special rubber (viton?) the 2.7t requires.

Hey, I just remembered what it might be-check your throttle body boot on the front of the engine. You might have to take it off to be able to inspect it thoroughly. They're kind of notorious for cracking.