Hello Everyone,

I'm the noob here. I couldn't quite find an intro thread so if there is one, please direct me to it.

I have an '07 Tech. It recently threw error codes P0171 Emissions System and 77 AWD system. I cleared them and they didn't come back until today, about two months later.

My questions are, can anyone clarify these codes for me? From what I've read, it could possibly be the front o2 sensor? But then it could also be myriad other things.
And the 77 code I'm completely miffed about.
The car has been acting funny since it first threw the codes, during acceleration, it seems to hesitate or stumble, as if the ECU was cutting spark for a split second. Leads me to believe it's the o2. But I've seen advice like cleaning the MAF sensor and such..any guidance or clarification would be appreciated.

Sorry if this has been covered, I'm sitting at the office and don't have lots of time to search and comb through old threads. Please bear with me

 

The AWD77 code seems to accompany several different emissions codes, but I cannot find a reason why as emissions has nothing to do with the AWD components. Perhaps it's a safety measure, as depending on the emissions code your vehicle's driveability can be affected. I would focus on the P0171 first, and once resolved see if that also eliminates the AWD code. If not, diagnose from there.

Here are the basics on P0171. I'd start from easiest/cheapest and go from there...intake leak should be easier to detect and cleaning the MAF only takes a few minutes. After that it does become a little harder to pin down stuff, but I have seen one or two posts about a clogged cat before.



P0171 - System Too Lean

Symptoms:
Typical symptoms of the lean air fuel mixture include:
- Lack of power
- Rough idle
- Hissing noise from the engine (vacuum leaks)
- Stalling
- Difficulty starting
- Engine knock or detonation (pinging) under load
- Engine running hot

Causes:
Common causes include:
- Intake or vacuum leaks
- Clogged or faulty Mass Air Flow sensor (MAF)
- Faulty PCV valve
- Stuck open purge valve/solenoid
- Faulty oxygen sensor
- Improperly installed aftermarket cold intake
- Low fuel pressure
- Clogged catalytic converter

 

Yeah I was able to spend some time last night doing some research. It seems the AWD pops up as a result of the emissions. Apparently it puts the drive train into a safe mode in order to reduce stress on the engine..or something. Idk, it makes sense.
I plan on cleaning the MAF this weekend and searching for any potential vacuum leak. I don't quite know how to go about doing that. I have a can of starting fluid I can use, but aren't I supposed to unplug some sensor or another? Like the TPS?
I've also had a look at the location of the O2 sensors and I don't think it's something I can do without a service manual, which I don't have so if cleaning the MAF doesn't help, into the shop it goes.

 

For intake leaks, try playing it by ear first. Listen for any hissing sound under the hood. If there is a leak that is throwing off your a/f ratio to report lean, and assuming you are having no boost issues, it will be after the MAF and before the turbo, so not a huge area to cover.

If the leak was after the turbo, you'd be losing air from the system as opposed to pulling in unmetered air, which would then cause a rich condition instead. If you had a leak big enough to let air in post-turbo, you'd also never be able to go into boost and it should be quite noticeable.

 

Thanks for the information tomtwtwtw.

 

I found the problem

 

Looks like a perfect reason to get a CPE

 

good job finding the issue yourself with a few pointers from those in the know. and yeah the CP-e is a great intake with a proven track record, another + is that you dont need anything else to use it.

that said i know a guy that's getting rid of a flash pro and injectors. just a thought if you want more...

 

Thanks guy. I have a decent working knowledge. I did a lot of work myself strapping a snail to a GSR I had. Minus the tuning and some fab. I'm interested in the ALTP exhaust, flash pro and injectors but I'm not in the position yet. I'm glad the intake will work solo, I was actually trying to figure that out. I'm just trying to figure out what kind of filter I should run with it.
I've also been looking at some of the stuff you've done. You actually aren't super far from where I just bought a house up in Forks Township.

 

Good find there, definitely an opportunity to upgrade to a better part for probably the same or less money than an OEM replacement.

 

So it turns out CP-e is in Beltsville, MD. A few miles up the road from my office. I called them to see if I could pick up the part and unfortunately its back ordered

I do wonder if they need an RDX development vehicle