I have the following codes on my car and the check engine light is on,

17544 - Fuel Trim: Bank 1 (Add): System too Lean
P1136 - 001 - Upper Limit Exceeded - MIL ON
17546 - Fuel Trim: Bank 2 (Add): System too Lean
P1138 - 001 - Upper Limit Exceeded - MIL ON

I guess one starts with checking the vacuum lines first, or should I check other things first?

I was inspecting the vacuum lines at the rear of the car and there is one component "vacuum diaphragm?" which I noticed was taking in air at the top where there is a small gap is this normal? see attached pic of the part.



Anyone have a schematic of the vacuum lines as the Bentley Manual seems disjointed.

I also noticed that the vacuum pods "links" plastic were broken. I popped them of and put on the aluminium ones from www.GruvenParts.com. But the car started to blow white smoke from the exhaust, not sure if all this is related.

(A8L 2004 BFM engine)

 

That is your PCV valve (crankcase vent). It should not be sucking in air from outside...that could be introducing unmetered air (major vacuum leak...ruptured valve?) into the intake, which would cause a lean fuel-mixture condition.

The links on the front of the intake manifold control your intake changeover...different lengths of intake tubes for different rpm ranges, to keep torque curve up through the range. Should not effect color of exhaust smoke. This system is working properly if both vacuum pods connected to those links are full (blown up) when engine is off....and both fully evacuated (sucked in fully) as soon as the engine is started and idling. If they are NOT doing this see this procedure: http://forums.audiworld.com/showthre...2801728&page=3

BUT, that procedure has nothing to do with lean burning condition.
You need to check out the PCV valve (your photo)...as I stated, should NOT be sucking air on top of the valve...likely your "lean" problem.

 

Old thread, but I have the same codes P1136 and P1138. I'm wondering if it's the MAF or O2 sensors. I have 135k miles on my car.

Does anyone know the specs to test the MAF with a multi meter?

 

I have the same lean codes. both banks. checked vacuum lines, cleaned the MAF sensor, no codes for oxygen sensors so I doubt it's that. Also no code for MAF sensor. Just lean bank 1 and lean bank 2. I also have an issue with blue smoke from the exhaust, but only after it sits at idle for 15 or 20 minutes and then sits over night it will smoke at start up. If I drive normally, it never smokes at start up, so I don't think it valve seals. I will check the PCV valve. That sounds like a common link. How do I check this PCV valve ?

 

I changed the PCV valve and that fixed everything. You will notice it sucking in air. Its the one in an earlier picture.

 

GREASE - Thanks for coming back to confirm, my PCV valve has that open space like yours. They could all be like that but maybe the internals failed causing the leak/codes.

I found one for $84.00 on RockAuto.com , I might just get it as my car has 135k miles.
More Information for STANDARD MOTOR PRODUCTS V465

 

I assume there's no fix other than replacement ?
I will dig into it and post the results. could take some time as I have a lot going on personally.
thank you so very much for the point in the right direction !
there doesn't seem to be a ton of know how on these cars and engines on these forums. Seems most like the smaller cars, and that's what they know.
please keep posting your experiences. I will too.

 

I ordered the PCV Valve from RockAuto and I'm going to put it in this week, I will report back to see if it removes those two codes.

I also need to fix my driver's side flex pipe exhaust leak. I don't think that is causing the two codes because I would probably only get one bank reporting lean not both.

 

The PCV valve is not fixable, you will notice it sucking in air at the top of the valve center, pretty load hissing coming from the top of it. Feel air going in through the center?

 

Installed new PCV valve but the light came back. I'm going to check the MAF measuring blocks as well as fix the exhaust leak. I'm not getting any strange O2 codes so it's probably not them. I'll look around, but I don't think I have any vacuum leaks