CEL - System Too Lean (P1136)
 

Hey Everyone,

So I've had this CEL for a while (P1136 code) and I've searched and tried a few things to fix it.

Background:
99.5 Audi A4 1.8Tizzle, had a busted catalytic converter that gave the same code when it popped out of it's flange. I jerry-rigged it so it would stay connected, and after that the CEL went out. Installed a Labree HFC and a few days later the CEL popped back up.

Symptoms:

Car idle's a bit funny when in park/neutral, in drive everything seems fine. My gas mileage has been crap, and sometimes the car hesitates when accelerating WOT.

Solutions Tried:

Searching around it seemed that a lot of the "potential" issues were with either the MAF or front-o2 sensor. I cleaned the MAF and replaced the O2 sensor..........all symptoms still persist unfortunately.


Anyone have any other ideas what it may be? I might break-down and taking it to the local Audi Dealership here since I don't want to keep guessing/buying new parts. Thanks in advance everyone!

--Asif

probably need to replace the MAF

If it was my MAF though
 

I read that my car would be having trouble even starting....and die potentially at idle, which I don't have

Mine went bad and I had the same code. I never had the issue you are describing
 

with it not starting or dying at idle.

hmm I'll check with vag-com
 

But it just doesn't seem to make sense if one day there is no CEL with a ghetto-rigged OEM cat converter, and the next I get the CEL with my labree...

More searching seems to be possibly linked to vaccum hoses/exhaust related<ul><li><a href="https://forums.audiworld.com/a4/msgs/2639854.phtml">https://forums.audiworld.com/a4/msgs/2639854.phtml</a</li></ul>

Re: When in doubt... MAF.
 

I had a problem about a year back with my 99 1.8T Passat: sagged upon acceleration from a stop.

It was the Mass Air Flow (MAF) sensor. They are known to go bad. I am unaware of a definitive test.

"Lean" tells you the perspective of the engine -- NOT whether any particular sensor is bad -- or if a sensor is LYING to the computer.

I tried the spray cleaner trick. No help.

It is an easily user-installable part, about the size of a half-height coke can. In the Passat, it is located under the lid of the air cleaner box. Doubtless same on A4 1.8T.

The way they work is that engine electricity warms a verrrrry thin wire. Rushing air COOLS the wire. The engine computer translates this varying resistance into air quantity measurement. Verrrry sensitive to changes over time in the filament's resistivity, conductivity, etc. When your car is idling, the filament warms up. When the widget is misbehaving, a sudden rush of cool air does NOT generate a corresponding injection of FUEL, hence the puter says "Lean." When the car is motoring along, the misbehavior is not as obvious.

To other earnest responders on other strings who suggest one of the O2 sensors, I ask, "Why only pulling away from idle?" Eh?

ECS Tuning has a bunch.

Cured the problem, improved general engine performance muddiness, and mileage.

Best wishes.

Anyone else?

I'll have to log block 32 and see
 

if it really is the MAF. Thanks.

I had that code and issue. Turned out it was bad fuel pump. Might change filter as well.

I had an air leak where the Intake Hose (30) connects to MAF (4)..
 

whilst MAF itself is inside Air Filter Housing(1).

Namely, the hose partially slipped off, perhaps due to hose deflection during filter change.

I found out about it only when replacing MAF after getting the lean code.

I am convinced my MAF was good and lean code occurred after fast highway ride when demand for air is high.

There is a clamp holding the hose to MAF, nevertheless it managed to slip slightly off.

<img src="http://img.photobucket.com/albums/v136/vladlesh/A4/A4.jpg" border="0" alt="Air Intake">