I recently got a 2000 A4 1.8TQ Tiptronic with 109K on it. The check engine light is on, and the only code the Vag-Com gives is P1136 (17544/P1136/004406 - Fuel Trim: Bank 1 (Add): System too Lean)
I recently changed the spark plugs and put in a K&N air filter. My mechanic replaced the MAF sensor and O2 sensor, together with a cracked air pump valve (?) to fix the problem, but the Check Engine light is still on. He says he couldn't find any vacuum leaks. (I think he only did a visual check)
The car feels sluggish, and seems to be losing power after 60mph.
Where should I look to fix the problem? Is there a vacuum hose diagram that I can use to double-check leaks? Any input is highly appreciated.

ps: the oil dipstick funnel is loose, it comes off with the stick. I just ordered a new funnel. can this cause any power loss or check engine light?

Thanks in advance

 

anyone?

 

Have you found anything out? I am having the same problem. I had this problem before and it was my maf. I would reccomend doing a vacuum pressure test. Its pritty easy to make your own and you will be able to hear and feel the leak. Let me know what you come up with. I am definitely interested because I cant seem to find my problem.