I've read a couple of threads with my similar problem but want to get any new feed back or discoveries

A4 Avant 1999 1.8T 5sp 157K
Issue - intermittent sudden lose of power that can be best discribed as AC kick in except 10x worst. When it is acting up, and stopped at a light, it will hunt at low idle and often stall. Problem is intermittent and some day car runs normal. CEL comes and goes. It almost seems that it is electical connection issue. What ever, problem is now more frequent and will show up during every second drive.

Done to date, but no resolve

Fixed vaccum leak at airbox check valve (split)
replaced fuel (pain) and air filter
properly cleaned throttle body, MAF
spark plugs OK
Pulled codes at Auto Zone- P1136 and P1127

Similar threads suggest the MAF needs to be changed ($$). I would like to be sure this is the issue. Is there a simple test to confirm MAF?

Could the cat converter be plugged? wouldn't that be a continuous issue?
Would O2 sensors ($$) be bad?

Please suggest.

 

Can anyone suggest anything here? It is now acting up continously

Shappie

 

I had a similiar issue. My car would idle rough or up and down the rpms would go or sometimes it would stall. Recently the last 3 times I filled up my tank the car would not start, eventually it would. I ended up having the "pressure regulator valve" replaced.

 

im having the same problem and im buying a maf sensor tomorrow so ill post back when i get it on. I also took my car to bob moore audi to have them pinpoint the problem before i spent a ton of money and this was my reply Quote C/S Check engine light is on. Check and advise. Check and cleared fault codes. Engine is Highly Modified. No further diagnosis can be done........... what a load of **** i got the experts scratching their heads

 

unplug you maf flow sensor and see what the car does for some people its better if so u need a new one

 

I ended up taking my car back the following week beacause the check engine light came back on after the pressue regulator valve was changed and the dealer said there was a vacuum leak they corrected. Same day check engine light came back, I'm tired of running back and forth to the dealer.

 

There's a good chance it's the engine speed sensor.

 

I'm holding money on MAF if its bad it wont matter how many times you clean it. My did the exact same weird idle at lights and stalled some times with CELs sometimes not...

 

Ok maf censor did not work. check entire engine bay for vac leak no luck there. ( used carb cleaner while running) i think im just going to start replacing everything one peice at a time.

 

chances are it is a defective sensor that has caused other problems bc you continued to drive it(probably drove it hard) while it had the problem. check if it's the engine speed sensor/ crankshaft positioning sensor other than that id look into getting something different. seems like youre just getting started with these problems and the car is in bad shape