Hey everyone I could use some Audi Guru help here. My girlfriend bought an A4 a couple years back and I have pretty much done all the mechanical work on it since, but I have run into a problem I cant tackle here. The car is a 1998 Quattro 2.8. The problem is that randomly the idle on the car drop from perfectly normal to 200rpm or below and then proceeds to stall out on occasion. The problem seems more severe in the cold than it is when its warmer outside, but the problem is still there in all conditions, and it is very intermittent.

I did a tune up about 5,000 miles ago, plugs, wires, and air filter. When the problem first started I just assumed fuel filter, so I replaced that. The old filter was pouring out dirt fuel, so I thought problem solved, but no. So then I found out about this pcv system problem with the B5's. I replaced that with the ecs kit and the car purred for about 200 miles without a problem. Now it is back to square one because it is acting up again. I cleaned the throttle body when I did the PCV kit.

The car has a few codes as follows, the inefficiency codes have been there for about 10,000 miles so I do not think they are the problem but who knows. I am more concerned about the low fuel code and the fuel trim code.

17535 - Fuel Trim; Bank 1 (Mult): System too Rich
17537 - Fuel Trim; Bank 2 (Mult): System too Rich
17658: Fuel level to low
17549: Load Calculation Cross Check Range/Performance
16816 - Main Catalyst of Bank 2 Efficiency

That's all I've got any ideas? I was about to throw a fuel pump in, but I don't want to continue throwing money at it before asking.

 

Clean the mass air sensor for one (fuel trim and load calculation faults can occur because of it). Be sure you clean the connector that plugs into it too. Check for vacuum leaks, and do a throttle body adaptation as well (search feature will show you how to do it).

 

Now this problem is intermittent, as in it doesn't happen all the time sometimes it idles fine for 20 minutes then I start driving stops fine at stop signs and lights no idle problems then randomly it wants to stall at a stop. Now will the TBA have any affect on that? Can a dirty MAF be an intermittent problem?

Sorry for being a skeptic I just want to make sure I'm covering all my bases.

 

I cleaned the MAF, including the connector. Also, I replaced a bunch of vacuum lines that looked like junk. Still no change. I am stumped here.

 

Just an update I discovered the problem. A broken wire. The MAF has a broken wire and when you jiggle it the car stalls. Thanks for what help I received.