Hey guys,

So as I was getting ready to go to work this morning, I was sitting in my car letting it warm up, and my foot grazed the gas pedal. When it did, the car immediately stalled. So I started it back up, pressed the gas pedal, and again, it stalled....no signs of stalling before hand, just completely shuts off (like I turned the key off). It did this about 4 times. Then I was able to get the car to rev after it had warmed up a little, by barely pressing the gas pedal more and more. Once the car was warm, it seemed to be getting better, but I left it at home cause I didn't want to drive it that way.

¤ I tried my spare key (first thinking it was something with the immobilizer)
¤ I searched (what I could) for vacuum leaks, which I am planing on continuing as soon as I get home.
¤ The spark plugs are new, as of last week

Couple other notes:

¤ The last few days, the car has not revved itself in the mornings to warm up
¤ I recently got a CEL for an O2 sensor (don't remember the exact #, but I think it was P0421)

Any ideas?

 

Try doing to throttle body adaptation process. Then look at the MAF. It really could be that 02 sensor though.

 

Ok, so here's my update....

When I got home yesterday, I did the TB adaptation before I started it. It turned over quite a few times before it started the first time. After that, the car actually seemed to be running fine, except for the fact that it was idleing at 1000 rpms instead of the usual 750-800.

Then, this morning, the car didn't want to start at all. It almost started once and immediately died. I'm thinking maybe the fuel pump is on its way out....is there any way to test it?

Thanks guys!

 

Audi has a spec in ML over time. Not sure what it is. Your pretty much on the line until it craps out. Then you can jump the pump. Power and Ground to the two fat outter pins and disconnect the fuel line at the rail and put a bottle under it and see if any fuel comes out.

The O2 sensor fault is most likely due to your starting issue, So i wouldn't be concerned with that.

Usually if the TB adaptation doesn't take or theres an issue storing it, there will be a TB module fault.

But fuel pumps are very common in this model A4

 

Ok guys, one more time...

I got home last night and just for the heck of it, I went out to see if the car would start. At first it kept stalling immediately after starting. Then I tried feathering the gas pedal while starting and I got it to start and keep running as long as I was on the gas pedal. Keeping it even at like 1200 rpms would keep it running. At first, it would stall if I let it idle, but I got it started and kept it running for about a minute. After that, it seemed to be running fine.

Does that sound like it could still be the fuel pump?


Thanks guys,
Mike

 

If you're keeping your foot on the gas and holding it at a certain RPM then it sounds like you're bottle necking somewhere with the vac lines or intake system. I'd check all that first. Might also be the fuel filter.....

 

UPDATE!!!

Dude check your throttle body sensor. The car won't hold idle if it is faulty or dirty.

 

Ok, sorry for the delay, but I checked EVERYTHING I could think of. The TB (cleaned it anyway), EVERY vacuum line on the car, changed the fuel filter, and still did the same thing. So I'm in the process of changing the fuel pump and have come into an issue.

I replaced it, and I'm getting a wierd vibrating sound from the pump. It's kind of hard to describe, so I recorded it...lol...Here it is.

Anybody have any ideas?

 

I would check your crankcase breather hose. They are notorious for breaking. You have the same symptoms of what I had. Jumping RPMs and I could not locate the vacuum leak.

Car would eventually stall.

Search on the forum or online for this kit. It was a pain to locate until i brought it to a shop to locate.

 

My crankcase breather is fairly new. I replaced it not that long ago. When I could get the car running, it didn't appear to be loosing any vacuum.

Right now I'm trying to figure out why my fuel pump is making this noise