I have 2003 Audi A6 with about 60k miles. First off, my check engine light has been on and off for a few years. I was told by the dealership a couple of years ago it was probably a bad sensor. It will stay on for a few days/weeks, then go off for a while, then come back, etc. So I am not sure if it has anything to do with my current issue.

My car basically died today when I was driving at a low speed. It starts up fine, but then it eventually would die, usually after trying to drive or revving up the engine. But it doesn't always die, I am able to rev up the engine while in park, but the weird thing is that when in park, and my foot not even on the gas, it would be revving itself up. I don't know anything about cars. Two lights on the dash came on: the "Generator" light which looks like a battery, and also my "Electronic Stabilization Program (ESP)" light, which is a triangle with an exclamation point in it and a circle around the triangle.

I had the car towed to a mechanic. Once we got there the car seemed like it would drive, but again, it was revving itself up and the lights were still on. I am sure it would have eventually stalled/died if I tried to drive it anywhere.

Any ideas? The guy who towed it thought maybe an oxygen sensor. Perhaps that, or a vacuum leak? I don't know cars so no idea what would cause the car to rev itself up and eventually die.

 

I have the same exact problem. I stopped by audi today and after they took a look at it and ran the codes they told me that it's a vacuum leak.

Does anyone know of a good way to find the leak?

 

Yeah it's definitely a mixture problem. So you should be looking at the MAF and vacuum leaks. Then move your way towards oxygen sensors.

 

i would check the maf sensor first like nm3210 said and a good solution to vacuum leaks is using soap water u will see where it gets sucked in, usually bubbles will form, i use soap water to find boost leaks so it should also work for ur vacuum leak, but what u can do to find out if its the maf sensor is just disconnect it and basically ur car runs off a backup program ( note that the first time u turn it on with the maf disconnected it will most likely turn off but should stay on the second or 3rd time because the ecu switches over) or u can disconnect it while the car is on and if it stops doing the rpm issue then u have ur solution

 

The first thing to do is get the codes for the lights and begin diagnosis from there. It does sound like an air leak between the MAF and the throttle body. Check the ducting for leaks.

 

I just talked to the mechanic. They are doing a few other checks, but they seem fairly confident that my issue is that BOTH my cam sensor AND my MAF sensor are both shot. My check engine light has been on for a few years and I knew it involved the cam sensor, so he said that was probably a warning. But since both sensors are gone it is causing the car's computer to go haywire. So I will probably have to get both fixed, they quotes me around $50 for the cam sensor, like $220 for the MAF sensor, and a couple of hours of labor. Seem reasonable?

 

Unplugging the maf didn't change anything for me, but i can definitely hear a vacuum leak.
Also if I remove the engine oil cap I can hear the vacuum leak much louder somewhere behind the engine.

 

Smoke machine generates smoke to test on vacuum leak ...

 

interesting... I never thought of using that

 

"smoke machine vacuum leak" and a bunch come up. ..