1991 Audi 100 fuel delivery

Tiny
YELLOWSKI8
  • MEMBER
  • 1991 AUDI 100
  • 2.3L
  • 5 CYL
  • FWD
  • AUTOMATIC
  • 200,000 MILES
Engine is an aad, when cold engine starts runs for about five mins and shuts down have determined
that the air flow meter which controls the fuel meter distributor is lost signal shutting off fuel to engine,
engine may restart 1 or 2 time after but then shuts off completely and just cranks until it sits for a significant time and start the process all over again. It appears the problem is further up the line from where the airflow meter receives it's signal, but wherre to look? Ecu, cold start valve, throttle idle switch?
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have the same problem?
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No
Wednesday, February 26th, 2014 AT 12:08 PM

7 Replies

Tiny
KNOWLEDGE IS POWER
  • EXPERT
Im sending you this diagram, let me know if it helps. We'll go from there
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Wednesday, February 26th, 2014 AT 4:25 PM
Tiny
YELLOWSKI8
  • MEMBER
I am reviewing the drawing thanks, all my research indicates
the airflow meter is controlled by the ECU therein I believe lies
the problem, does this sound logical?
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Friday, February 28th, 2014 AT 11:36 AM
Tiny
KNOWLEDGE IS POWER
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A faulty air flow meter will cause noticeable driveability issues. Its not controlled by the ECM but rather the ECM uses the info it gets from the meter to control fuel. They work simply by varying resistance as the little door moves in against the spring. First make sure the movement is easy and fluid, then if you've got the tools, ohm the meter by slowly moving it from one end of its travel to the other. Sudden changes or lulls in the change of resistance indicate a problem.
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Saturday, March 1st, 2014 AT 7:03 AM
Tiny
YELLOWSKI8
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I was wondering about that!
I removed the AFM and on a bench with a ohm meter I registered the following: movement appears to be smooth
Closed resting position ( not tight closed but closed )
cntr and bottom contacts.1.6 +-
cntr and top contacts.5.5 +-
out to out contacts. 4.2+-

Open position:
cntr and bottom contacts.12.2 +-
cntr and top contacts. 9.5 +-
out to out contacts.4.2 +-
( All value are in ohms and appear to be fluid when I move the lever0
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Saturday, March 1st, 2014 AT 10:02 AM
Tiny
KNOWLEDGE IS POWER
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Ive looked for resistance specs for that but I don't find any in my sources. You might be able to find out if you call an audi dealer. We dont have one where I am. But I don't really see that as your problem if you've got those results. Id try this, buy some carb cleaner spray and see if the car will run on it after its heated up. That way we can determine if its a fuel control or delivery problem. It may not be fuel at all but I don't know what tools you have at your disposal. I doubt you've got a fuel pressure tester with an audi adapter, I don't. Lol. But it CAN be fixed. Patience is all that's really required. Well that, and money.
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Sunday, March 2nd, 2014 AT 2:43 AM
Tiny
YELLOWSKI8
  • MEMBER
Initially I checked for fuel pressure at filter than fuelmeter,
Plenty of pressure at both, I then disconneted acouple injjector hoses from
fuel meter, nothing. Next morning while cranking engine startted
Shut it off and fuel was coming out at disconnect hose location on fuel meter.
Connected hoses car ran for about five min shut down, started a couple
Times more untill it would not start just crank, disconnected injector lines
no fuel.
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Sunday, March 2nd, 2014 AT 8:31 AM
Tiny
KNOWLEDGE IS POWER
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It sounds like an issue with the fuel control unit itself to me. Id see how much one is and consider replacing it. I hate guessing at these things but tits hard at this point this far away
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Sunday, March 2nd, 2014 AT 3:23 PM

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