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Car started idling real rough..

Car: Audi, A4, 2004     -    Back to Fix-It    -    Audi Repair Manuals

Q.So on Friday I was going to dinner and the car started idling real rough, when I pushed in the clutch it would rev up to like 3k and then slowly come back down.
Changed out the coilpacks...nope, checked all vaccum lines and boost leak test...nope, removed all vacuum lines and check valves, what not.
The only throttle response I'm getting is if I press on the gas when I start it and it will rev up accordingly but after that...nothing no throttle response. After it dies it smells real rich and it almost sounds like it's starving for gas. It's only holding about -10hg instead of -20. Of course it's not throwing any codes...I'm at a loss here.

I already checked/done: I've pulled the codes...nothing.
Vacuum/boost leak test...nothing.

Answer Your symptoms would be consistent with a failed Mass Air Flow (MAF) sensor. It is the sensor that is at the outlet of the air filter box connected to the tube that leads to the turbocharger. To verify this condition, you would need to use a VW/Audi capable scanner that can do more than retrieve and erase Diagnostic Trouble Codes (DTCs), but could also look at various data streams and see the actual amount of air being reported in correlation with engine speed and load to determine if the amount is correct. You would also want to look at the "fuel trim" measuring block and determine the given trim compensation at idle (Addi.. >> login for more

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