So my 2001 Audi A4 (1.8 Turbo) is running weird. It runs great and fine when you first start it up and gets going. No problem & no bogging. After driving for about 10 minutes or so on the highway it starts to bog and doesn't stop until I turn the car off for about 5 minutes, then it runs fine again.

I took it into the Audi dealership and had them do a diagnostics on it. Came back with a few crack crank case hoses, few crack vacuum hoses, due for a timing belt, and a evap purge value needed and they also said the "Mass Air Flow Senior" may be bad but they wouldn't know til all the cracked hoses were replaced.

So I took it home. Did the timing belt, replaced ALL the vacuum lines, all the crank case hoses, a turbo crank hose (even tho they said it was fine), air filter, and an oil change.

CAR STILL BOGS after driving it for about 10 minutes or so. I went back to Audi and they wanted another $150 to tell me if the "Mass Air Flow Senior" was junk or not. Even tho they originally told me I wouldn't need to pay again as long as I bought the parts through them (which I did). Told them sorry I'm out of money.

So now I need help from else where. Anyone have any idea's if it's the "Mass Air Flow Senior" or if something else would do this? I just don't get it anymore. I don't want to spend the money replacing the MAFS to find out it still bogs. I just don't understand why it only bogs after being ran for about 10 minutes or so.

Any help or opinions is welcome. Thanks guys!

 

I would check all the vacuum lines again and also the vacuum check valves. Blow through them to see if they leak internally. Make sure you diverter valve is good also. You might have a blocked crankcase hose. Hope that helps.