Hello I am new to the site,

I am working on a 2000 audi a4 quattro 1.8t and it has had a very bad idle and misfires.

I tested the coils they seem good, also changed plugs. Cyl 4 coil was bad so I replaced it.

I disconnected the maf sensor because I had a DTC and after that it ran like new.
While I disconnected the maf sensor I plugged in my friends vag-com and under misfire it said zero for all 4.

Then right when I plugged in the maf sensor it began to run real poorly and all misfires came back on all four cylinders.

Has anyone seen a problem like this?

Please let me know.

 

Bad MAF. It's common.