I have a 99 A4 Quattro 1.8T. Between 2000-3000 rpms there is a studder and doesn't really gain any power before 4000 rpms. Also when throttle is snapped in forward or reverse car stalls. Any ideas? It has a new throttle body,mass air,spark plugs,bov, and fuel filter. and plenty of fuel pressure.

 

Could be your throttle valve control module or my likly guess your throttle drive angle sensor. what could be happening is that your sensor contacts are worn out in that range from a lot of interstate driving. that metal wheres out and when it doesnt get a good signal the ecm doesnt know what to do

 

There was no drive by wire in 99. Does your car have a bov or a recirculation vavle for the turbo?

 

Should use a DV not BOV.

 

I am running a TurboXS H25 Bypass Valve. Car was acting ther same with factory DV. And all throttle body components replaced and adjusted.

 

brain fart sorry check the throttle position sensor. if you have an o-scope very easy to check

 

Have you adjusted the TB since all this? You may need to do a Throttle Body Adaptation.

 

Throttle body has been adapted already and TPS replaced. I'm running out of ideas

 

DV was shot on the first time then you replaced it with another problem "BOV" the Audi doesn't like that setup as the ECU rejects it like a broken limb, so all you did was replace a problem with a known problem- replace the DV

 

It is a recirculating valve. This valve is made specifically for the 1.8T.