Hi,

new to the forum.

I've got a 1998 A4 1.8t
136k miles

Symptoms:
Loss of power during a recent trip. Going up a steep grade the car was really struggling ~ 40 mph. Previously car easily did 75 mph up same hill.
Did a VAG and came up with codes for N75, charge pressure and throttle body.

17956 - Boost Pressure Regulation Valve (N75): Open Circuit
P1548 - 35-10 - - - Intermittent
17965
17967
17973

So far I have changed Diverter Valve as it did not hold vacuum and changed N75.
Current Error code is only for N75 ( even though part is new).
Car idles ok, but stumbles on way back to idle if given some throttle.

I have checked the wastegate actuator with a bicycle pump. The rod moves and returns to position. I do not think it is actuating upon WOT.
I removed the intake tube to the turbo and the vanes spin freely (not seized).

My VAG does not seem to show boost pressure using MB 115. I am thinking it is either the turbo wastegate flap is gone/blown turbo or the ECU is bad.

I need some help figuring out how to test the boost and where to look next.
Thanks

Jeff

 

Do you have a boost gauge? What's it reading? Try going straight from turbo to wg and see if powers there. Also check ic plumbing. Might have a tear in one side. I'd have tO guess maybe hotside

 

No boost gauge - car is totally stock. I guess I cannot get a boost pressure reading from VAG for a 1998 ??

"Try going straight from turbo to wg and see if powers there. "
Not sure what you mean...Please elaborate.

"Also check ic plumbing. Might have a tear in one side. I'd have tO guess maybe hotside. "
You mean the intercooler plumbing? I will check. Any specific areas?

Thanks,

Jeff

 

Yes. Just check all the rubber boots. Might even check the vac hoses. Get a boost gauge.