My 89 turbo II stopped boosting. Its my first rotary and I'm new to the whole turbo thing. Anyway, the turbo was working fine when I first bought the car, but now it will barely get past 2psi on the stock boost gauge. Everything on the car is stock except for a racing beat exhaust and an hks blowoff. I took the inlet duct off the turbo and stuck my finger in the turbo. The turbine spins freely and there is little shaft play. I did notice a small crack on the rubber inlet duct where it connects to the turbo, but it seems like the clamp would keep it together. Have any of you had this problem? Do I just need to replace the inlet duct?

 

A cracked TID won't cause it to not boost, but it can cause an air leak that will create a rough idle (or cause it to stall). What changed since it was boosting properly? Is the blow-off valve a new addition? It could be sticking open, which would allow pressure to vent off. There are also pressure testers available that can be used to pressurize the intake and see if pressure is retained.

 

Hey rotaryrocket88, thanks for the help. The blow off valve was on the car when I bought it. It was working fine. One day I went to drive the car and no boost. At least I know its not the TID, which I'll replace anyway. Someone told me to check out the wastegate to see if thats stuck. I looked at it and it seems fine. I can move the actuator. I'll give the blow off a closer look and see if thats causing it.

 

Ok, the problem doesn't seem to be the blow off valve. My sister's boyfriend, who is a mechanic, mentioned something about a solenoid. Since he doesn't really know anything about rotaries, I thought I'd ask around here. How would I go about checking the boost solenoid on my S5 turbo II?

 

The turbo duty solenoid couldn't be the issue. It's essentially a boost controller, and boost controllers can only increase boost levels. Your wastegate spring is ~6 psi, and the duty solenoid brings peak levels up to ~8 psi. If you still want to check it there is a procedure in the S5 FSM, which you can download/view online (see FAQ). My bet would still be a large boost leak. Check the intercooler couplers and anything along the intake tract.

 

I had this experience before, the problem was the Cat converter. It was thrashed after a few hundred miles due to the heat of the Engine. I suggest going to the muffler shop and have them take it off.

 

good advise "myfc3s". just try to run a test pipe if possible, and see if that helps. i have one on my fc, but its been on there since ive had it. idk if the stock cat is bolt on though... check and see if it is. and if it is you can easily do it yourself.

 

Idk if you have yet, but boost leak testing would be the best course to start on, Z1motorsports.com sells cheap and effective boost leak testers, I think they are some $15?

Would really do you good to check it either way, whether thats the problem or not, you might be suprised to find out where some other tiny boost leaks were that you didnt know of!