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Saturday, I took my 91 Turbo to C&C. On the way there, I enjoyed a 3rd gear run with full boost. How awesome! On the way home, I was excited to hit the same stretch of road, but this time boost stopped / stumbled after .3 bar. The engine is running great and I did not notice issues at .1 or .2 bar. I thought it might be the waste gate, so I took it off and exercised it with compressed air on the bench. It seems to work fine. I'm not sure what to try next, but here are a few ideas I have that could cause this issue:
The wastegate would generate a higher boost pressure if the membrane were defective.
The most likely cause is probably that the boost pressure is blown off somewhere. So the advice is to check the entire pressure side wether there are a hose slipped off, a clamp loosened or the O-ring on the throttle valve being pushed out. The elbow hose on the suction side can also cause this, e.g. if it is attached but not fixed. A fog machine would be perfect to look for leaks.
I agree with Fritz. I would try the O Ring first. I had the same problem. It rolled. I was told to make sure it was properly lubricated before I put it back on.
Yes must grease that ring around the throttle and wiggle the intercooler carefully onto it while watching underneath. Other random thoughts could be boost pressure sensor, it's wire connectors, tightness of all the clamps, look under and behind potentially loose hoses in the pressure side, use a mirror, remove things and inspect for cracking or tears. Could something in the air from air flow meter down be collapsed or collapsing cutting off air flow before passing the turbo for pressure? There's a metal ring in upper end of the big plastic pipe that comes loose and it could be sitting in there crooked. I glued mine in place. Might want to just take the air system apart from the filter down and have a look at everything in detail, refit it all perfectly after inspecting. I also replaced all my clamps as well, could the bottom clamp on the pressure hose from turbo be loose? Mine was last week (also discovered tearing at the bottom of it, the rubber gets weaker down there from the heat).
If you have the wastegate off may as well put a new diaphragm in it, new nuts and bolts. Also recommend just replacing the throttle o ring, as well as the IC mount bushings, it installs easier too when the rubber is all new and soft.
You guys are awesome. I should have checked the hoses before jumping to conclusions. You can see from the pic that the hose clamp is off the intercooler hose. Looks like I should update the hose and clamps.
yes that hose ages and will then blow off often. Ask me how I know. New one will solve that issue. No need for crazy fancy hose clamps, fyi, just he new hose will solve the problem.
Have just fitted the same kit. Easy install. Haven't had an opportunity to test it yet, but the rest of my suspension parts are pretty tired, so I'm hoping for quite a bit of tightening up once everything is done!
To me this stuff is only useful if you are building a race car (and changing the suspension to a race car setup at the same time). Our 964Ts perform amazingly well stock and are also smooth for long road trips - why stiffen certain things up and chip away at this lovely feature of these cars. I love that my 964T works like a proper touring sports car.
I blew 20K putting Porsche's new setup in my 993 and it would be great on a track but absolutely sucks on the road. Apart from the constant kidney crunching movement, I get front wheels coming off the road in uneven surface turns which requires constant attention/correction. Gonna sell that car probably, someone else will love it.
To me this stuff is only useful if you are building a race car (and changing the suspension to a race car setup at the same time). Our 964Ts perform amazingly well stock and are also smooth for long road trips - why stiffen certain things up and chip away at this lovely feature of these cars. I love that my 964T works like a proper touring sports car.
I blew 20K putting Porsche's new setup in my 993 and it would be great on a track but absolutely sucks on the road. Apart from the constant kidney crunching movement, I get front wheels coming off the road in uneven surface turns which requires constant attention/correction. Gonna sell that car probably, someone else will love it.
New exhaust locknuts for wastegate reassembly!
someone setup your suspension wrong, it shouldn't behave like this.
07-03-2023, 08:46 AM
Turbo - Boost Problem
