Thread: 930 Cutting out
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Originally Posted by beepbeep View Post
There is a hose going from intercooler to lower part of wastegate bell. Detach this line and blow air trough it with your mouth. If lot's of air is flowing trough, you have ruptured membrane. (observe: some air might escape trough valve stem, nut not much).

Other way to do this is to connect a short piece of rubber hose to vent pipe from the top of the wastegate. This short piece of brass tubing is not connected to anything. If you can blow trough this pipe, then membrane is ruptured.
beepbeep, car just arrived back from Germany (no more autobahn ) and I attempted your test. I blew through the hose from the intercooler to the wastegate. It seemed like air did go through. I didn't have any pressure sensitive tools, but about a mouthfull of air would pass through after about 3-4 seconds if I really put pressure on it.

After driving more I have noticed several things. The dashboard in the face doesn't come when I'm pushing the accelerator any more; only when I let up on the accelerator (even if I just think about it), this is usually when the turbo is at max boost. It's almost as if the fuel completely shuts off right when I pull off the accelerator, and I completely loose power and speed MUCH faster than normal.

I believe there is a fueling issue. I say this because I have a second problem. It is most noticeable when I'm accelerating from a stand still. It's a sudden cut out. Seems like it cuts out and then comes back a split second later. It seems like the engine almost stalls several times until it comes up to 3000 RPM. This is more pronounced AFTER the car has warmed up (if I'm driving around town and make several stops at different places). Could this signify a WUR issue?

I'm considering studying up on the CIS system, what would you guys recommend for reading? I've got the 101 projects and the accompanying Modifying Porsche 911 Engines, but neither really got into the weeds on the CIS system. Is there anything I can read that would help me understand the early turbo engine as a whole (fuel, turbo, electrical)?

Thanks for your help guys.
'77 930 with a few mods to include intercooler and K27 turbocharger . . . who needs anything else?
Old 07-19-2009, 07:24 PM
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