i have a problem with a 1985 911 carrera 3.2 . when the car is started it idles ok , but if you rev the engine and let it fall back to idle it often stalls , any ideas? . not sure if it has anything to do with it but i had the brake master cyl off and with the booster un connected it ran ok (letting extra air in ?)

 

Hi Grant:

From your description I'd offer two suggestions:

1) Your Idle Stabilizer Valve on top of the intake manifold might be gunked up with oil and now sluggish. This is quite common and should be removed and then thoroughly flushed out with a spray can of carb cleaner.

2) The other issue with Carrera's are vacuum leaks. These engines tend to develop leaks at the base of the intake manifolds where they meet the heads. You might see if they are loose, but depending on the engine's mileage, it might be worth installing new gaskets.

I use that can of carb cleaner to gently spray a little bit of this at the base of the manifolds while the engine is running. If you have any vacuum leaks, the idle RPM will pick up as the cleaner is sucked in and burned.

Hopew this helps,