911SC idle issues

[ckakoliris]

Hey Everyone!
I have a 3.0 911 sc.
Motor was rebuild 10 years ago.
I purchased the car recently and it drive fine, although idled a bit low... The man i purchased it form didn't drive it often, so when i bought it i checked all hoses etc for wearing/ fraying.
I found the hose from the vacuum advance on the distributor to be frayed and was leaking air. I cut the tip off and stuck it back on.

Ever since, the car doesn't start on first turn, and idles too high (about 1100 warm)
The rpm hang for a while at about 1500 before they come down too (when you give it a rev).

I have checked all fuel pressures
cold = 1.5 bar
hot= 3.5 bar
system= 6 bar

Any ideas?
Could it easy as timing again? is there more advanced? i don't know exactly how it works


Any help appreciated in advance!
Cheers chris

[boyt911sc]

Chris,

What year is your car? And CIS? What is your cold engine RPM? How long does it take to stabilize and drop down (idle speed)? Does it start at low RPM and then goes up and finally settle down or just the opposite? Does the idle speed screw by the throttle body could make the idle speed change? At this stage, whatever you do, please do not tinker or adjust the mixture screw. You'll make a bad situation worst. Keep us posted.

Tony

[Targalid]

My guess is that since you changed the distributor by repairing an air leak that you should start with ignition timing. Check that first. Get a timing light and see where the timing marks are at idle and at 4000 rpm. Probably the previous owner did not diagnose the air leak and compensated by moving the distributor.