3.0 motor idle problems and miss fire issues
 

aloha ...just got the 3.0 motor back in my 82 911sc....a new re-built fuel distributor...injectors are clean and working properly... cold stat valve ( after 5 replacements ) is working properly.... here is the question.... if a proper fuel ratio on the fuel distributor and proper timing st the distributor the car idle is racing around 2300 rpm at start up....so bring the idle down we had to lean out the fuel distributor and re-tard the timing.... so when we start motor it will just idle..... any throttle added it pops due to wrong timing and lack of gas... ( leaned out ).. the symptons i assumed were a air leak... or ... vacome leak somewhere .....we ran a series of test with accetalean gas all aroung the motor.... no change in the idle except at the air sensory plate which made the idle increase.... my question is....are there different areas i should be looking at for a vacume or air leak ??? if i have proper fuel adjustment and correct timing the motor is far too high of idle ... however ...the motor just screams with power and is calling me to go for a rocket ride.... any and all ideas are appreciated.... it has been one year and i still haven't done a test ride on my car..... many thanks... michael 808-346-5493...car has 77k original miles and plates are still in storage for 21 years ....

Why not just turn down the idle scew? Why did you you have to lean out the fuel and retard the timing to get the idle down?

Check:

Intake gaskets
Rubber intake sleeves
Airbox leak? Pop- Off Valve installed correctly?

What happens when you remove the oil cap, does the idle drop? If there is no change, then it is likely a vacuum leak, or it could just be that your idle is to high to make a diifference.

aloha ...we did turn the idle screw down..it wasn't enough to drop the rpms to 1000... i am still trying to get my mechanic ( on different island ) to reply as i have moved from oahu back to kauai... i got to get tjhis car running right to ship it to the mainland....and drive it...as it is too small island here with limited open road...

What are your fuel pressures for system, cold, and warm running? Is your AAR system in tact and leak free? The piping or rubber pieces for the cold start supplemental air could have a big leak in it.
One way to test it is to remove the hose at the fitting by the CSV and start the car, idle should be high (2000 rpm). Then slowly close off the hole at the base of the intake and the idle should drop. If that works, you've found the source of unmetered air.

Disconnect the throttle linkage and try adjusting the idle screw again.

vacuum advance sticking is always possible. How did you set the timing?

This makes sense and removes a potential variable.

If the idle screw is all the way in the engine should be barely spinning or die. Otherwise vacuum leak/false air.

Did you try some of the ideas offered? e.g., remove the oil cap?

Make sure you vac lines on the cruise control cannister are tight.One line also goes to the brake booster.
I had an engine that started /ran perfect. after the cruise cannister was taken off (sold) the two lines were just hanging there.
car started but not instantly and then reved at +2000RPM and popped when cold under light accel pressure.

As you can tell by the multiple possible solutions, you really need to confirm the proper functionality of each sub system attached to the CIS.