Please diagnose my CIS problem

[fireant911]

My car starts up and runs fine cold. If you turn it off and immediately start it again, it runs fine (cold, warm, or hot). The problem is if the car it up to normal operating temperature and you shut it off for greater than 30 seconds - the idle majorly hunts to the point where the engine dies unless you provide some throttle. During this time the car bucks but as long as you maintain some throttle the car can be driven. After driving for only a couple of minutes everything settles down and the idle is dead on 950 rpm's with no idle hunting and no bucking.

I purchased the Bosch Fuel Injection & Engine Management book by Charles Probst and How To Tune & Modify Bosch Fuel Injection by Ben Watson in order to identify and correct this problem to no avail. The Bentley manual does not address my symptoms either. My O2 sensor is connected and the Lambda appears to be functioning fine. Please help me fix this annoying problem.

[jester911]

Daryl,

It is possible this is not an injection problem. I had a somewhat similar problem and found the distributor cap to be in bad shape.

Replaced the cap and rotor and no more problem.

[hoosierdaddy]

It sounds like your car is running to rich . You need a long 3mm allen wrench to adjust the mixture srew . Our host sells them and its simple process .

Jim

[john walker's workshop]

unplug the oxygen sensor and set the CO to about 3.5%. leave the sensor disconnected. see if that helps.

[unclebilly]

I'd suggest you clean up your air vane with carb cleaner and be sure it moves freely. My neighbor, who it a mechanic and has fixed plenty of non Porsch CIS injection systems keeps telling me to put a liter of oil in my fuel at the next fill up.

[Hladun]

1. Check the CIS pressures using the proper test gauge, then
2. Set the CO using a proper gauge (don't fool around with this setting, it's very sensitive), then
3. If you're still having a problem, post your results so we can help.