[Supras] Help! Idle cutoff cycle

[berniek at technicaldevelop.com]

Don, Joe, Bob and and group:

    I wrote before about a hunting idle condition in a '91 turbo between 800 and 100 RPM.  I have not had the time to dig into it more yet, but it appears to be the ISc, but no codes are set.  I was going to manually "throttle" feed to the ISC from the accordian hose by inserting a piece of soft Tygon tubing in series with the tubiing to the ISC and then pinching it with pliers as a test.  After tubing insertion, the flow resistance was enough to bring the hot idle down to about 1000 RPM.  It does droop when the A/C or lights are turned on, so apparently the ISC is not working.  But the mystery is that no codes are set.  

    Anyone have any ideas?  I'm going to try to get through NJ inspection on Thursday with it as it is.  There are hints of a BHG:  Misfire after startup and pushing water out of the radiator.  But I intended to change the HG next week any way.  No sign of antifreeze in the oil.

        BernieK