This is a quirk of the EDS computer on the 86/87 cars. The redesigned (incompatible with 86/87) version in the 90/91 cars doesn't do this (it has it's own quirks). I had good success replacing the capacitors in my EDS computer on my '86 SDL and greatly reducing the irritating high idle issue. I have a thread on this forum somewhere where I documented it.
The other option is to unplug the EDS solenoid on the back of the injection pump and use the mechanical idle adjustment to set the idle speed to ~650 RPM.
|