I have a 87 turbo II with a motor that runs great and no current mechanical problems other than my strange idle. The car has no air bypass solenoid valve because i always let it warm up plenty. When I start the car when it is cold, it will typically idle at 1500 rpm - 2000 rpm, and will continue to do so for the 25 min drive to work and stay around 1400 rpm when turned off, no matter if I am on it the whole way to work or not. If I were to start the car 5 mins after, it is completely warmed, it will idle at a perfect 750 rpm, and continue to idle there. I assume it is something to do with one of the many valves but not quite sure where to start looking, I looked throught the workshop manual but found nothing in troubleshooting relating to this. If some one could point me in the right direction that would be great.

Also my stock coolant temp sensor never goes above 1/3 of the gauge when warmed up, I wonder if it is a partial open t-stat problem or if the gauges on
these models just peak operating temp display there.

thanks

 

Two items come to mind. First and foremost is sticking linkage on the water thermo wax, fast idle came etc. The second is a BAC that isn't fully closing on it's open/shut strokes. Not that likely, but something that can be looked at if the water thermo wax unit does not solve the problem.

In short, the cam and rollpin not fully seperating once the engine water temp is fully hot. OR, come to think of it, someone might have removed the water hoses on the bottom and top of the throttle body, and the thermowax is only extending when the heat of the engine passed thru the metal body of the throttle body to the thermowax. Then its piston would extend and seperate the fast idle cam from the rollpin. But would take quite a while for this to happen. See FUEL AND EMISSIONS section of the FSM for the fast idle cam/water thermowax adjustment etc.

Also, the rollpin has a SLEEVE on it that should spin on its shaft. It might be frozen up making the seperation of the cam and rollpin more difficult.

 

thanks looks like a good place to start.

 

I'm having the same problem. Did Hailers ideas work?