Morning Everyone,
I've looked around some on the forums & google & haven't found a good answer for this problem so I'll just ask again. I have a 1994 940 Wagon with the B230F Redblock in it. I just had the head off of the car & have replaced seals & gaskets from the head up as well as all vacuum lines. The issue I have now is a slight high idle, nothing too crazy. I've heard/read that the idle for these cars should be around 600rpm. My wagon is idling round 1100-1300rpm. When I first start the car(engine cold) it idles at 600 no problem. I notice the high idle after driving/warming the car up. Once I park it it revs up to 1200 or so. Like I said, it's not crazy high, just not right. Anyone have any suggestions? Thanks in advance.

 

Because it happens after driving but not after starting it makes me wonder

Is the throttle plate getting stuck slightly open after driving?

Is thermal expansion from the engine getting hot causing a leak in one of the gaskets, such as the manifold gasket?

Is the IAC valve getting stock after turning on and off?




Recommendations:

Clean and ensure functionality of the throttle plate
Clean and ensure functionality of the IAC valve
Spray starter fluid around the gaskets and intake, fuel injectors and so on, do the RPM's change in any way? that is likely where you leak is if applicable

 

Thanks for the tips. I will check those items out & let you know. I drove it to work yesterday to see how it would do. When I first started the car after work is revved to around 1600. Then at a stop light a few miles down the road I kicked it in Neutral to see what it would do & it was idling perfect at 600. When I got to the house & parked it, it was idling high again..

 

i have the same problem did you solve it ?

 

I believe it ended up being vacuum leaks. The new vacuum lines I put on were too large & therefore leaked unmetered air into the motor.