Hi Group:

Our '94 850 Turbo has developed the following problems. Idle speed is sometimes erratic, and sometimes is as high as 3-4K rpm's. If I drop the car into neutral while driving, occasionally the engine speed just doesn't drop down to normal idle speed, and of course, this can be felt as the car doesn't slow down when the throttle is released. This is not a problem relating to either the throttle cable or butterly sticking, and while the idle speed is high, if the engine is turned off and then restarted, idle speed is reset to normal. This problem is highly intermittent, but also when the car is initially started, occcasionally the idle speed revs and drops several times before settling down to normal, instead of just that one normal increase and drop. There is also sometimes an initial stumble off idle speed when th ethrottle is quickly depressed, but again, that seems to be highly intermittent.

So, what sort of issue am I looking at here? Is there and idle solenoid or air bleed valve I should investigate? Several of the small vac hoses have been replaced over the years, and they all seem intact, but I haven't yet checked the large air hoses connected the AFM and throttle body.

Thanks for any advice you may be able to offer.

Regards,

Dean

Did you ever clean the throttle body? I would start there and check for any codes. Cleaning out the throttle body as a diy should take around 2 hours. The throttle plate could get gummed up and give irregular idles.

The throttle body appeared fairly clean, and as I had suspected there wasn't any binding or other trouble there. But as it turned out, the idle air control solenoid was semi-seized. After a good internal soaking with carb cleaner, the piston moves freely now, and the problems with idle speed and roughness have resolved. The top hose on the solenoid also wasn't clamped very tightly to the far end, and there was likely an air leak there, too.

Dean