Hi Ferrari Folk. I am having problems trying to reduce the idle speed on my 348. The butterflies are both up agains the stops. The linkages are nicely synchronised, and the air bypass screws are turned down as far as they will go, I have also cleaned out the idle control valves, but the idle speed is still too high. Can anyone give me a hint on how to reduce the idle speed. Many thanks Harry
Thanks for the reply. I have held a tube to my ear and hunted around for a hissing but cant find anything to indicate a vacuum leak, where abouts should I be looking ?
have you tried cleaning out the idle control valves? Can just be a case of getting in there with a load of MAF cleaner and giving the valve a good cleaning out. Helped mine settle down. I'd do the same with the MAFs while you're in there, see if that helps.
On motorcycles, tight valve clearances can cause high idle when warm. Probably not the cause here, but one more possibility, I suppose.
I would start first with anything that is plugged into the upper plenum then go from there. Try to use logic as to where the greatest wear or damage may occur - heat, chaffing, something like that. Most of the time the leak is close to the end of the vacuum pipe lead where the hose connects.
What are you expecting the idle to be? These cars idle higher than many, my Camaro and Subaru idle at 500, the 355 idles at just under 1,000.
Try doing a hard reset of the Motronic ECUs. After the car has sat all night, disconnect the battery for about 15-30 seconds, reconnect, start the car and let it idle, with all accessories turned of, until the cooling fans kick on. My car idles right at 1000rpm btw. One more thing. If the ecu reset doesn't do it, try swapping the throttle position sensors from side to side and see what that does. If the tps goes bad the Motronic has no idea how open or closed the throttle bodies are, or aren't, it will run erratically.
