456 idle

when i fire up (cold or hot engine) it sometimes runs on a very high idle
(up to 2000-2500 rpm) for about five minutes, then it settles down
again to normal and stays there. i fire up, the idle is about at 1500 rpm
i then touch the accelerator very slightly and it goes up to about 2000 rpm and stays more or less there for about 5 to 8 minutes...

anybody an idea what's the problem? the accelerator-pedal isnt stuck.

 

actually, I've had the opposite lately: low to almost killed idle on cold start. thinking the sensors on a slide...taking it in for oil change this week [get the Mondial out of shop---wax on, was off] so will ask Ferrari about it too. Have seen many threads on this idle issue....

ALSO, been getting a sort of lurch on cold idle...but, expect that's related...gone on warmup, could be injectors[?] etc.

 

The "temporary" high idle could be a sticking Bypass Air Solenoid. Idle speed is regulated by bypassing air around the throttle plates. I have seen this on other cars I have owned.

I am starting to wonder if my cold, low-idle problem is being caused by the same.

Hope this helps,

Mark

 

and would that bypass also stick when the car is hot? for example when i stop to refuel and start the engine again i often have this problem again for some min.
also, the first time it occurred was when i restarted the engine after having stalled in reverse. i cant see how this could be related, but maybe im wrong.

anyway thank you all for your help!

 

I think the BPA solenoid could stick at any position at any time. I recall with my old Escort (don't laugh) that it would stick open so that the engine would have a fast idle after driving for a while. I believe the engine strategy was to open the BPA solenoid up during cruise so that when the throttle was closed the BPA solenoid could be used sort of as a dashpot. This would return the car to idle slowly instead of slamming the throttle shut. I assume this would help with emissions. The BPA solenoids would gum up over time and stick. I cleaned mine with Gumout and it cleared up the problem. (Though there was a warning sticker on the solenoid not to use cleaners on it as it would remove some coating on it.)

Note this was with a 4 cylinder Escort that has one throttle body, not a 12 cylinder Ferrari with two throttle bodies. I don't know how the engine would react if the BPA solenoid on one half the engine was stuck open while the other one was working properly.