Hello, How stable should the idle engine RPM reading be on the 355? 1000RPM +/-? is it normal to have a 50 to 100 RPM fluctuation in the tachometer? Thanks, 355Blue
25 to 50 rpm probably what mine does on occaision...100 might be a problem. I had some fluctuation once, and noticed if I fiddled with the MAF sensor connection or cleaned it, then the idle would be stable for several days or weeks. I later had the local dealer replace the female pins on the MAF connector and that fixed it. Does it coincide with the radiator fans coming on? That is, does the idle drop as the fans come on? If you have idle drop with the fans coming on, then you will need to replace both fans: http://www.ferrarichat.com/forum/showthread.php?t=284513&highlight=355+fans
I would think that the Idle Air Control motor, if working correctly, should compensate for the drop in rpm caused by the heavy electrical load and bring you back to normal idle speed.
You'd think, but it has been repeatedly shown not to respond that quickly. Owners have literally had the car almost stall. I have never experienced it myself, but several have described it here on this forum and corrected it by installing new fans.
