Thread: High revs at idle

Originally Posted by Gary S11

Thanks bee utey, I realised that but my probs not at idle, it's above 2000 rpm, the same as vogue, blip the throtle and it sits above 2000 and slowly drops to the correct base idle

Yes but you see that I said "closed throttle" i.e. your throttle plate isn't open. There is no way vacuum can pass to the vac advance unless the throttle plate is opened past the port hole above it. The idle problem is due to the ECU moving the stepper motor in the back of the plenum chamber. Either the stepper or the ECU aren't working as planned.

The only other adjustment of the idle speed is the base idle, that one that is adjusted by a 3/16 allen key from the top. It too doesn't move the throttle plate. Screwing it down will limit the maximum amount of revs the stepper can apply. It's also worth looking at the air hose to the stepper and see if it has split ends. And if someone has replaced your fumes breather plastic tee (in front of the plenum) with a home-made brass one, it's dollars to donuts they haven't fitted the correct small jet size in the small branch to vacuum (about 3mm max).

Time for an update, I installed a new stepper motor and all is good. Idle revs are a bit high at around 1000rpm but will adjust base idle speed and all will be good. Thanks for everyone's help.