Thread: Hi idle on 93 Disco 3.5 V8

See if the vacuum capsule on the distributor is functioning. (ie suck on the vac advance hose and the distributor rotor / vac advance plate should move). If the vac capsule has failed, that can affect idle ( Happened to a 91 disco I had). If it is that, you can replace it without removing the distributor.

Does the rotor shaft spring back when you move it manually? Ie the springs are attached.

It sounds to me like it is NOT together properly and the timing is moving all over the place.

Look at the front pulley with a timing light and you will see what the timing is doing.

Regard sPhilip A

the springs are definetly on and it spring's back ok, how easily should the vac advance move

suck on the vac advance pipe and see if the shaft moves. you shouldnt loose suction, if you do the diaphram is rooted.

if the dizzy is all fine, and probably is, have a look at the IAC valve. it controlls the idle speed. also with it running spray and aerosol, ie wd40, around the intake manifold, the IAC valve, and the intake hose, if the engine rev's up you have an air leak you need to fix.

one thing to remember also is the timing marks may show correct with a timing light, but take the chain stretch into account and worn lifters bla bla and it could be out enough to be too advanced, this was the case with my old 3.5.
i used the flog it till it pings method of tuning, never touched after that. i cant remember exactly what the degree's were but i know it was at least 8deg out.

cheers phil

will give it a go but pretty sure thier are now vaccum leaks, and it was fine until i changed the rotor which was stuck on the dizzy resulting in the top shaft being lifted and disengaging the springs. Have moved the dizzy a tooth back and a tooth forward and it still reved hi at idle, tonight i also fitted another stepper motor which still made no difference, is it possible it could be a ecu failure or something to do with the MAF.

all help will be muchly appreciated, it is annoying the crap out of me not being able to find the fault

ecu, i strongly doubt, MAF, possible...
what happens when you advance and retard the timing with the engine running?

cheers phil

Originally Posted by discowhite

ecu, i strongly doubt, MAF, possible...
what happens when you advance and retard the timing with the engine running?

cheers phil

X2 for the above ....


This all started after you pulled the Dizzy apart

1 .. Have you checked that the Vacuum advance is hooked up to the advance plate properly (internal of the Dizzy)
2 .. Pull the "vacuum advance hose" off the unit (Dizzy) // Is there a difference
3 .. Back of the Stepper unit / motor .... There is a small vacuum line ... Is it connected /// You have to feel & tuck your head right at the back of the motor to see it
4 .. Pull the plug (wires) off the stepper motor .... Does the car settle down?

It'll be something silly that has happened


Oh ... and check that your butterfly is closed and the accelerator cable is not bound open ... = high throttle & idle

Mike