Thread: disco 1 likes to stall!

So Adnic how did it go?

I just cleaned my throttle butterfly and AFM and just discovered that my coolant temp sender is open circuit at operating temp.

Seems to be idling better but have only done one quick drive to Supercheap.

The stepper is triggered by a number of external sensors.
1 cold start, ie when the temp sensor is above a certain value.Maybe 3or 4 steps at first, reducing as temp increases. You can experience this easily, as the steps are quite pronounced.
2 VSS when the vehicle is moving.This is why it slows on stopping. Maybe 1 step
3 Aircon compressor switch. Maybe 1 step
4 TPS , when it falls to minimum value, the stepper also looks at the RPM (from coil output) and tries to stabilise at preset rpm, ie about 700-750 RPM in neutral, which is about 550 in drive. Probably 1 step at a time. That is why if the base idle is too low it will stall.There is no harm in increasing the base idle to say 600RPM as this helps to reduce stall.
I am pretty sure that there are 4 "steps" and the stepper will do them in combination.EG aircon on=1 step, vehicle moving =1 step, so combination moving plus aircon =2 steps.
Later injections have infinitely variable motors(IAC valve) with a much larger effect.

With regard to your problem, I would be looking at the gas conversion.If you are using the stepper on idle , I guess you have vapour injection? Maybe the mixture is fluctuating because of freezing or inadequate heating of the gas. Do you have an 88C thermostat?

I cannot refer back to your original posting, but have you looked at your centrifigal advance? A sticking advance will do this ie hold revs up on idle sometimes.

Also try increasing the base idle. You know that you have to block both ends of the pipe from throttle to stepper when doing this.
Regards Philip A