Delay returning to idle

[GreenV8S]

It needs to be adjusted so it gives the right voltage with the engine off, and then not fiddled with. It is not there to adjust the mixture! Can't remember off-hand what the reference voltage is but it may well be in the bible.

[joospeed]

apk said:

I know this is an idle problem, and I will get told to check the stepper, but this has been an ongoing problem, spanning several services and dealer stepper motor cleans, so I'm going to brave it and ask.... Griff 4.3 (K) which doesn't return to idle until the car is motionless for a couple of seconds. It stays at about 1700 rpm, then drops to normal idling without any hunting. The main problem this causes is moving in slow traffic, it stays at these higher revs and drives the car without touching the throttle. Any clues where to start looking?

er, it's supposed to do that! it bleeds air into the plenum to stop the massive vacuum on deceleration from vapourising any fuel condensed on the inlet port runners .. by bleeding air into the plenum the vacuum is less, so the emmissions don't suddenly go sky high in an instant. it should return to normal tick-over once the archaic land rover lucas ecu has detected the car is stationary, all the time you're driving the stepper is pulled back a bit to bleed that air through. 1700 revs sounds a bit high, but what your car is doing is actually correct.

[apk]

joospeed - thanks for that. I was thinking it might be something like that, but my queries are, why 1700rpm (what is a more sensible figure), and why so long. Ranges from 2-6 seconds. Do I have to be absolutely stationary for it register?

Either way, it's blinking annoying. If it was around 1200-1300 for a second or two that would be fine, but because it's so high and for so long it drives the car along with no intervention.

Would lowering the base idle also lower this value?

[andy43]

My 4.3 precat does the same thing when nicely toasty warm...'they all do that sir...'. - it is annoying if you approach traffic lights in 4th and the car kind of keeps going, or idles way too high until completely stopped. Until I read the above I thought mine had a fault too

[GreenV8S]

The V8S does this occasionally and it really irritates me - but most of the time it is fine and idles at about 1200 rpm on the approach to junctions and then straight down to 950 when it stops. Similarly it sometimes decides it wants to idle at a very lumpy 400 rpm for a minute or so before getting its act together. Both problems very rare and I assume it's just the stepper motor sticking - a reminder to clean it.

[gerjo]

My Griff does the same when cold and occasionally when it's hot. Strangly enough you notice it at start up: what I do is when it starts reving at idle, I wait (a few seconds) for it to settle and then drive off. When I do this, it behaves normally when driving.

steppermotor was cleaned and everything checked; dealer puts it down to ECU