YarnMaster
SupporterHi Guys,
the idle speed is stepper motor driven on a '92 model...... Does anyone know why the car will suddenly decide about 450rpm is a perfectly fine idle speed .... I'd prefer about 800rpm myself! The stepper motor is working fine (it'll cycle on the stepper before it settles down if it almost stalls).
seeya,
Shane L.
Proper cars--
'92 Range Rover 3.8V8 ... 5spd manual
'85 Series II CX2500 GTi Turbo I :burnrubber:
'63 ID19 x 2 :wheelchair:
'72 DS21 ie 5spd pallas
Modern Junk:
'07 Poogoe 407 HDi 6spd manual :zzz:
'11 Poogoe RCZ HDI 6spd manual
Swaggie
SubscriberWell your kerb idle should be set at about 550 anyway.
It sounds like the stepper is sticking shut.
Have you cleaned around the throttle body and blade?
you also should clean the stepper seat and cone on the shaft. You should not pull on the shaft to try to clean inside.
Aworking stepper should hold revs up to 1100 as you stop then drop to 650 or so.
Have you considered that it could be a cylinder dropping out?
regards PhilipA
Master
SubscriberMine was similarly idling slow until recently (91 so same as yours probably). Two main things I did after cleaning the stepper motor pin and seat was check for vacuum leaks - found the fat line running to the stepper motor looked fine but upon taking it off was a bit cracked underneath. The other major difference made was cleaning the oil breather line at the T, where it reduces and goes to the plenum - the brass insert was totally blocked, and the same breather line where the end goes into the earlier part of the plenum before the throttle butterfly - the latter the hose was open, but the internal tube in the housing was totally choked up with carbon. Since then the idle has been really strong and stable. The crankcase really needs to breathe.
YarnMaster
SupporterThanks Guys,
well that sounds simple enough (I was concerned it was just an adjustment somewhere0 .... but this sounds a lot simpler
seeya
Shane L.
Proper cars--
'92 Range Rover 3.8V8 ... 5spd manual
'85 Series II CX2500 GTi Turbo I :burnrubber:
'63 ID19 x 2 :wheelchair:
'72 DS21 ie 5spd pallas
Modern Junk:
'07 Poogoe 407 HDi 6spd manual :zzz:
'11 Poogoe RCZ HDI 6spd manual
Master
Really good advice above.
A couple more options if all above doesn’t work and the engine is in good shape.
There are stepper motors and slepper motas,I have a small collection and all have different characteristics on start up revs and idle behaviour.
F4CC317F-2538-43D3-B788-58C5CFF8501F.jpg
As can be seen in the picture of a couple of mine.
The aftermarket (right)versions tend to have a longer spindle and as such at fully open position aka on start up it sits further out thereby slightly blocking the idle control airway.
No big deal,in this case you may only get a start up rev flare to 1000 vs the normal 1200-1500 but then it should modulate closed to give a 700rpm ish stable idle.
You can alter its behaviour,to some degree, by using a packing washer on the thread,this effectively pulls the pintle back further clearing more airway,and slightly increasing initial revs.
This in itself won’t necessarily alter your warm engine idle speed as normal operation should have it ‘step’ closed to 700 rpm warm.
A quick google search on setting base idle may be your next step if the idle remains low.
In essence you’re altering the amount of air travelling through the idle control valve ,by using a 3/16 Allen key to increase or restrict how much air gets to the plenum via the stepper motor.
4959107A-1683-46B1-8B46-A6CA48F1689F.jpg
Hopefully these steps should solve your low idle,failing this the next thing to look at is whether your throttle position sensor TPS is in range(voltmeter)and your Road speed sensor is working if it stalls out coming to a stop.
Top Tip
Genuine stepper motors are high cost items if you can find one.
Aftermarket suspect versions are a lucky dip often appearing in a green box.
Many years ago I stumbled on a reference to an AC Delco stepper motor to fit Range Rover classics,they share a part number with some American GM motors.
These are made in Mexico which is correct,stamping numbers are the same and are exactly the same as the Land Rover genuine version at 1/4 the price(used to be 24usd)a quick search of this ac delco number 217-437 or the GM# 25527077 ,eBay or similar should find them.
Buy Two👍
Pick the Land Rover one?
CAB4FC1B-0547-4654-B470-4FE848912852.jpg
8EEA7294-5A6A-44AA-A5BD-A1A5ABBA0D72.jpg
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