3.9EFI - Idling too high

[TechnoTurkey]

Hi, sorry about the multitude of questions from me at the moment, just trying to get to grips with a few minor bits and bobs that need doing on the Rangy before I have it 'just right'!

It is a 3.9 EFI Auto and seems to be idling too fast, which has the knock on effect being an auto that it 'runs away' a little bit.  Idles at over 1K and goes up to 2k sometimes, how can I get this back to how it should be, do I need to give the stepper motor a clean?

Thanks

[DoubleTop]

worth having a look at the mass air flow meter possibly.

DT.

[Poprivit-RRC]

I have a problem like this but not as high. i would be interested to know how you get on.

[Bowie]

Clean the 'extra air' stepper motor out that's on the back of the plenum, they gum up, pretty common.

Also check ALL hoses ofr air leaks, including the vacuum advance etc.

[dod51e]

You could try adjusting the idle valve located in the plenum chamber, far-side near to throttle linkage.  Also check that someone hasn't added mass to the underside of the trottle stop or linkage (where the linkage meets the plenum chamber as there is an adjustment there too.  If this is correct and the airmixture is correct then it may be worth checking the Lambda (oxygen) sensor if you have one.  Air-mass meter another option.  There is no adjustment on these units so if you think it may be faulty try substituting one that you know works from another RR of same age.

Hope this helps.

Mark

[Poprivit-RRC]

Mine was due to the last owner taking the air idle valve off and not doing it up very well  :roll:

cleaned the surface and used a little alu sealer nice steady idle now :)

[Rossko]

A common mystery air leak is in the breather pipework; there's a plastic tee-piece in the hoses at front left of plenum that goes brittle from the crankcase fumes and cracks.

cheers, Ross K

[TechnoTurkey]

I was attempting to park a caravan yesterday (not very good at it yet, but practise makes perfect) and when switching the box between reverse, drive and park in any order it would stall a few times with the rev's dropping too low.

I'm going to have a good go at the sensors and check for air leaks tomorrow and see what comes up.

[Rossko]

Ah, now that may be a clue ...   the EFi should raise the idle speed slightly when gear moved out of P/N to prevent that happening.   Sounds like it might be doing it sometimes or at wrong times, have a good look at the gearlever switch and it's adjustment.

cheers, Ross K

[Reggieroo]

Hi, sorry about the multitude of questions from me at the moment, just trying to get to grips with a few minor bits and bobs that need doing on the Rangy before I have it 'just right'!



Thanks

Don't worry, you'll be asking a multitude of questions the whole time you own a classic................lol
I'm still asking them now & still have a few minor bits & bobs that need doing. One of the jobs I never fixed was the high idle problem with mine, then loads of other stuff needed doing & that job went to the bottom of the pile.

[TechnoTurkey]

Well, so far I've removed the bypass solenoid and given it a good clean, seems a little better now but still drops when I put it into gear and rises in park, will have a play with the wiring by the gear selector at some point!

[Range Rover Blues]

Does it start in gear?

[TechnoTurkey]

No, it won't start in gear.

[Range Rover Blues]

Then I'd suggest that you check the wiring to the engine ECU, particularly the input from the gearbox.