Hi all...I've got an annoying problem with my LR Discovery '97 (3.9 V8 auto). The car runs pretty well as I drive along however if I stop thecarand go toidle speed (in drive or reverse mostly), the car spends a few seconds revving all over the place until it settles.

If I am in park, drive or neutral and switch to reverse, revs go very low and cause the engine to stall (it also causes a clunk sound from the transmission). If I switch to drive, revs go very low but the engine usually stays on. If I am stopped on drive, the revs get a bit bumpy.

I have spoken with my mechanic about it and he thinks that the fuel mixture is running too rich. He has suggested that he checks for air leaks (esp. around the mainfold area). Everything else he checked seems to be ok.

Anyone has any ideas what could be causing this? Thanks.

P.S. I have had the transmission serviced to eliminate the possibility that the clunking sound was being caused by a fault in the transmission but everything checked out ok. I am told that the clunk sound happens because the car revs too high when I put it in reverse.

 

I would check all of you vacuum lines first. They are a cheap replacement. Does it smoke? (black) Is you check engine light on? I hear that when the light is on, the engine defaults to a rich mixture. FYI..

Mine clunks into reverse all the time. Not sure if it is normal, but mine for sure doesn't die.

 

Thanks okdiscoguy...I'll check the vacuum lines. In reply to your questions, it does not smoke unless under hard accelleration - I am told that this indicates that too much fuel is being burnt. No lights are on...

Well, maybe the clunking is an (oldish)land rover thing and it doesn't sound too nice however it wouldn't bother me to much if the engine didn't stall all the time.

Any more hints, would like to hear from you...

 

Sounds like it is time to clean the idle control and the throttle body, both will cause what you are describing.
Mike

 

Thanks...idle control has been changed by my mechanicas the old one was in a sad state but no difference...will see about cleaning the throttle body.

 

If you don't find the problem, send me your tele number and I'll call you.
Mike
mikeljacobs@comcast.net

 

Thanks. Throttle body has been cleaned but still same problem. I took it down to the mechanic this morningand he is trying to find out what is wrong but if you have any more ideas, I can check them out with him (saves me time and money!).

Mike, I sent you a PM...thanks.

 

If there are no vaccum leaks, the t/body is clean and the idle control unit has been replaced I think you may want to have the mechanic look at setting the base idle. Ask him if he knows how and see what happens.
Mike

 

We alreadyset the base idle but still no go. Vacuum tests have also been done and everything checks out. It could possibly have something to do with the air mass sensor so moving onto that next...

 

Hi again. Just to sum up what happened so far...

1) changed idle stepper motor; and
2) cleaned throttle body
3) reset base idle

The car is running better now however not as well as I would have hoped for as when I put it in reverse it still looses revs (goes down to roughly400 to 500)and then goes back to around 800 or soalthough now at least the engine is not going off. Is it normal to loose revs when putting in reverse or should it remain more or less stable? If not, any more ideas on settling the problem as I am out of them? Thanks.