high idle at start up

My 97 disco seems to idle really high when i first start it up like close to 2700rpms maybe a lil higher. Once i put it into gear the idle drops right to around 900 rpms and stays there. After i drive around for a bit and put it in park the idle stays right at the 900rpm level. leave it for a couple hours or over night and go to start it and then the idle is right back up to 2500-2800. Any ideas on what this could be? Any help would be much appreciated.

It more than likely the Idle air control valve, remove it then clean the plunger, also clean the area the surface where the plunger makes contact inside the manifold, dont connect the wire hasness, start the Disco, connect the wire harness, then disconnect it for about 5 to 10 seconds, then reconect it. also look for any air leaks around the manifold and the intake tubes, if none of this works, tighten all the lower manifold bolts, they have a tendency to come loose.

GOOD LUCK!!!!!

agree 100% check the ICV first and then for vacuum leaks. FYI Paul Grant is a great resource for used parts in CT he is over near Gaylordsville. his email is paulgrant@mac.com

Thanks guys ill clean up the IACV and give all the vac hoses a good inspection.

Cleaned iacv, port it goes into and throttle body, checked for any vacuum leaks and didn't find any. There was no change to the high idle at cold start up.

There could be a couple of things here.
First off check the idle bypass screw on the plenum its under the aluminum cap
by the throttle plate if the cap is still there. It should be around 3/4 to 11/2 turns from closed
using a 3/16 allen. If you are still having a high idle issue after adjusting it,
you'll need to find someone to reset your closed throttle.
Did you recently replace the battery? What type is it.
If after you reset the closed throttle the idle is ok for a day then it reverts back to a high idle
then I'd recommend you put a new battery, not one of those red tops. just a good old interstate
or die hard then have the closed throttle reset again. I've seen several high idle issues
that have been caused by red tops and off brand batteries.
If you have to go to the dealer or indy shop and they can check the base idle with their diag equipment
have that done also. the 3/4 to 11/2 turn is just a ball park #

Cheers

Mike

I replaced the iacv... And I have replaced the battery when I bought it a few weeks ago with one of those everlast ones from the part store. Could that be the problem?

Sarge103 wrote:

I replaced the iacv... And I have replaced the battery when I bought it a few weeks ago with one of those everlast ones from the part store. Could that be the problem?

Did it start when you replaced the iacv? if yes then you need it reset.

no the high idle was the reason i replaced the IACV the old one was so cruddy i couldnt get a majority of the gunk off when trying to clean it.

Sarge103 wrote:

no the high idle was the reason i replaced the IACV the old one was so cruddy i couldnt get a majority of the gunk off when trying to clean it.

Ok, sounds like you need to get the new IACV reset. Try starting the Disco, then unplug the IACV, wait 15 to 30 sec then plug it back in, This has worked for me in the past, You might need to do this after a drive cycle. Or to make it easy just go to a shop and have it reset.

Did you check the intake bolts, running at idle over 2000 rpm sounds real high even if the iacv is off, sounds like a masive air leak.

Vader wrote:

Did you check the intake bolts, running at idle over 2000 rpm sounds real high even if the iacv is off, sounds like a masive air leak.

Ill check the intake bolts for proper torque just to make sure. I already tried the un plug power on/off reset, and i talked to my local LR shop and he said 70 bucks to reset parameters if need be.

did you figure it out I have the same problem