Thread: Over reving, high idle but why?

Knowing what year model Disco might make diagnosis easier, Regards Frank.

The most obvious to me is an air leak into the inlet manifold, you need to check all the pipes and fittings.

Why can't I list my vehicle,the forum does not give me the option.

I'll assume a V8. Search for threads on stepper motor cleaning and repair, and check all the vacuum line attachments to the inlet manifold/plenum. SOunds like either the stepper motor is sticking and there's a vac leak.

hth

Pete

3.5 litre, 1992 model.
Will check over the engine's inlet system and vacum lines this weekend.

Maybe the Base Idle setting has been tampered with?

Certainly sounds like its sucking air to me

Another quick test/check is to reset the injection system by pulling the main EFi fuse for ten seconds.
Look under the cover of the engine bay fuse box to determine the correct fuse.

Had some work done on the old (was trusty) disco a while ago but just not the same now.

Take it back to who did the work and tell them to fix it.

It is impossible for us to advise as we do not know what they did.
There are a couple of candidates that are quite common.

Did they break the T piece in the vapour line to the throttle body and replace it with a normal T piece? The plastic original one has a restrictor to the plenum and MUST be replaced with one with a restrictor.

The vacuum hose to the brake booster can split where it joins the manifold as it goes hard there from the heat.

The ECU will always try for an idle of 650-700 RPM if everything is airtight but any vacuum leaks will stop/slow this down.

This is no different to any car fitted with Bosch LE jetronic so do not accept that it is a"Land rover thing" because it is BS. Tell them if they cannot fix it, they should pay for an injection specialist to fix it.
Regards Philip A