Disco I 1997 158K
I did my homework and searched previous posts on the issue, but no help.
My idle was fine but I started having problems to start the car when hot.
I traced the problem to the fuel pump. The fuel pressure was very low.
I replaced the fuel pump and the crank sensor. Again, my problem was NOT the idle. When I reached the crank sensor to remove it, it was very loose, I would say about to fall off, but my car run just fine (other than the starting problem). Ok, new fuel pump, new crank sensor, fire up right on. Run fine for one day. Next day I start the car and the idle is 2000 RPM. What happened? After that I checked for vacuum leaks, cleaned the stepper motor, but the high idle remains. I am strong believer in cause ad effect. It is hard for me to think that the parts I replaced had nothing to do with it, and that the steeper motor went bad overnight, right after replacing the fuel pump and the crank sensor.

 

Don't mean to sound like an ***, but did you put the right fuel pump part number in?

 

Well, I think so, that is what British Atlantic sold for my car model. But I don't see what that could have to with it. The fuel pressure is right were is supposed to be.

 

My stepper motor did the same thing right after I replaced a clogged fuel filter. It seems to be the main thing that controlls the idle mechanically. I also found out that (in my case) third party stepper motors can not be initialized. So be careful about third party motors.

 

When did you last clean your t/body and the IAC for carbon?

 

That was the first thing I did after searching here in the forum. Seafom and pulled out the steeper motor and cleaned it. I've noticed that it has come down now to about 1300 from the 2000 RPM the first week. It is not my daily driver, maybe I need to drive it more. We'll see.

 

check clearing the codes and resetting adaptions. That gets it down unless you have a massive leak say from a bad pcv hose.

 

Thanks Rovin. I don't have any codes, at least I think so because my CEL is not on. Last codes I had was before replacing the fuel pump and they were about O2 sensors. Got those replaced and no CEL on since then. I will check again for leaks. Thanks

 

When I put a new fuel pump in my 97 I had the same problem, idle around 2000, the only thing that was able to bring back to normal was to have the dealer reset the adaptive values on the ecu. I guess the ecu is used to dealing with a pump that isn't working to it's full capabilities so when the new pump is pumping more fuel/higher pressure it doesn't know what to do or takes a good long time to adapt t it. After the dealer reset the values, the idle was normal.