1999 Range Rover HIGH IDLE

Is there a check engine light on? That's where we need to start. Perhaps it will tell you if the system it LEAN, indicating a vacuum leak. It may not be that simple, though so lets start by checking for diagnostic trouble codes.

Do you have a scan tool or just a code reader? If you have a scan tool, look at the IAC pid. It should read 20-25 steps and the MAF sensor should read approximately 1.4 volts at idle. When the engine temp is cool, it will be in 'open loop' and when it warms up, it will go into 'closed loop' and will start adjusting various things based on sensor inputs. When in open loop, it's running on preset values within the PCM/ECM. This could explain why it idles correctly when cold but the idle raises when it warms up. Something is telling it to idle up. You'll need a scan tool to determine what, though. Start by watching the IAC steps and the MAF voltage. Let me know what those values are and we'll go from there.

You can buy one at 'Oreilly's' or online. They're pretty pricey tho. You will a lot better off to take it to a shop and let them do it. They'll be able to monitor all the inputs from the sensors and determine why the idle goes up when it goes to closed loop. That stuff can get pretty technical. Just check all the basics first. Make sure there are NO vacuum leaks. Do you hear any 'hissing' noises while it's running? I sometimes spray some carb cleaner around and see if the rpm's fluctuate any. If no vacuum leaks are found, take it to a shop and let them take it from there. I'm sorry but that's pretty technical stuff and hard to deal with without the proper tools.

Well, it's hard to say. If you brought it to MY shop, I would ask you a lot of questions about what all you've done and haven't done. So offer that info to whoever you take it to. That may save them some time and you some diagnostics costs. But, even knowing what you've already tried, I would still probably somewhat start from scratch just because I've been doing this for 20 years and I kind of have a routine for diagnosing problems. It would not be because I'm ignoring you, but just to satisfy myself. Good luck and let me know if I can help you in any way.