Hello guys new to site i have a 1998 land rover discovery 1 with a high idle problem. No check engine light i changethe idle control valve but didn't fix. The computer said the truck was doing 56mph sitting still and -40 degrees in florida. So i picked a used computer and it didnt help. So looking for help on that.

The second on is the radio is just reading code and can't get the code to work. Tried few times, left battery off and tried after long time, then left key on for couple hrs and tried still doesn't work. So looking for help on that too.

 

Well i got the radio to take the code number and work. So one down now need to get the idle fixed

 

I had a similar problem. I had to have the ECU reset by the dealership because the voltage to the throttle position sensor was too low.

 

Well still have high idle replaced temp sensors, iac, computer can't find problem! After the rover has warmed up idle is normal so i un plug iac and runs great.

New problem over heat issues now replaced fan clutch was bad, replace thermostat, water pump and chemical flush. The electric fans new last year and working fine. When i run ac it start boiling in seconds after warm. I have to run heater to keep it from boiling over but will still run on high side after about 30-50 miles. I shut off and you can hear the fill bucket boiling. My father can drive 10miles every day and it just get warm. It has 140k miles on it im second owner and never had issues untill couple months ago with high idle. The only thing i have tried was pressure test yet just placed water pump Friday and garage can't figure out the idle issue.

 

Just some ideas for your fast idle, Leaking injectors? computer might be trying to compensate for too much fuel(?) bad o2 sensors(?) or leaking exhaust(?)worn throttle body leaking air (?) vacuum hose damaged or leaking, brake booster leaking, Just some thoughts you may have already checked, but worth mentioning