Hello, I have this problem with my 1990 Bronco that I hope somebody can help me with. It is a fuel injected 5 liter (big one). I am not sure what parameters the idle setting should have. I set it last at 800 RPM while in gear, AC on and pressing on the brake. However, when it is in neutral, AC off it shoots to 1500 RPM and stays there. If I set it lower, it dies when AC on and in gear. The whole idle setting started since I am trying to figure out why: - it does 7 MPG and it should do 10-12 MPG, right ? Used to before they changed the water pump and started having overheating problems. - it STINKS from the exhaust fumes. I have never smelled a regular truck smell so bad. The mechanics changed a bunch of sensors, there are no error codes, checked timing, psark plugs, distributor cap, etc. It runs great, but will bankrupt me. Any ideas ? Thanks, Konrad Szwab, EE Systems Engineer / Network Administrator Alcon Houston, (713) 295 4329

You don't say which sensors were changed but I am assuming they were the normal temp and oxygen sensors. You don't say wether the idle air control valve was checked or not. You also don't say how you are adjusting the idle. If you are using the throttle stop screw you are doing nothing but fooling the computer into thinking you have your foot on the accelerator by slightly changing the position of the throttle position sensor. The computer contols the idle through the various sensors and the idle air control valve. Did the mechanic check the computer itself? That may be the culprit. Here is something you may try, especially if the battery was never disconnected while the sensors were changed. Readjust the idle to 800 RPMs in park with no accesories running. Disconnect the battery for at least 5 minutes. This will clear the computer of any previous settings. Drive the truck for at least 10 miles at a steady speed. This will allow the computer to recompute engine conditions and fuel mixture (again I am assuming the oxygen sensor was changed). If this does not help try changing the Idle air control valve and reset the battery again. If this does not work, find a reputable facility to check the computer.