I have an unusual (I think) issue. My manual transmission 1997 Jeep TJ 4-banger over revs (around 2,000 rpm), but ONLY while the car is moving. Once the wheels stop (or speed drops below 5 mph), the revs drop to the correct ~850 rpm. As long as the car is in motion, the engine stays at 2,000 rpm. So coasting with the clutch in results in 2,000 rpm. Shifting down through the gears is nigh-on impossible, as the rpm stays so high that the car doesn't slow down. I have cleaned the throttle body, replaced the TPS, the IAC, and the MAP. I have used the throttle body cleaning spray to look for vacuum leaks (couldn't detect any). Replaced the PCM. Any other ideas?
They just told on mine to change the clock spring it's behind the steering wheel it throws some type of signal that may throw off your tps. I looked it up and it sounds legit just sucks that it's another 100 part to throw at it going to try it soon good luck
Normal--though 2k sounds a bit high. You may have a small vacuum leak.
However, when your throttle is closed and you are moving at speed (lifting your foot off the gas when the jeep is moving), the PCM begins to use the idle air control to maintain a specific MAP (manifold absolute pressure). Once you come to a complete stop, the PCM enters idle mode where it uses the IAC to maintain the regular 750-850 rpm at idle.
However, when your throttle is closed and you are moving at speed (lifting your foot off the gas when the jeep is moving), the PCM begins to use the idle air control to maintain a specific MAP (manifold absolute pressure). Once you come to a complete stop, the PCM enters idle mode where it uses the IAC to maintain the regular 750-850 rpm at idle.
I don't think it is normal. As you down-shift, the higher revs tries to increase the speed, so it is somewhat unsafe. I replaced the clockspring, and no real difference. I checked for vacuum leaks (I am not expert) and couldn't find anything. I am thinking I might need to take it to a dealer.... unless someone has other ideas?