Return to idle

I suspect there should be a spring to return the throttle lever to the idle position. Without the spring, the throttle plate will stay open and allow the engine to run at high rpm.

if it is a carby engine then check the settings of the automatcic choke and the throttle cam screw settings
it works in a manner so that when you press on the accelerator the automatic choke flips a cam around and the idle speed screw rests on that cam giving a high idle speed until the engine is hot enough not to need a choke at which point the cam is held clear of the idle screw
if efi engine run the fault codes to check for problem accelerator position sensor or throttle position sensor.

No,only on carburated engines it,idles down to the set point,on yours,it's fuel injected,pushing gas pedal won't kick idle down,should go down after a certain amount of time,does it automatically,If you start and drive a 5 mile ride and stop at a stop sign,it should idle at it's set point if there's no engine problems,which may be.5 to .7 on your tac.When you normally first start,it will idle between 1000 to 1200 rpm's,don't push on gas,let idle say 15 seconds,put in drive and go.

I'd hazard a guess that the torque converter disengages from "lock up" when you lift your foot. This would let the engine instantly idle down, and would produce no braking effect from a closed throttle.

Try driving it (at a lower speed) in direct, rather than overdrive, and see if the same thing occurs, or if you get the expected braking effect when you lift your foot off the throttle.

You are hitting the rev limiter top range, which cuts off your ignition.

I have a 2001 Grand Cherokee and the problem drives me crazy, but it is the way the car is designed- as soon as you hit the rev limit, it shuts down ignition and your jeep will "buck" - a real pain when you are trying to accelerate into traffic!

You have the 4.0L straight six engine, yes?

If so, please take my advice and learn to live with the minor annoyance of the rev limiter- that engine is IMHO the best Chrysler ever made (nearly "bulletproof"!) and it was so reliable you cannot even get it in a jeep now! For decades, that engine was used in welders, tractors, generators...and yes, jeeps... and it is a favorite among mechanics for its durability!

throttle sensor fault. might be cleanable if removed. also could be a damaged idle valve, might be staying open this cal also give high revs. and tap and it will go down as its sticking. acceleration is the throttle sensor i may have blank spots. removing it and spraying in the switch breather hole and shake the cleaner around and turning it at the same time should clean the sensor. then shake and leave to drain out the cleaner. idle valve you will need to remove it and clean ti with some carb cleaner and a brush like toothbrush, clean it thorley out push the pin in and out to make sure its not sticking at same time spray it. then when clean leave to dry. then refit them. hope this helps

the gearbox is a "fuzzy logic"system.gearchange depends on accelerator pedal position/revs/load.if you drive without depressing the gas peddle more than a third down you should find all gearchanges much smoother.(if you drive with gas peddle almost hard down all the time yhe car will hold gears longer...poss 4500 revs or more......

chances are this vehicle is what they call "drive by wire". it incorporates 2 position sensors, one on the accelerator pedal and one on the throttle body. if one is not working it will not accelerate. have it towed to your dealer to be corrected.

check operation the throttle control motor or cable if used ( broken /missing return spring

umh dealers !!!!!!!!!! if you know somebody with an oscilloscope get them to check it out for you,did they reset throttle body basic settings ? if you live near canterbuty in kent i would be able too help,e mail me for further help [email protected]