'99 Sport - High rev problem

[ericnord]

Hey everyone,
I was driving my wife's '99 Explorer Sport the other day and noticed that it was not coming down from the rpms when I would break. So it would be at 2k rpms when I was trying to stop. Then when I left off the break it would accelerate quicker than normal because the rpms were high.

It also did a rough shift that day were we both felt the car jerk. When we got home I put the car in park and gave it some gas up to about 4k rpms and it dropped down to 2krpms, but then got stuck there for about three seconds before dropping down to the normal idle of 1.2krpms.

We also heard the AC start cycling on and off more frequently then normal, and I was wondering if that was related to the idle. She mentioned that the AC hasn't been getting as got lately.

Edit: Took it out again tonight and it is over heating. I had to drive w/ the heat on full blast in order to keep it out of the red.

Any ideas?

Thanks,
-Eric

 

[LiQuiD7EpHeN]

I woulnt worry about the a/c right now. When the a/c system pressure gets low enough it will trip a sensor to disengage the compressor clutch. It sounds like its
short cycling due to low pressure.
The idle I'm not really sure about. have you ever cleaned the intake? the egr valve might be gunked up. Take off the intake tube and buy some throttle body cleaner and shoot it up but dont start it for a while.
The cooling problem could be a couple of things, I'd check for leaks first then if you dont find anything i'd check the serpentine belt for exsessive play if thats not it id change the thermostat if that doesnt work i'd have to say the water pump is shot. I hope this helps you in the right direction. Again im not really sure about the idol problem but i'd clean the intake anyway it gets nasty in there just open the butterfly and shoot away with t/b cleaner.

 

[TPLYNCH]

The engine will automatically run at higher RPM's if it senses an overheat situation. That is why the revs stayed high at idle and it will rev higher before shifting. Your thermostat may be stuck closed. Other possible probs are bad water pump or just a bad temp sender unit.