Weird engine reving at stops.

[novabrian]

I have a 2000 Ranger with a 4 cylinder and manual 5 speed.When I got to shift let off the gas and push in the clutch it revs to about 3000 rpm then slowly goes down to idle.It also does this when I come to a stop.I have replaced the IAC valve and still the same problem.What can I do?

 

[BRUTUS_T_HOG]

check for vacuum leaks, do you have a check engine light on yet?

has anybody played with the throttle stop screw?

 

[novabrian]

check for vacuum leaks, do you have a check engine light on yet?

has anybody played with the throttle stop screw?

Throttle stop screw is all the way backed out.I have checked for leaks.The check engine light was on.But way before this problem started.I did however clear the computer and got the check engine light go off.

 

[red85]

Check all those crappy rubber hoses and I'll bet you find a vacuum leak. I have seen the little rubber elbows get dry and cracked and create the same symptoms you're having now.

 

[disciplerocks]

I would say iac or vac leak. Once you find it, clear your ecu and run it for a bit without the ac or defrost on so it can learn new fuel trims.

 

[Fanucman]

I have a 2000 Ranger with a 4 cylinder and manual 5 speed.When I got to shift let off the gas and push in the clutch it revs to about 3000 rpm then slowly goes down to idle.It also does this when I come to a stop.I have replaced the IAC valve and still the same problem.What can I do?

This is going to sound stupid, but have you checked fuel pressure above idle? Mine does the same thing and I just figured out today that my fuel pressure falls off at high RPM. It really seems to screw with the computer. I may be way off but it might be worth checking out.

 

[novabrian]

This is going to sound stupid, but have you checked fuel pressure above idle? Mine does the same thing and I just figured out today that my fuel pressure falls off at high RPM. It really seems to screw with the computer. I may be way off but it might be worth checking out.

Nope haven't done this.I have no way of checking the pressure.

 

[Fanucman]

Nope haven't done this.I have no way of checking the pressure.

If you have an Auto Zone nearby they have a loan-a-tool program where you can just borrow one. You pay for it but get a full refund when you return it.

 

[novabrian]

If you have an Auto Zone nearby they have a loan-a-tool program where you can just borrow one. You pay for it but get a full refund when you return it.

Yes I always forget they loan tools.

 

[suprapsu]

Get carb cleaner and clean out the throttle body. It may be because the throttle body is sticking.

 

[Duane867]

Sounds like a vacuum leak to me or a dirty IAC.... spray some either ( after its idled down to begin with ) around the lines and the intake manifold. Could be a sticky butterfly in the throttle body as well, or a sticky accelerator cable. Some times they rust on one end and get moisture in the cable its self and rust up inside the cable causing it to stick and slowly return to idle. That's not all that common though. remove your IAC and clean it as well.
Checking for leaks with either, cleaning the IAC, lubing up the linkage, and checking your accelerator cable would be the easiest, most common problems, and cheapest to do 1st.