I purchased a 2001 Windstar from my daughter and son-in-law that seems to have always idled fast. When the engine is first started cold, it idles at 1500 rpm until it starts to warm up. Even after it is warm, it idles at about 1000 rpm in neutral. I had a Chev Venture that idled at about 800 rpm when first started.
There are no vacuum leaks that I can find. Vacuum is a strong 20 inches at idle. The vehicle has had the P0171 & P0172 codes for the last 3 years but has not affected engine performance. It high idle speed common on this engine?

Thanks in advance.

On my 2000 3.8L, I had the same high idle speed a couple years ago. Would never drop below 1000 rpm even when fully hot. This made the car always run fast on level or downhill and think it contributed to needing new front discs at only 35k miles.

I removed the IAC (idle air controller) and sprayed it out good with cleaner and allowed to fully dry. After putting it back in, the idle dropped to ~800 rpm when warming up and about 650 rpm in neutral when fully hot. Now I don't have to brake as often on downgrades.

Do a forum search on IAC and cleaning for extra tips....

Just by chance, I was watching our van's idle speed this afternoon. Our 2000 w/ 110k km was idling at around 750 rpm with the engine at normal running temp. No lights on. AC is off. Tranny is in park.

Thanks for the tip on cleaning the IAC. I will try it and post the results.

I cleaned the IAC with electronics cleaner, but the engine still idles fast. The IAC valve was clean when I took it off and the electrical tests indicate it is ok.
Is the valve normally open. Mine was. Any other suggestions?

I cleaned the IAC with electronics cleaner, but the engine still idles fast. The IAC valve was clean when I took it off and the electrical tests indicate it is ok.
Is the valve normally open. Mine was. Any other suggestions?

Which valve are you referring too? The throttle valve should be fully closed when you aren't pushing down on the accelerator pedal. Could the cable linkage from the pedal or cruise control be binding up and not allowing the throttle to fully close? The IAC allows a little air around the closed throttle valve as needed for the proper idle speed.

There is no "idle adjusting screw" on modern cars like the old days with carburetors. If the idle is too fast, then somehow extra air is entering the intake and the PCM is giving the injectors a signal to add some fuel to avoid a lean condition. This causes a faster than normal idle.

At least that's how I think this works - :confused:

It can be many things.
1) It can be the accelerator linkage that is sticky. Check the cable.
2) It can be the fuel injection system. Such the fuel filter, feul pressure, injectors...
3) Any of the engine control system: TPS, MAF, IAT, O2 sensor, EGR,...

It's not necessary easy to diagnose this problem, even if it's sound simple.

No. - to the initial post title question.

I would focus on clearing the codes.

Was there any recent work done to it? If so, what was done?

I would leave a vac leak as a possibility until the codes are gone.

Check what previous poster says.

It could also be the PCM or ICM (inside the PCM in your year).

Just cause the IAC is clean doesn't mean its good. In fact if you have high miles, it being clean could be an indicator that its not functioning. It should've been fairly dirty.

Clearing codes is not a good idea, the OBD will freeze, and he'll not be able to read future code within 2000 miles or more.

I don't think that is a Vacuum leak, cause the pressure is 20 inches Hg. It's very good.

I just remember that a bad or dirt MAF sensor can cause the code P171 & P172.
So check your MAF sensor.

I agree to check also the IAC and PCM.

Thanks for all the response. It was the IAC valve that was open when I removed it. The van has 153K miles on it. I did clear the codes and will be putting on over 3,000 miles in the next 3 weeks. I've put on 580miles since I cleared the codes and the service engine light hasn't come on. It probably hasn't gone through enough start cycles yet.
I do need to clarify that once the engine is up to operating temperature it idles fine. It's only when the engine is cold that it idles fast. The linkages all are working fine.
I will check the maf sensor next.

In a Windstar, it's normal that it idles at 1500rpm when it start at cold. That's the quick warm period. But after 10s or when we put in Drive, it should reduces at 1000rpm, then at 750rpm after 20 more sec.

The opeating temp is at which portion of the temp gauge? A stuck open thermostat can cause this problem. Or an old ECT sensor.