My 2002 Taurus 24V Duratec DOHC developed a low idle about 6 months ago (200,000 km). It would go down to about 500 RPM(park or drive) at a stop and this would cause the oil pressure light to flicker. The car , when cold will idle at 1100 RPM until I take off, then as the engine warms up the idle drops to 500. When the engine is finally up to full operating temperatures after 10-15 minutes the oil light will finally start to flicker. The dealer tells me it should idle at around 650-725 RPM. Through online research I read about low idle so replaced the following without any luck: Idle Air Control valve, Mass Airflow sensor, EGR valve, Throttle Position sensor, oil pressure sensor, and PVC valve with its hose to the throttle body. One Ford dealer after replacing the oil pressure sensor said that I just had a high mileage older car and just live with it. A second dealer did an oil pressure test and said that the pressure was within specs at 700 and 1500 RPM. They also said there was no obvious vacuum leaks. I have had the throttle body cleaned as well and the fuel filter replaced. The oil is changed regularly and the plugs and wires were changed up a couple of years ago. I occasionally run a tank of premium gas and put a bottle of injector cleaner in the tank? Any suggestions what I could check next????

 

Something you might try.
Remove the negative battery cable from the negative post of the battery and let that negative terminal touch the positive cable end for 5-10 minutes to allow the keep alive memory to get erased , then reconnect the cable back on to the negative post. Start the engine and don't touch the throttle pedal thereby allowing the idle system to reset itself.
Let us know if that solves the problem.

 

I am now suspicious that the new IAC valve that I bought last fall was faulty right out of the box. I just read on line of two tests. 1)- with the engine running disconnect the electrical plug from the IAC valve. The idle should immediately drop. Mine did not change at all!! 2) Remove the IAC valve and with the ignition key turned to Accessories only disconnect the plug to the IAC valve. You should see the plunger inside the valve move. Mine did not move even after disconnecting and connecting several times. Did I do these tests correctly? If not how should I do them. I I did do them correctly do the results suggest that my IAC valve is a dud?

 

I replaced mine because of a P1506 code to find out the one I purchased new made the idle go higher . I know what your going threw.

 

Picked up the new IAC valve today that I ordered in, only to find out it is the same brand as the one I replaced last summer(BWD). I think that one was faulty right out of the box but will test the new one tomorrow. I see that it has a spring on the end of the plunger. I saw a message on another forum to NOT buy an IAC valve with this spring as these models have been problematic. But, if my bench tests show that it works I intend to try it out to see if it solves my low idle issue. The one test that I have not done on the IAC currently on my car is to test for the viability of the ground wire on the connector to the IAC. I read that a poor ground wire through the harness can affect the pulse modulation by increasing/decreasing voltage sent to the IAC therefore opening and closing the plunger. Does this sound correct?

 

Not sure about an increase ,but a decrease of voltage sure .

 

Without bolting on the new IAC valve I unplugged the old IAC valve and plugged in the new IAC valve and with KOEO the plunger did not move in the new valve. I did test the connector again and got over 11 volts across the 2 female plug points. Does this sound like another faulty IAC(right out of the box)?

 

We all try to get the best price for what we buy, but with auto parts especially for Ford vehicles best to get the right ones and better quality from Ford. I have many scars from purchasing aftermarket junk, and that's just what it is. Save yourself a lot of trouble and use genuine Ford stuff whenever you can. Not all aftermarket stuff is questionable, but remember, "You get what you pay for ". AND new many times means "Never Ever Worked"

 

hanky, do you have an online source for genuine Ford parts that is more affordable than local dealers?

 

Hanky, I have to tell you . The one that I purchased from autozone reeved the engine higher then my original . I put the factory one back on an let it go .