Windstar Idles high

[mike145]

High idle problem. I had it scanned at a friends shop, and he said the iac was bad and needed replaced. I did so, and the problem still persists. We checked for vacuum leaks and all are good. Even tried changing maf, egr, pcv and tps and cleaned the throttle body. Now I have no codes, but it still idles high when i start it for about 10-20 seconds, and also when driving when you take your foot off the gas it seems to continue to go for a few seconds. Also if I unplug the IAC it runs and drives great, doesn't stall. I did notice that the new iac has a spring and brass rod in it as the original did not is it possible that I need to get one from the dealer? I thought possibly the replacement iac was defective so I took it back and exchanged it for another new one. Any help would be great.

[olopezm]

Hi Mike,

Welcome to the forum!

Did you try resetting the PCM after all those items were replaced? Disconnect the battery for 30 minutes, reconnect and test drive; the first miles might be a little rough as the computer learns optimal values.

Unplugging the IAC should cause the engine to stall when cold but not when hot, in that case RPM's should drop to around 500. If either case makes no change or stalling then a vacuum leak would be the primary suspect, make sure the lines behind the plenum are properly seated and in good condition.

Oscar.

[wiswind]

A couple things come to mind.

Vacuum leak.... Check the line from the top of the intake to the PCV valve.
On 1995 through 1998, the PCV valve is in the rear valve cover....driver's side
On 1999 and newer, the PCV valve is in the front valve cover.....driver's side.
A common place for it to fail is the elbow on the top of the intake.

Another thing that is possible is the throttle position sensor.
If the resistance value is within the normal range, you will not get a fault code.
It could be "stuck" at a value......making the computer think you are pressing the accelerator when you are not.
When I forgot to plug mine in on my '96, I got a code, but the only other thing that I noticed is that it would not downshift when I pressed the accelerator down suddenly (like when you want to pass someone on a 2 lane highway).

A dirty MAF (Mass Air Flow sensor) is also a possibility.