Hey guys-
i have a 2004 explorer XLT 86K on the odometer.
recently noticed that when i have the AC on, the idle surges than drops, then surges again, etc. With the AC off, the idle is smooth.
Check engine light came on with a code P0506, idle out of range.
among the possibilites are dirty throttle body, vacuum leak, etc.
Throttle body was replaced by Ford last January. i plan on cleaning the throttle body and looking for vac. leak.
Any real world suggestions? what should the vacuum be on this engine?
Also when i drive the truck, the fan makes a steadily increasing noise (whoosh?) that i thought would go away when it was warmed up. it almost sounds like the clutch is not working properly.

Before i spend money i dont have replacing parts that dont need to be replaced, has anyone experienced similar issues? what was the result?

 

The Idle Air Control (IAC) should speed allow more air to bypass the throttle plate when the A/C is on to account for the increased load on the engine. You may have an IAC problem. The IAC should function in a similar fashion when the power steering is at lock. You might try turning the A/C off, then turn the steering all the way to one lock and hold it there for just a few seconds. If the idle speed drops with the steering held at lock, that would suggest an IAC issue. You could also try unplugging the IAC at the throttle body and see if the engine stalls. If the engine does not stall and the power steering at lock causes a drop in engine speed, that's a pretty good clue the IAC is not functioning properly.

Certainly check for vacuum leaks though and repair any you find before going the route of the IAC. Vacuum should be around 19 psi at idle and steady if I recall correctly.

-Rod

 

Vacuum 19-21 " Reading your vacuum gauge
If you had a Vacuum leak the idle would rise...

I concur probably bad/dirty AIC, remove and clean...... Philip

 

Just an observation-
While at idle, say waiting for a light, the truck idle s between 600 and 800 rPM as per gauge. If I turn thje steering to a stop, the idle smooths out.

 

Disregard last post- holding steering against stop still have idle issue

 

I would first try to clean the throttle body. Use a cleaner made for that purpose. Google for lots of info on how to do this job including utube vids. Please post back afterwards and let us know if that fixes the issue for you.

ps: I don't think the 2004s still use an IAC for idle control. I believe it's all electronic beginning in 2004 (drive-by-wire) so could be throttle position sensor. But clean TB first.

Good luck.

 

As Aquanaut mentioned, you might try cleaning the IAC to see if that has any impact. While you have the IAC off to clean it, clean the IAC passages at the throttle body as well.

-Rod

 

This is a fly by wire system..
I looked at the throttle body- there are two electrical connections looking from pass side of truck- right side is TPS? Left side IAC?
Didn't find any sign of vac leak

 

If it's throttle by wire it will not have an IAC. The connector on the other side is probably the connector for the throttle stepper motor.

From the Factory Service Manual, the suggested possible causes for a p0506 are as follows:

• Air intake restriction
• Exhaust restriction
• Engine mechanical fault
• Sludged throttle body
• Damaged Electronic Throttle Body (ETB)
• Damaged PCM

That doesn't seem like a whole lot of help, sorry. I'd start with the easy ones, like inspecting the throttle body. A vacuum gauge should help you identify if there is a vacuum leak or exhaust restriction.

-Rod

 

Thenks all.
I wil clean the TB and post back

 

Thank you to all who responded.
I throughly cleaned the throttle body with TB cleaner and there was a fair amount of stuff in there. In fact I placed shop rags in there as I sprayed and they came out brown, literally the entire towel was coated and there were about 7-8 towels that were saturated.
Anywho the truck is running steady idle at least in the driveway and in rev and drive. I will take it out and see how it runs and post back. BTW the vacuun taken behind the TB is 19-21".
Thank you all again

 

another update- the truck runs nice and smooth- no idle issues.
the TB cleaning was all that was needed.

now onto the fan clutch.........