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[/ATTACH]I have just gotten a 94 F150 XL with the 4.9. It has got a high idle on it and looking under the hood on the dirver's side I saw a wire with a gray plug dangling down near the oil filter. I never could see anything to plug it into. I did notice something like a rail that had two sensors or some kind of boxes attached to it and there was a place that looked like a third item could be attached. It was on the end near the firewall. I don't know if this, whatever it is, would have anything to do with the idle, but curious to what it is!

 

Not sure, but it looks like the test lead thing (not to sound too technical) that you use in junction with the EEC plug to read codes. I think it's some sort of jumper.
I could very well be wrong, but I set out on the same search and that was my end result.
Lastly, is there a plug hooked into the base of your coil? Looks similar to that plug as well (SPOUT I think?) Either way, there should be an electrical plug in the base of your coil as well while checking around under the hood

 

That is not the EEC test plug. Maybe you can make the pictures smaller? It's not challenging enough.

 

Here is a bigger pic of the area that I was wondering if something was missing that the plug might go to. There are notches in that metal piece that are just like the ones to the left that have things plugged into them. It just seems like whatever was there was taken off. I'll look at the coil tomorrow. I just want to get that idle down because it's too fast to put in gear!

 

man that blurry.....I cant even make it out

 

Now that's challenging.

 

I think it's either the EGR solenoid, or one of the 2 smog pump solenoid wiring plugs. The rail he's referring to holds those 3 solenoids.

Is your EGR system hooked up? If not, it's the egr solenoid plug, but if it's already disconnected and blocked off, it could be for good reason. It can get expensive trying to get an egr system back up and functioning.

If it's the smog pump wiring, and the smog pump is already disconnected from the exhaust and intake, I wouldn't worry about it. It's honestly pretty useless unless you have emissions testing.

But you really need some bigger pictures.

 

Would either of these (EGR or smog punp) have any affect on the idle?

 

Not if they're blocked off. My egr is blocked off and the smog pump has been disconnected and my idle is fine. If you have an egr and smog pump that is only half functioning and has a vacuum leak then it would definitely effect your idle.