Apparently, the idle speed is totally controlled by the computer? I have checked for error codes, and there are none. Replaced the Throttle Position Switch.

I would guess that its 200 rpm too high, and I really hate fighting it at traffic lights, and in parking lots, and am no fan of the 'clunking' when I put it in gear. I am thinking of pulling the throttle body, but I don't really know why :-) or what I can expect to do once I take it off. Do they "wear out" or can they be cleaned and replaced, or adjusted? Doesn't look too hard to get it off, just not sure if its worth the time and effort, towards getting the idle back down.

Is there somewhere else I ought to be looking?

Much obliged for any suggestions.

John

 

Try unplugging the IAC (Idle Air Control).. If the engine stalls, or RPM drops off close to stall,IAC should be OK..If 'no difference, suspect the IAC stuck/plugged or failed.. Also, check for any unmetered air, vacuum leaks in the system.. Here's a 'typical' IAC for reference..

 

You could have a slight build up causing the throttle plate not to close all the way. Had this problem on my 94 Sable 3.8 caused by PCV valve deposits.

 

Thank you. Can you expand on what this is, and where it is plugged in? I only have an old Haynes manual, and it doesn't seem to be mentioned anywhere I can find. I am not yet very familiar with this engine, so I don't want to screw it up.

Its a 3.0L, 4spd auto, 1993

As an aside, I search for shop manuals, and only seem to find the ones that are on CDs.... Do you have an opinion as to the value of those resources? Can't be any cheaper, but still, I wonder if are they just ripoffs?

Thanks for the assist. I have been knocking down the issues with this car one at a time, and can actually see the light at the end of the tunnel :-)

 

So you replaced the PCV, and did you have to remove and clean the throttle body? Just curious how you managed to solve the problem. I don't want to tear off parts that I am not familiar with :-)

Thank you very much,

John

 

IAC problems 'generally' will cause a lower RPM or stall going into gear if not functioning, but something to function check for idle control.. Just unplug the electrical connector on the end during idle.. RPM should drop if the valve is working.. Sludge build up on the throttle plate and bore is common, and could go either way for a higher that spec idle, or lower if the buildup restricts the intake plate and/or IAC.. Also check to make sure no one has bent/adjusted the throttle stop tang to correct for a sticking throttle plate.. As the throttle shaft/bore wears sometimes the plate will stick when closed and will give a 'snap' feel on a take off.. If the stop is bent it can hang the plate open too far.. You can use throttle body cleaner and a soft brush/rags to remove the sludge and doesn't require the T/body to be removed.. And again, check for any vacuum leaks, PCV/hose condition ect..

Here's the pic.. Don't know why it didn't come through before.. This a typical IAC, may differ from your application

[IMG]local://upfiles/6756/9FAFB87FB58646AE873601210F6C2AF6.gif[/IMG]

 

Like Hayapower said...I just removed the hose from the throttle body, held the throttle plate open and sprayed cleaner in. Brushed the crud away with an old tooth brush. Fired the engine up and ran some more cleaner thru the throttle body.

 

Wow! I really appreciate all the pointers. I have some work to do this weekend, and with a little luck, I have enough to go on, that I should be able to take care of it. Already learned more here, than the repair manual could offer up :-)

I'll be back, hopefully with good news.

Thanks very much to everyone.

John

 

Good luck and have fun...

 

Oh, I have been having fun all right :-) Gonna resurrect this older thread, as I did as was suggested. Unplugging the IAC kills the motor instantly, which I guess is a good sign. The TPS is replaced, as is the PCV.

What happened is, I tried all the suggestions, and even did a bit of Gumout into the throttle body and scrubbed around the plate with a toothbrush.

Nothing seemed to help, so I figured what the heck, and went to town with the Gumout. There is a sticker on the throttle body that says not to do that :-) but I did it anyway. In addition, the Ford Shop manual I bought, says not to use carb cleaner as there is an o-ring that can be affected. They say to use some ford cleaner, a part number I don't have right in front of me.

Spraying, racking the throttle back and forth, probably a quarter of a can of gumout. Let it sit, moved the throttle around some more, and wiped out what was accessible. Started it up, after a ton of cranking :-) and lo and behold, its back to idling pretty decent.

That was a month ago. I don't drive it much, but saturday, I took a long drive in the blazing heat, and when I neared home, the idle started going up a bit more at each traffic light. By the time I got it home, I was going 25mph without touching the pedal....damn.

I rattled the throttle by hand, at the throttle body, and it came back down to normal, so something is obviously hanging it open.

Should I just take out the IAC, and spray the inputs again, even more? I am concerned about the Ford comment not to use such a method, so I figure to ask the people who have actually worked on these things, and used such methods.

I know, its long winded, but I just want to get the facts out there, in case it rings a bell for anyone...Its so dang hot, I would like to have a good plan, before I even go out there and start taking things apart :-)

Gumout into the throttle body and plate. Good or bad thing to do?

Thanks very much.

John