ATT Ford guys!

[demarpaint]

I've been working on old faithful a little (88 E-150 4.9L 5 speed stick), when the rain stops. I had a problem with the engine bogging down and will be doing a complete tune up very soon.

I have all kinds of parts for this van. I found a part I had never installed, it is called a Idle Air Adjust Spacer. It is a metal plate that sits under the IAC. Set up is pretty simple, and initial adjustment is fairly easy as well. Once installed there are 2 allen screws that take over curb idle adjustment instead of using the throttle plate stop screw.

My question is this: Once installed if the curb idle is a little high, do I have to disconnect the battery each time I make an adjustment to tweak the idle so the computer can re-learn. Or do I just make the adjustment. I have a slight issue with engine surge when I turn on the defroster and think this plate might be the ticket. No codes everything is up to spec, I'm just toying around with tossing in this spacer plate.

TIA,
Frank D

 

[punisher]

Those are absolutely worthless. We were issued those as part of a TSB fix for idle concerns/rough idle etc. Many came back for idle concerns after they were installed per directions and were removed (I have a few in my tool box I think). Ford had some problem with us techs desludging throttle bodies and cleaning IACs so they issued this kit to let in more air at idle. Not one of Ford's better ideas.

If you are intent on installing it, Warn up engine, disconnect IAC connector (sometimes you might have to disconnect the SPOUT connector as well), connect tachometer, set idle to spec directions are on the underhood sticker). Hook up IAC and SPOUT. Disconnect battery for awhile, reconnect and set idle strategy. The initial opening on the allen screws depends on engine. Start off with about 1.5 turns and go from there.

..............or do a proper desludge of the throttle body, separate and clean the IAC, reset idle strategy and see how that works.

 

[demarpaint]

Thanks Punisher!

Wish I would have read this sooner. I put the part on and followed the directions, the curb idle seems a little higher than I want. Can that now be lowered via the allen screws? It said turn clockwise to lower the idle. If I do this do I have to reset the strategy each time it is tweaked?

Something that always annoyed me with this engine and the standard transmission was the idle takes a few seconds to settle back down to normal idle speed when you come to a complete stop and push the clutch in. It will hang at 1000 rpms and then settle down, turning on the A/C it will surge. I've dealt with that for a long time now, thought that part might help.

Can I leave it on? The TB etc are spotless, I cleaned them in prep for a major tune up.

Thanks again!

 

[punisher]

You can leave it on. Unplug the IAC, set base idle according to your sticker directions. Just crank the screws in to cut down the air flow.

I think, and I could be wrong, but the I6 was such a dirty engine (from a HC point of view) that the PCM is keeping the IAC open longer (like a dashpot) to reduce emissions when it goes to idle. To be fair I didn't work on a lot of 300s. Most problems on those were injector or air temp sensor related.

 

[The_Jeff]

To see what effect the IAC has just idle the motor and cover its intake hole with your finger. If you really want to "tease" the motor release your finger and see if, since it opened the passageway, it overshoots and then corrects.

 

[demarpaint]

Originally Posted By: punisher
You can leave it on. Unplug the IAC, set base idle according to your sticker directions. Just crank the screws in to cut down the air flow.

I think, and I could be wrong, but the I6 was such a dirty engine (from a HC point of view) that the PCM is keeping the IAC open longer (like a dashpot) to reduce emissions when it goes to idle. To be fair I didn't work on a lot of 300s. Most problems on those were injector or air temp sensor related.


It seems to be idling better, I set the curb idle according to directions I had printed. Never thought to check the under hood sticker, IIRC it says to check the emissions manual.

When I set the curb idle I disconnected the IAC, but not the spout connector, then disconnected the battery for it to learn the idle strategy.

Should I do this over again disconnecting the spout connector as well as the IAC, or leave well enough alone, and tweak with the allen screws? Then let it re-learn the idle strategy?

Thanks again!
Frank D

 

[demarpaint]

Well my OCD is going to get the best of me, and I am going to try to set base idle with the IAC and Spout connector disconnected. I set it with the IAC disconnected only, it seems OK I guess I'm looking for perfect. I have the day off a some good weather, it is best I strike while the iron is hot.

As it turns out I had the truck in for inspection and I come to find the mechanic "tweaked" the idle, and that is why I am going through this process.

In defense of him I needed a tune up, and I complained of a rough idle but I'm not happy with the tweaked idle. I plan on changing out the plugs as well, and am waiting on a copper cap and rotor I had to special order. Seems all the cap terminals are aluminum and they suck!

 

[The_Jeff]

Sounds like a "wells" dizzy cap. Junk! Hope you got a nice one coming.

 

[demarpaint]

I went with an Accel cap, they couldn't get me the Standard copper cap. Wells is garbage for sure.

Still wondering if I tweak the curb idle with the adjustment screws on the plate if I should disconnect that battery and let it learn the idle strategy again. Jury is still out on that!

 

[punisher]

Tweek the idle with the engine warm, IAC plug disconnected. Play with the allen screws untill you get the idle to spec RPMwise. Disconnect battery for awhile, reconnect and reset idle strategy.

Hate to admit it (cause I was an evil dealership tech) but SOP on the TSB after awhile was to install the plate with the screws cranked all the way in, and clean the IAC and throttle body out properly. Leave the spout connector in.

 

[OVERKILL]

The idle reset procedure can be just as easily done with the throttle stop screw, and nicely omits the mickey-mouse plate.

 

[demarpaint]

Originally Posted By: punisher
Tweek the idle with the engine warm, IAC plug disconnected. Play with the allen screws untill you get the idle to spec RPMwise. Disconnect battery for awhile, reconnect and reset idle strategy.

Hate to admit it (cause I was an evil dealership tech) but SOP on the TSB after awhile was to install the plate with the screws cranked all the way in, and clean the IAC and throttle body out properly. Leave the spout connector in.


I did it, with the spout connector and IAC disconnected earlier today. I had the weather and time on my side, wish I would have seen this earlier. Idle when things were reconnected was a little too high, that was after I reconnected the battery let it run about 3 minutes then turned on AC and took a 20 minute drive.

When I got back the engine was good a hot I tweaked it with the allen screws, but I had the IAC connected. I noticed the idle drop, I shut it off then disconnected the battery and repeated the above procedure. It idles fine now.

Hope disconnecting the spout connector didn't matter, I don't want to do this again.

Will my seat of the pants job work? There is no adjustment on the TPS.

THANKS FOR ALL THE REPLIES!!!!!!!!!!!

Frank D

 

[punisher]

Originally Posted By: OVERK1LL
The idle reset procedure can be just as easily done with the throttle stop screw, and nicely omits the mickey-mouse plate.


Not wise. I can honestly say I have never had to adjust the throttle body on any Ford with an IAC. The one I did adjust, early early in my shop days, came back and bit me in the [censored]. Idle problems (On Fords) are due to vac leaks, sludged intake parts, incorrect timing (cam and ignition), goofy EGR etc, or just about anything but the hard idle stop. Just a golden rule I learned early on.

 

[OVERKILL]

Originally Posted By: punisher
Originally Posted By: OVERK1LL
The idle reset procedure can be just as easily done with the throttle stop screw, and nicely omits the mickey-mouse plate.


Not wise. I can honestly say I have never had to adjust the throttle body on any Ford with an IAC. The one I did adjust, early early in my shop days, came back and bit me in the [censored]. Idle problems (On Fords) are due to vac leaks, sludged intake parts, incorrect timing (cam and ignition), goofy EGR etc, or just about anything but the hard idle stop. Just a golden rule I learned early on.


I've had to do it numerous times. But of course these are on vehicles that are not stock. It is not unwise, provided you know what you are doing and doing it for the reason I just touched on.

If somebody has been playing with the throttle stop screw, there is often a REASON to do it on a stock vehicle

A lot of people think they can just move it like on a carb..... Not realizing that they can easily put the TPS out of range doing so.

 

[demarpaint]

I seem to be idling fine and the annoying surge is gone. The IAC and the hole it sat on were clean.


Anyway since I am idling OK now, and the TPS on this engine has no adjustment should I leave things alone?

Thanks!

 

[OVERKILL]

Yes, leave it alone! LOL!

 

[demarpaint]

Originally Posted By: OVERK1LL
Yes, leave it alone! LOL!


Thanks for keeping my OCD in check!!!!!!!!!!! On occasion I get a little crazy with details. I promise I will leave it alone, and if and only if it needs an adjustment I will disconnect only the IAC and make the adjustment via the allen screws!!!!!!!!!!!!!!!!!! I promise!

Now I have to work through this slight bogging while cruising..............Got to love these 20+ year old treaures.

Thanks for the help guys!

Frank D