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zekenator said:
Intake is all stock except for 1/2" spacer under stock intake.
This could be a possible reason for your idle concerns all in itself. The intake's got a spacer which is one more seam to have to seal in the intake tract. As a couple other guys found, if the intake was leaking, or the tb was leaking, then the car wouldn't properly idle down. Look back in the thread to find the posts about how to check for intake leaks.
-Matt
 

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I did try the ten pin connector trick. Didn't help my car. I still have the idle issue when you come to a stop. Nothing else but that. Does have a surge when first started in the morning. Idles about 1200 rpms when you are coming to a stop light until you come to a complete stop, then goes to about 850 or 900. Not sure on what else to do. Thread has alot of great info. Thanks! Although I didn't clean the connector. Should I do it again. What about the IAB? Not sure what that is or where? I'm no mechanic by no means.
 

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Discussion Starter #203
Fiddy211 said:
... I still have the idle issue when you come to a stop. Nothing else but that....

Does have a surge when first started in the morning.

....Idles about 1200 rpms when you are coming to a stop light until you come to a complete stop, then goes to about 850 or 900.

... What about the IAB? Not sure what that is or where? I'm no mechanic by no means.
The car is suppose to idle up to 1200 when you are in motion but not on the throttle. If it drops back down to 850-900RPMs based on the stock tach with in a few seconds of coming to a full stop, then all is good.

I surge at start up is intentional as the EEC is setup to idle up like a choke would on an older carb setup. This gets the sensors/engine up to operating temp and allows the car to pass emmisions testing with less hassle. This time period lasts about 2mins if I recall correctly. I am pretty sure this was disscused in the this thread some where.

Now, if your engine will stick open at say 1800-2000 RPM's after it has started up and has come up to full temp then I would suggest looking at your IAB valve. it's the sliver canister that bolts onto the throtle body and has a black connector on it. Remove the two screws that hold the halfs together and then clean the half that bolts directly to the TB that has the two large holes in it.


Here is a good link on cleaning, it's 94-95 based but it's very similar to the 87-93 design that ford used on the foxes.

http://www.muscularmustangs.com/iac.php
 

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quickbrick said:
Hi Darren. I can adjust the base idle up or down with that set screw, but I'm talking about the delay in rpms dropping back down to idle speed after the throttle is released - the revs stay up for a second or two instead of coming right down as they should.

When the IAB valve is unplugged, the idle drops as it should. Some guys at a local Ford speed shop (Racer Walsh) have the same problem but no answers.[/
this is my problem also
 

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IAB?

Wangstang said:
The EEC is supose to idle the engine up while in motion but at closed throttle, the idea being that you don't stall out as easily if you all of a sudden put it in gear or punch it. That said it usually keeps the idle while in motion around 1200-1400 RPMs from what I recall. SO...

You mentioned that you have an E-cam and that the car was an auto converted to manual.
I just went for a short ride to the parts store with the IAB disconnected, and the car runs much better. I am doubting that there is any leaks in the intake tract due to the fact that it was fine before, but I also don't have the right tools to check for vacuum leaks or a decent place to work on the car now that we are in the process of moving our shop to North Carolina from here in Minneapolis.

I did the salt and pepper shaker FI plugs, and had the stock TB off in order to do that and install an aftermarket fuel pressure regulator. I also had the IAB off and cleaned the heck out of it and it was unbelievably dirty inside, also cleaned the TB, but when I put everything back together I am pretty certain there are no vacuum leaks, but of course I can't tell for 100% sure, but all the gaskets looked great and I just re-used them.

I did find that when I advance the timing, the RPM changes (goes up) at which the engine decides to hang when in/out of gear and rolling.

What would be the downside (if any) of just leaving the IAB disconnected for now? Should I try a new IAB?

Take a look at the EEC and see if it's an auto version or a manual version.
As soon as I finish this post I am heading outside to verify that it's got the original auto computer in it still.

Two other things that stick out to me as well that may be an issue is the VSS as was mentioned before, but I don't think that's it.
Yeah, I don't think that's it either, as EVERY time I come to a stop, the RPM's come down like they should...and it's much quicker/better behaved with the IAB disconnected.

The other being where you are getting your 1600RPM value from. If it's off the stock gauge it's probably wrong, the stock tachs are known to have issues with keeping the exact RPM displayed and can often times be off by 400 RPM.
Yes I have all stock instrumentation, I'm just going by the stock tach. I think I might try another ride after bumping the timing back up to see what happens with the IAB disconnected.

So after this kinda rambling-all-over-the-place post, does it sound to anyone else like I may just need a new IAB valve? Thanks in advance people...

EDIT: I am pretty sure I have the stock auto computer, it says A9P. Also, went for a ride with IAB disconnected after bumping the timing and it's the same thing as when IAB is still connected...when I bump the timing, the idle hangs higher. Argh! I *know* this car did not have any of these issues when I owned it previously.

I am going to try the idle reset tactics (listed below) suggested by Harvester of Sorrow earlier in this thread and will report what happens...also found out that the Ford Dealer wants $125 for a new IAB, sheesh. So, I seem to be back at square one assuming the idle reset thing is going to fail...any ideas?? I am almost positive that I'll be getting the Tweecer system in the near future which as I understand it will probably fix all of this, but dang it I want it to work the way it's supposed to NOW with what I've got! Help?

Harvester of Sorrow:
"have you guys reset the idle memory. i had this problem & resetting the idle strategy worked for me & its been more than a year now. its goes something like this:
1. disconnect negative battery cable for 20. min. or so
2. unplug the i.a.b solenoid connector
3. after said time has gone by, reconnect battery cable & start the car. under the T.B. there is a set screw to adjust idle-set it to where you want it [ about 700-850rpm is good]
4. after car is running, let it run for 2-5 min. & shut it off.
5. reconnect the i.a.b solenoid connector & again let run for 2-5 min. & shut it off.
6. restart car & turn ALL accessories on & let run 2-5 min. & turn off.
7. take it for a drive & get back to us. this worked great for me.
FYI - i had to do this a few times to get it right so stick w/ it!"
 

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Discussion Starter #206
Zeke,
Are you reseting the timing with the PIP disconected and then reinstalling after you bump the timing?

Wes
 

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I remove the the plug, start the car and adjust the timing, shut off car and reconnect plug, then start car again.

The "timing reset trick" seemed to have helped at first, but now I think it's just that I put the timing all the way back to stock.
 

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great thread here. im going to look under the hood now and try to locate where the ten pin connector is. does anyone have a recent pic of where its located? my car also idles slightly high, and i adjusted the tps to the max but it still idles around 1k rpms.. and the idle does hang up a little after putting in the clutch. also, when sitting in the car while it is idling ever 6 seconds the idle will drop a hair and then pick back up.. its very consistant with every 6 seconds. any ideas? the car seems to run fine, but making it even better is always a good thing.
 

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I FOUND THIS

Is this any help? What are they talking about and where is it?

There is a device called the Hot Idle Compensator that could be bad. It is not computer controlled so the computer will have no idea if it is good or bad.

The hot idle compensator cools the engine during hot idle operation. The compensator may be integral or mounted separately. When open, the compensator bleeds air into the manifold, leaning out the air/fuel mixture at idle. This increased air intake causes an increase in engine idle speed, resulting in cooling of the engine. Temperature rise on the bi-metal sensor lifts the normally closed valve and opens the air passage. A valve that does not fully close will cause high idle speed and excessive exhaust emission.

WHile the engine may not actually be hot, over time the bi-metallic sensor does go out of spec and may open too soon, causing the problem you describe.
 

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Is this any help? What are they talking about and where is it?

There is a device called the Hot Idle Compensator that could be bad. It is not computer controlled so the computer will have no idea if it is good or bad.

The hot idle compensator cools the engine during hot idle operation. The compensator may be integral or mounted separately. When open, the compensator bleeds air into the manifold, leaning out the air/fuel mixture at idle. This increased air intake causes an increase in engine idle speed, resulting in cooling of the engine. Temperature rise on the bi-metal sensor lifts the normally closed valve and opens the air passage. A valve that does not fully close will cause high idle speed and excessive exhaust emission.

WHile the engine may not actually be hot, over time the bi-metallic sensor does go out of spec and may open too soon, causing the problem you describe.
Not sure where you got this info, but Mustangs have an IAC....mounted on the throttle body.
 

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i did the IDLE RESET tonight on my buds 91 coupe and it runs like a new car now !!!

i am gonna check out the salt and pepper shakers and see if that makes it even better.

87 octane , 20* of timing and it runs like a raped ape
 

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Good thread. But I have found something weird with my idle.after driving my idle sticks between 1500-2200 with the clutch in. I have found if I shut the ignition off, and restart. (even turning the ign off while rolling and turning key back to the on position [not engaging the starter] it instantly idles back to normal.) I found I can do this fast enough that the engine never really stops running. Obviously this has to do with me "restarting" the computer. Wouldn't that indicate a eec problem?

ALso about a year ago I removed the extension harness, my idle problem went away for about 6 months, and it has been back ever since. Anyone think this may be a computer issue?
 

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Hello all, I have a very nice, <30k mile 87 mustang LX 5.0 with a 5 speed. Car is 100% stock but it does have this issue where, after the car is warm and up to operating temperature, when I push in the clutch to shift, the idle "hangs" and is very slow (if at all) to come back down. And when the car is stopped, it isn't unusual for the car to idle around 1800 RPM. It comes and goes though. If I stop the car and restart it, it seems to go away for a bit and then will come back. Also, not sure if this has anything to do with it, but it seems like the car may be a bit "under powered". I'm not expecting a 3 second 0 - 60 or anything but should I expect the rear wheels to break loose when I nail the gas pedal from a stop or maybe 10 MPH? I'm not an auto mechanic; I work on 2 stroke dirt bikes, not cars. Does this seem like a faulty TPS, or O2 sensor, or something else? I hesitate to take the car to the local ford dealer and give them a blank check. Any advice would be much appreciated. Thanks!
 

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check for both sets of codes first
 

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Back agian, :D

1. Disconnect the battery

2. Take apart the 10 pin connectors.

3. Get a small nail and slightly crimp the female side of the connectors, this will help tighten the connectons. Do this on the complete assembly.

4. Put dielectric grease on the male side of the connectors
and reassemble.

This is the fix for a stuck/high/surging idle. Example: You pull up in the driveway or to a stop light with the clutch in and the car idles it self up to 2K or 3K rpms and then stays there, then finaly drops down when it wants to. Or, your driving down the road, push the clutch in, and the car stays at whatever rpm you were at when you went to make the shift for more than a sec or two.

The 10 pin connectors are black and white plastic connectors that go between the main wiring harness and the fuel injector harness. They are located at the firewall end of the intake. I will try to find some pics and post them.

And you all thought this thread was dead.

Wes

EDIT:http://66.96.130.106/archives/2002/01/tenpin/
EDIT:Cleaning TB and IAB

EDIT(1/18/03) There is quite a debate about setting the tps at .98v or .97v or what ever, well. Set your voltage at .93v and enjoy. The info below is being posted because other than the voltage value given, it is pretty much dead on.

How To Adjust TPS
"Muscle Mustangs & Fast Fords"
April 1993
------------------------------

The throttle position sensor is one of those things that falls
into the category of "computer stuff" that makes a big difference
and is easy to deal with, but average people like us would never
know about. Without the proper adjustment, the throttle position
sensor (TPS) will give the computer a false reading as to the
exact throttle opening. A false reading will limit wide open
throttle performance (something we definitely don't want). A
voltage reading must be taken using a digital volt/ohmmeter
(DVOM) with the Key On/Engine Off and with the Key On/Engine
Running. A Radio Shack DVOM, part No. 22-185A, works well for
this job.

The TPS is located directly on top of the throttle body and is
adjusted by loosening the two phillips mounting screws and
swiveling the sensor until the highest reading is found. It may
be necessary to elongate the holes with a small file to achieve
the desired reading.

The spec range for Key On is from .88 to 1.0 volt; shoot for the
.97 to .99 volt. With the engine running, the voltage should be
no higher than 1.05 volts.

Incorrect Throttle Position Sensor (TPS) voltage will result in
reduced performance. The best way to take a TPS voltage reading
is by using two safety pins through the wires coming from the
sensor. The positive lead is attached to the green wire, while
the negative goes to the black wire. Always ground the meter
through the sensor's black wire. This gives a direct, and more
accurate ground into the computer.
I
 

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I have a 85 mustang with a 5.0 TBI.I know everyone would recommend to throw set up away. But I’m gathering parts for a sefi set up. Does this also work on my set up ?
 

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you see the date of the post?

start a new thread, with a clear and concise question you have
 
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