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Discussion Starter · #1 ·
Good morning All,
This is my first post to this forum and I hope I will find the help here that I thankfully get on a few other forums... Short and to the point, what is the correct procedure for clearing the codes in the ECU on my 1999 ford Escort SE wagon? If you want to do some reading with your morning coffee, please read on...
I have a 1999 Ford Escort SE Wagon that I got a few months ago and I have been chasing this problem ever since... I bought the 99 because we have a 1994 Wagon that has been a dream to own. It is and has been our family work horse. Anyway, soon after I got the 99 the SES light came on. I have access to a computer so I hooked up, got the error which was "idle air overspeed error". I changed out the IACV for a new one (from Ford), cleared the error and the light came on again real soon after. I asked my friend who works in a township garage taking care of all the town vehicles, to take a look. He changed out a suspect vacuum hose and cleared the code. Light came on again :x . He fixed a suspect connector pin, cleared the code, light came on again 8O . He fixed a suspect crimped wire, cleared the code, light on again :eek: . He also worked on another guys Ford with a similar issue and his light keeps coming back on. The other guy took it to a repair shop and the guy there, said everything is fine but to clear the code, you have to run the car for 2 hours, then clear the code. The light has not come on again for this guy. Do you know if this is true? Thank you for your reply.

Justrfb
 

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There are two ways to clear codes:

1. Erase the code from the flash ROM module on the ECU with something similar to an OBD-II code scanner (they usually have the wipe function built in).

2. Discharge the hot wire to the ECU. (disconnect battery terminals, discharge system).

The error codes are stored in a RAM type module, and the archetecture of ram necessitates power being fed through it constantly to maintain the information stored within.

However, the problem you're having is not "clearing" the code. You've already cleared the code several times. The problem is that the CEL (check engine light) keeps coming back on because the sensor is getting a bogus domain reading.

In other words, you've cleared the code, but the CEL will continue to flash because you really haven't fixed the problem at all.

I'm not sure exactly what the "idle air overspeed error" is, but I can tell you a bit on how the idling system on the escorts work.

The first question I have for you is- how is your engine running at idle? Does it idle high or low? When it's warmed up, do you still have idle problems?

The thing is, if you think about an engine, it only "sees" its world through a network of transducers. Therefore, if you do something like replace a vacuum hose - whoop de doo, you've fixed a vacuum hose - the real trick is finding out HOW replacing that vacuum hose affects how your ECU reads the sensors.

If you can ask the technicians at the ford place if they can look up a little more information about the error code you're getting, I may be able to help you out. The haynes manual isn't that good once you get beyond where you are right now.
 

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Discussion Starter · #3 ·
Thank you siragan for your reply...

I understand what you are saying about clearing the code but what I was told is that to clear the code on the "new" ECU's is not done by cutting the power to the unit. The information is stored in "NOVRAM", meaning the code stays without power supplied. Anyway, to answer your questions... The car runs and operates perfectly normal except for maybe, a higher than normal idle, lasting for a few seconds, when car is started or when car is put in Neutral or Park after being in a forward or reverse gear. There is no rough or high idle at all. This is the frustrating part about it. If I had an actual problem, it may help me to figure the solution out. Thanks again for your reply and any further assistance is greatly appreciated. I am "Stumped" with this one...
 

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Ah yes, you've got a 3rd gen, of course. Forgot about that.

In that case, probably the only way to clear codes is through a specialized device, like a fancy code checker. We've got an advanced auto parts in potsdam and they'll do that stuff for free for you. I'm not very familiar with the 3rd gen escorts, so you'll have to bear with me.

I did a little research on your problem and made a few calls and here's what it means:

Your ISC valve is in charge of electronically controlling the idle (of course). The error basically means that the ECU is not capable of bringing the idle down to where it was programmed to be. That basically means that the ISC valve can only go so far (completely shut), and after the ECU makes it do that, it's STILL idling high.

So here's how to fix it:

-Make sure that your throttle plate stop screw is set to where the throttle is completely shut.
-I dunno if the 3rd gens have an air bypass screw on the TB (but every car I'e worked on does). Make sure you've got less air flowing through that. On the cars I've worked on, you have to screw the screw in (clockise of course). Stock settings on most cars is like a turn out. To find yours out, count the number of turns it takes for it to hit the bottom, then record it in the back of your owner's manual (this is what I do). Either way, when you lower it, your ISC valve will start to back out and the ECU will start taking control of the idle rather than the bypass screw.

If that doesn't work, you can start to check the TPS voltages and compare them to the spec ones (which I don't have in my manual).

G'luck!
 

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Discussion Starter · #5 ·
Thank you again Siragan.

Your suggestions all sounded great to me so at lunch time (I am at work) I went out to my car, raised the hood, and much to my dismay, there is no by-pass air screw adjustment on, or near the TB. There is a solid threaded stud that looks like it could adjust the minimum stop position of the throttle plate but there is no by-pass adjuster. Maybe another "3'rd generation" (didn't even know this is what I have) owner could verify my claim. Thanks for your help. I appreciate it because, like I said, this one is getting the best of me...
 

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Sometimes they hide it underneath rubber caps or something.

In the 2nd generation escort GT VAMs, mazda went as far as to hide the bypass screw underneath a metal cap which needed to be drilled through :eek:

Sorry I can't help ya there. Maybe if you can shoot me a pic I can help ya out. :-\
 
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