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Discussion Starter · #1 ·
New member- purchased a 2004 sprectra for commuting. Runs well with one issue: the engine revs slightly when the clutch has been depressed during upshifts. It doesn't seem to do it during downshifts. When throttles are manipulated manually, it doesn't return to idle as quick as I think is proper.

any help is greatly appreciated.:)
 

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99 Kia Elan 1.8L
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Welcome to the forum.

It sounds like the Idle Speed Control (ISC) valve is sticky - most often this can be corrected by taken it off and cleaning with carb cleaner.

ISC often referred to as Idle Air Control (IAC) valve.
 

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Discussion Starter · #3 ·
Thanks for the suggest on idle speed control valve.

I've been trying to set up account on KiaTechInfo but I'm not having any luck. After filling out form I click on the link to agree to privacy and usage. I click the box and close the page. Then I click to establish an account and it gives me a message to review the privacy and usage page. Any suggestions?

once I can understand where the valve is, my carb cleaner and I are ready clean it up.
 

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Follow the large black rubber air hose back to an aluminum "tube".
Remove the hose and look inside...Thats where the IAC butterfly is located.
Clean the throat and the butterfly and check that it moves freely.
Dave
 

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Discussion Starter · #6 ·
Thank you both for your suggestions. Sadly I am still unable to get an account for the Kiatech.com. The only thing I haven't tried yet is the compatibility mode, Explorer 8. I'll give that a whirl and let you know.

Dave- I had the air inlet piping off yesterday. The throttle body inlet flap seemed to have no issues in play or any build up etc when manipulated directly. When throttle cable manipulated directly, engine off, it came right back as it should. Has a hitch in its get along when engine is on.

Where is the idle control valve located on the throttle body?

thanks again for your help, I greatly appreciate it.
 

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99 Kia Elan 1.8L
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The ISC valve passes air around the closed throttle butterfly valve.

There's two devices with wiring attached on the throttle body, one is inline with the butterfly valve shaft, and that is the position feedback sensor, and the other one is the ISC.

If you turn the ignition on, listen and feel for the one that buzzes just a little, and that is the ISC.

Attached is a picture of the ISC from my car - yours might be the same or similar.


 

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Cerato
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New member- purchased a 2004 sprectra for commuting. Runs well with one issue: the engine revs slightly when the clutch has been depressed during upshifts. It doesn't seem to do it during downshifts.
Doesn't sound like a big problem. Can you overcome it by altering clutch technique?

When throttles are manipulated manually, it doesn't return to idle as quick as I think is proper.
Do you mean pressing the accelerator while in neutral?

KIA Site is notoriously difficult to access.
 

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Discussion Starter · #9 ·
hi again,

well took off what I think is the ISC, cleaned the very end of it and replaced it. Sadly I also removed the throttle position sensor and replaced it. So...

solved the issue with the motor reving when clutch depressed during gear changes BUT caused something else.

Motor now acts and sounds like it is running rough. When cold it will rev high by itself and then come back to regular idle. Under acceleration no issues, all 4 humming along. Under steady state throttle is acts like it is stumbling, kinda surging etc.... At idle exhaust sounds like it is slightly out of time. I:

rechecked all hoses
rechecked plug wires
cursed myself for having touched the throttle position sensor which I suspect is now the issue.:(

All thoughts suggestions greatly appreciated.
 

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99 Kia Elan 1.8L
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Take a look at the KiaTech web site for the instructions on setting the TPS - its important that this is done, unless you clearly marked it before taking it off.

Have you cleaned the ISC yet ?
 

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Discussion Starter · #11 ·
I had cleaned the ISC, at least the end of the magnetic shaft. The shaft turns, but acts like the bearings in it are But now I'm back to zero.

I pulled out the pcv valve and cleaned it with carb cleaner. After reinstallation and without touching anything else, test drive.

Nuts car runs great again but the revving problem during gear changes is back. I'm going to clean the ISC again and try it one more time.

How would a plugged pvc hinder the operation of the ISC such that the revving problem goes away? AND if the second clean doesn't do it, would you suggest a new ISC?

:confused:
 

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Discussion Starter · #12 ·
cleaned the ISC very well and shaft now rotates freely. However, car still picks up revs while clutch depressed during upshifts. As much as 200 rpms. Not good for the clutch to engage under load.

any more suggestions or do I punt?
 

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99 Kia Elan 1.8L
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cleaned the ISC very well and shaft now rotates freely. However, car still picks up revs while clutch depressed during upshifts. As much as 200 rpms. Not good for the clutch to engage under load.

any more suggestions or do I punt?
I replaced an ISC on my own car that was clean, mechanically free to move and checked out good electrically - the new one solved the problem (similar symptoms to what you describe).
 

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Most certainly check for vacuum leaks, but generally a leak results in a constant high idle rpm.
i had almost the same issue with my spectra recently it will idle high for about 5 seconds after start up from it being warm already and sometimes will idle to about 2g then drop back down when i stop at the stop sign or light i looks at all my vaccum hoses and found one thes behind the intake manifold that had a big crack on it and i replaced that hose and no more funny idling.
 
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