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Discussion Starter · #1 ·
There is no SES, but the damn idle runs to 2300 -2500 at start up and then comes down during the 1st minute. If I forget to wait, it can get pretty rough on the tranny as it drops into gear. Where do I start to problem solve this? Thanks.
 

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2500 is not normal. Fast idle should be 1500 to 1800 max.
 

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2500 is not normal. Fast idle should be 1500 to 1800 max.
:werd:

Go wack the IAC with the head of a screw driver, see if the idle drops as soon as you make contact.
 

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^^^^ +1

Sounds like dirty / sticking IAC to me.
 

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Discussion Starter · #6 · (Edited)
Yeah, the is NOT normal. We have owned the car since new and the idle explodes to 2300 as soon as it kicks over . When it is freezing outside, that can't be good. It does it on 70 degree days as well. How do I clean the IAC or is it cheap to replace? Thanks.
 

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New IAC runs about $50 to $60 at Rockauto, double that at a dealer. Amazon might have them too... never checked.

To clean, remove it (2 8mm bolts) and blast it out good with brake cleaner. Reinstall. If old gasket rips, make a new one out of thin cardboard (6 pack container). Sometimes cleaning works, sometimes only replacing it works.
 

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** EDIT ** OP Has a 1998
Is your car long cranking in the morning when you go to start it ? There was a TSB related to your vehicle for ECU reprograming if it is. Cleaning your IAC is a good thing I clean mine every 15K along with the MAF sensor. See the attachment.

FWIW My 2000 on cold start-up goes to about 2000 and then drops to about 1800 after 2-3 seconds.
 

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There is no SES, but the damn idle runs to 2300 -2500 at start up and then comes down during the 1st minute. If I forget to wait, it can get pretty rough on the tranny as it drops into gear. Where do I start to problem solve this? Thanks.
Mine does the same in "P". But as soon as I put it in "D" (with the break pedal depressed), rpm's go down to 750.
I replaced recently the Neutral Saftey Switch (Transmission Range Sensor) with one from salvage yard and the new one does this. Measured the internal resistance and the "P" is same with the "R".
My old one wasn't doing this at start (high rpm), but had other major problems - wasn't signaling the "D" position properly whan was cold (and the car was staying in 1st gear).
 

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Discussion Starter · #10 ·
Does anybody have a part number for the IAC for a 98 taurus with dohc? Also is a called an "idle speed control"?
 

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Dunno. Just get a borg-warner one for your make/model from advance auto or oreilly. Idle air control valve. Bwd part#28942. Get it from adv. auto for $58. Same part# is $97 at oreilly? Dont know why the discrepancy?
 

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Discussion Starter · #12 ·
I tried wacking the IAC while it ramped up to 2300 and that did not drop the idle. But, I unplugged it and the idle dropped right down. I have no codes. What else could it be if not the IAC? Thanks.
 

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Have you removed it and tried cleaning it with throttle body spray cleaner or brake cleaner? Ive never had a code with a faulty iac either. Mine, when bad, have usually surged up and down. Possible high idle causes: vac. leaks, iac, tps, maf, iat, ect and ps pressure switch.
 

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Yeah, I'm having a fast idle problem as well. It jumps to 1800 immediately but unlike the OP mine doesn't seem to drop unless I give the engine a bit of gas, in which case it then comes back down to around 1800 immediately after lifting off the peddle before very slowing dropping to around 950 or so.

After a bit of driving, idle RPM drops around 500 or so.

IAC as well?
 

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I have a 2000 taurus dohc and my idler speed is 1100 rpm and it run great . I change the IAC and it ran even better . I have 250,000 mile and it don't use any oil the key is maintaning proper check-up . O'reilly , autozone , advance auto carry that part and it run about 50-60 dollar. I hope this help . My last car was a 1996 taurus and it ha 450,000 mile before I sold it and it ran good.
 
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