95 5.0 Won't Idle Down Quickly Enough - Ford Mustang Forum
 
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post #1 of 11 (permalink) Old 02-08-2012 Thread Starter
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95 5.0 Won't Idle Down Quickly Enough

After replacing the idle control valve and mass air flow sensor the CIL is now off, but the motor wants to idle at about 1,500 rpm while decelerating. It will finally go on down to 1,000 rpm, but wants to run for several seconds after the accelerator is up.

Have I read where something needs to be calibrated? Is is something a yard mechanic can do? Help!

Thanks, in advance!
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post #2 of 11 (permalink) Old 02-09-2012
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Mine started doing a hovering idle after I cleaned my IAC. I had a few other vehicles that did this as well. Apparently, it was to make for smoother shifts (people that don't know how to rev match for gear changes?)

Either way, I've always assumed it to be normal. Has yours always done it?

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post #3 of 11 (permalink) Old 02-09-2012
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Dashpot setting in computer.Tied in with the VPS circuit.If the rpms drop down after the vehicle stops completely(1-2 seconds) then it is normal.If it takes longer than that,then it probably needs to be set at dealer or tuner.
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post #4 of 11 (permalink) Old 02-09-2012
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Not sure if your problem is the same as the problem i had. My car would idle around 1200-1500 rpm from startup and take a very long time to go from the 1500 area back down to 850ish. I resolved this problem by resetting the base idle. Takes like 10 minutes. Ford Mustang Base Idle Reset
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post #5 of 11 (permalink) Old 02-09-2012
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Originally Posted by StanG122 View Post
Not sure if your problem is the same as the problem i had. My car would idle around 1200-1500 rpm from startup and take a very long time to go from the 1500 area back down to 850ish. I resolved this problem by resetting the base idle. Takes like 10 minutes. Ford Mustang Base Idle Reset
+1^

Does your car have an aftermarket cam? Some cams simply idle higher.
On a cold start, its normal for the idle to be slightly raised to get the oil flowing, etc. I'm guessing your car is a 5-speed? With my auto in park/neutral it will sit around 1000~. In drive it sits at 700-800~ so your observations aren't a whole lot different from mine. If you can't fix it with the link above or anything else, I would invest in a true oil pressure gauge. The stock gauge is somewhat of a dummy gauge, it reads normal as long as you have above 6psi and doesn't measure the true pressure. Your oil pump may be dieing causing your car to idle higher to keep the oil flowing. This is a worst case scenario, but something to keep in mind if nothing else works.

1998 GT - CAI, trickflow intake, 3.73 gears, O/R x-pipe, flowmasters, short throw shifter, 24lb injectors. 155k miles
1995 GT vert - 1 of 36 5.0 Appx. 400,000~ factory motor miles (totaled, in garage)
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post #6 of 11 (permalink) Old 02-09-2012 Thread Starter
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It's a stock motor, automatic, and it didn't do this before I replaced the parts.

It's pretty annoying when you're pulling up to a stop light and having to really get onto the brakes and then the rpm falls.... You have to scrape yourself off the windshield! It's also a problem when trying to drive under about 40 mph. It won't go under that until the rpm's drop.

I haven't had a chance to look at it. Probably will tomorrow.

Thanks, all, for the feedback!
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post #7 of 11 (permalink) Old 02-15-2012
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Iac gasket on eBay they have a rubber one with smaller holes in a 5 speed. Empathy would drop to fast just take it off and cut tiny bit bigger and reinstall. I did that to mine to drop faster or the adjustable type cost more though. The rubber was like4.00 shipped.
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post #8 of 11 (permalink) Old 02-16-2012
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Quote:
Originally Posted by Hut View Post
[...] when trying to drive under about 40 mph.
There's your problem. :p

"Oh Good, my Dog found the Chainsaw"

'95 Mustang GT, 5 speed, O/R H-Pipe
Current Needs to Polish this Turd:
-AC Compressor
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post #9 of 11 (permalink) Old 03-06-2012 Thread Starter
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Is there a chance the idle control is the wrong one? Are they the same for 5-speed / automatic?

This is getting pretty annoying.... It was rather exciting with a little ice on the road a few days ago!

I may have to bite the bullet and have the demons (dealership) look at it. Then I'll have to float a loan....
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Quote:
Originally Posted by Hut View Post
Is there a chance the idle control is the wrong one? Are they the same for 5-speed / automatic?

This is getting pretty annoying.... It was rather exciting with a little ice on the road a few days ago!

I may have to bite the bullet and have the demons (dealership) look at it. Then I'll have to float a loan....
Just a shot in the dark. Has the throttle cable return spring come off or is it broken?

Richard
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post #11 of 11 (permalink) Old 03-07-2012 Thread Starter
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Just a shot in the dark. Has the throttle cable return spring come off or is it broken?
Everything seems to be intact.

My son has the car at college with him right now, but he's telling me it happens in about three differen rpm ranges. I'm still puzzled.
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