idle problem

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wtjames06

New Member

Jul 25, 2006

6

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0

Dec 21, 2006

#1

• Dec 21, 2006

• #1

i have a 91 gt with a fresh motor,vortech sc,cobra intake,afr heads b303 cam,new injectors,throttle body,and mass air...my question is this,when i first crank the car the cam sounds great,idles at 6 to 7 hundred rpms but after i drive it and it gets good and warm it idles at around 8 to 9 hundred rpms and sometimes ides up to 1000 to 1100 rpms then settles back to around 8 or 9 hundred again, you really cant hear any cam lope...and that sux,i took it back to my mechanic and he claims he did some adjustments but it still sounds and idles the same to me,any ideas on whats wrong? or does this sound like normal operation?....thanks

 

tording

Founding Member

Nov 11, 2000

164

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0

Hampton, VA

Dec 21, 2006

#2

• Dec 21, 2006

• #2

Well the B303 ford cam is not that big of a cam and I am pretty sure it has a 114 lobe seperation which is what causes "lope". The surging idle is pretty typical of a car with an aftermarket cam. You can do the computer/idle reset to try and take care of it but I doubt that without a tune you will get it to go away completely.

 

89streetbeast

New Member

Dec 4, 2006

365

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horton,ks

Dec 21, 2006

#3

• Dec 21, 2006

• #3

sounds like your iac valve may need cleaning or replaced. i'd clean it first to see if it works. just my .02

 

JChalfan

Member

Nov 27, 2002

551

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16

Bellevue, WA

Dec 21, 2006

#4

• Dec 21, 2006

• #4

You could unplug your IAC and see if the idle drops back down to where it should be. I had an E303 cam in one of my old cars, and I never could get it to idle correctly with the IAC hooked up. I ended up just disconnecting the IAC, which I don't recommend since it will make it hard to idle when it's cold or you turn on the A/C or defrost.

In my case the IAC wasn't sticky, the computer was just telling it to raise the idle for some unknown reason. I'm sure there was a proper fix, I just never looked into it.

Jeff

 

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wtjames06

New Member

Jul 25, 2006

6

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0

Dec 21, 2006

#5

• Dec 21, 2006

• #5

it has a proper tune,1000 $ worth of dyno actually,i guess ill call the shop today and see if they replaced the iac if not i guess ill start there,like i said erlier,a cold start it sounds great,nice chunky lope,but after the warm up you can barely hear the cam,just seems like it would be a simple fix...

 

89streetbeast

New Member

Dec 4, 2006

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horton,ks

Dec 21, 2006

#6

• Dec 21, 2006

• #6

usually iac's when they are bad you can tell after the engine either comes down from fast idle start or when the motor is slightly warm. ford trucks are really bad on that. i'd take the 2 bolts out that hold it on and look inside the iac and see if theres a bunch of carbon buildup on there. if its full of carbon you could either clean it or buy a new one. cleaning is only a temp fix but then you'd know if it was that or something else

this thing really comes in handy also http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=LRS-9939A 1&comp=LRS

 

Flavadave4

Active Member

Nov 28, 2003

1,044

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Utica, NY

Dec 21, 2006

#7

• Dec 21, 2006

• #7

Clean the IAC......if it fixes the problem it willonly last fr a while but at least you will know what wa throwing the idle off.

 

jrichker

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Mar 10, 2000

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Dublin GA

Dec 21, 2006

#8

• Dec 21, 2006

• #8

See "Help me create the Surging Idle Checklist" at http://forums.stangnet.com/showthread.php?t=534062
for help with your idle problems. The first post contains all the updates to the fixes. I continue to update it as more people post fixes or ask questions.

Ranchero50's comments in the tech note might be just what you are looking for