Idleing and rev probs

M0T0PSYC0 · May 11th, 2008, 11:46 PM

hi guys new to this board and its my first post here, but I figure someone may know what this problem might be.
After the car warms up when I stop at a light, sign or in the driveway, the car idles down and almost dies, then it jumps up to about 3 grand then does it again. Anyone know what this could possibly be, I have no engine light coming on so theres no codes thrown. the car is a 99 mustang gt, 5 speed. There is a couple mods, its has k&n fipk 2 cai, and 3.90 gears, i really dont think either of that has anythingto do with it, but other than jumping at idle the car runs great. Also in case this helps there is a new sensor bolted the the front of the upper intake that has been replaced, maybe needs adjusting? I just bought the car aweek ago. it only has 133k miles on it so it shouldnt be anything major at all. just need some ideas what to check out, and thanx in advance guys, and if you need more info i willbe checking here often, and start doing some posting as well.

'02SilverBullet · May 12th, 2008, 10:35 AM

Not real sure.... maybe the IAC needs cleaned. My car has done the higher than norm idle but it never went way down and almost went dead before. It was cuz my IAC was dirty. Cheap to check though. Get ya some carb cleaner and take it off and clean it up inside and bolt it back. Thats the only thing I can think of right off hand.

Arctic Fox · May 13th, 2008, 12:06 PM

Vacuum leak could do that also. Check the changed sensor in manifold specifically, maybe it isn't tightly in place.

TurboLX · May 13th, 2008, 01:29 PM

+2 on the IAC

M0T0PSYC0 · May 15th, 2008, 04:16 AM

well the changed senor in the manifold is the iac. I didnt clarify that clearly before, looks pretty damn new (very shiny, taken it off and no buildup of anything in it). just doesnt make much sense to me why it would act like this and something that gets continously worse too. other than that the car runs great but likes to buck for first and second and a little in third if i give it more than easy take off acceleration. Its very annoying cuz other than the whole wanting to die then revving up and draw attention, then it bucks around making me look like someone who hasnt ever driven a stick before, so it gets kinda embarrasing to even drive around town. Also I do have a second IAC to bolt up and check out tomarrow to see if that is the case, if it acts the same its gotta be something else.

May 11th, 2008, 11:46 PM	#1
M0T0PSYC0 Regular 1999 Mustang GT 13.8 Join Date: May 2008 Location: Otsego, MI Posts: 54	Idleing and rev probs hi guys new to this board and its my first post here, but I figure someone may know what this problem might be. After the car warms up when I stop at a light, sign or in the driveway, the car idles down and almost dies, then it jumps up to about 3 grand then does it again. Anyone know what this could possibly be, I have no engine light coming on so theres no codes thrown. the car is a 99 mustang gt, 5 speed. There is a couple mods, its has k&n fipk 2 cai, and 3.90 gears, i really dont think either of that has anythingto do with it, but other than jumping at idle the car runs great. Also in case this helps there is a new sensor bolted the the front of the upper intake that has been replaced, maybe needs adjusting? I just bought the car aweek ago. it only has 133k miles on it so it shouldnt be anything major at all. just need some ideas what to check out, and thanx in advance guys, and if you need more info i willbe checking here often, and start doing some posting as well.

May 12th, 2008, 10:35 AM	#2
'02SilverBullet Regular Join Date: Nov 2007 Location: Memphis Posts: 124	Not real sure.... maybe the IAC needs cleaned. My car has done the higher than norm idle but it never went way down and almost went dead before. It was cuz my IAC was dirty. Cheap to check though. Get ya some carb cleaner and take it off and clean it up inside and bolt it back. Thats the only thing I can think of right off hand. __________________ Mods.. BBK CAI MM Caster Camber Plates Baer Decalla Drilled and Sloted Rotors w/ painted callipers Hypercoated 18x9 FR500 Rims Eibach Pro Kit Lowering Springs More to come.....!

May 13th, 2008, 01:29 PM	#4
TurboLX MM Ninjas! 1990 Mustang LX Turbo 8.675 @ 165.91 Join Date: Oct 2006 Location: New York Posts: 7,925	+2 on the IAC __________________ (Wiring Diagrams For ALL Mustangs And OBDII/Generic DTC Available. PM For Info) FORD 2.3 FORUMS

May 15th, 2008, 04:16 AM	#5
M0T0PSYC0 Regular 1999 Mustang GT 13.8 Join Date: May 2008 Location: Otsego, MI Posts: 54	well the changed senor in the manifold is the iac. I didnt clarify that clearly before, looks pretty damn new (very shiny, taken it off and no buildup of anything in it). just doesnt make much sense to me why it would act like this and something that gets continously worse too. other than that the car runs great but likes to buck for first and second and a little in third if i give it more than easy take off acceleration. Its very annoying cuz other than the whole wanting to die then revving up and draw attention, then it bucks around making me look like someone who hasnt ever driven a stick before, so it gets kinda embarrasing to even drive around town. Also I do have a second IAC to bolt up and check out tomarrow to see if that is the case, if it acts the same its gotta be something else. __________________ 99 forrest green vert: -Diablosport Predator & Tune -K&N FIPK II CAI -Motive 3.90 gears -Mac o/r H -Flowmaster American Thunder catback -Eibach Sportlines -Tokico D-Spec shocks & struts My Garage Last edited by M0T0PSYC0 : May 15th, 2008 at 04:20 AM.

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