weird idle problem

04MustangGT · 03-01-2006, 07:42 PM

My friends mustang after the install of the throttle body and plenium was way out of wack. The car seems to jump from 400 to 600 after start up. It idles really low and sounds like it is just about to die. But if you give it a little gas and let off the throttle it stays at 2000 rpm for about 30 sec or so, then drops back to idleing funny again. It sounds cool when idleing because it sounds like it could be cammed, but everytime we are at a stop after giving it gas it goes back up to 2000 rpm and it sounds like he is just holding the throttle at 2000. I have checked every thing around the throttle body and plenium and also put the stock one back on but no luck. His odometer also shuts off randomly when he is driving and the speedometer will just go to zero at the same time but every other gauge still works. I have no clue what is wrong with the idle problem or his guages. Any suggestions?

Stangdude27 · 03-01-2006, 07:50 PM

Doule check all your vacum lines and electrical conection incase you took something off. Then if you still have problems disconect the battery. Then remove you IAC and look for dirt. If dirty get some carb, or brake cleaner and spray it down. Then re install IAC and hook up the battery. Start car and check for idle drop off and raise. If it still idles rough adjust the TB to see if it will fix it. Also you might have to recheck for leaks around the TB. You could judt have a leak. Good luck

WaterDR · 03-01-2006, 09:04 PM

The base idle is set too low and it is "hunting". You just need to nudge the idle set screw up a tad and it should be fine.

trnin · 03-02-2006, 10:57 AM

yeah... i had the same problem.... just dink around with that screw till the idle rests @ about 800rpm

04MustangGT · 03-02-2006, 10:59 AM

on the 2003 mustang were is the idle set screw?

stanger00 · 03-02-2006, 01:33 PM

its on the trottle body.

03-01-2006, 07:42 PM	#1 (permalink)
04MustangGT Senior Member Join Date: Dec 2005 Posts: 354	weird idle problem My friends mustang after the install of the throttle body and plenium was way out of wack. The car seems to jump from 400 to 600 after start up. It idles really low and sounds like it is just about to die. But if you give it a little gas and let off the throttle it stays at 2000 rpm for about 30 sec or so, then drops back to idleing funny again. It sounds cool when idleing because it sounds like it could be cammed, but everytime we are at a stop after giving it gas it goes back up to 2000 rpm and it sounds like he is just holding the throttle at 2000. I have checked every thing around the throttle body and plenium and also put the stock one back on but no luck. His odometer also shuts off randomly when he is driving and the speedometer will just go to zero at the same time but every other gauge still works. I have no clue what is wrong with the idle problem or his guages. Any suggestions? __________________ 04 GT 5 spd Modifications: SLP Catback Exhaust SLP catted X-Pipe SLP Headers Pro 5.0 Shifter H&R Sport Springs Raptor Shift light, 17x9 & 18x10 Black Bullitts http://s26.photobucket.com/albums/c103/04MustangGT/ Soon To Come:4.10 Gears

03-01-2006, 09:04 PM	#3 (permalink)
WaterDR Administrator Join Date: Sep 2004 Posts: 6,374	The base idle is set too low and it is "hunting". You just need to nudge the idle set screw up a tad and it should be fine. __________________ Black 2000 GT Vert: Novi-2000 with Intercooler (375rwhp @ 9 psi); Tune by Kauffmans; Roush 380R Body kit; Steeda Subframes; Steeda Strut Tower Support; Deep Dish Bullets; FRPP 4:10's; SCT 4 Position Chip with four custom tunes; Steeda CAI; C&L Pleum; BBK 75 TB; SLP Loudmouth; SLP Catted X-Pipe; Bullitt Suspension; UPR Conrol Arms; Focus Fuel Pump My Car My Email

03-02-2006, 10:57 AM	#4 (permalink)
trnin Senior Member Join Date: Mar 2005 Location: rapid city sd Posts: 154	yeah... i had the same problem.... just dink around with that screw till the idle rests @ about 800rpm __________________ 2001 mustang gt, automatic C&L intake plenum helix throttle body & intake spacers mac throttle body k&n cai diablo predator tune slp loudmouth cat back tokico illumina shocks&struts tokico lowering springs 1.25 4.10 gears vcn 1000 nitrous 1964.5 mustang 55 thousand orginal miles on bone stock 260 v-8 all stock &midnight blue/caspian blue sold

03-02-2006, 10:59 AM	#5 (permalink)
04MustangGT Senior Member Join Date: Dec 2005 Posts: 354	on the 2003 mustang were is the idle set screw? __________________ 04 GT 5 spd Modifications: SLP Catback Exhaust SLP catted X-Pipe SLP Headers Pro 5.0 Shifter H&R Sport Springs Raptor Shift light, 17x9 & 18x10 Black Bullitts http://s26.photobucket.com/albums/c103/04MustangGT/ Soon To Come:4.10 Gears

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03-01-2006, 07:50 PM	#2 (permalink)
Stangdude27 Silver 2003 GT Conv Join Date: Nov 2004 Location: Ft Walton Beach,Florida Posts: 399	Doule check all your vacum lines and electrical conection incase you took something off. Then if you still have problems disconect the battery. Then remove you IAC and look for dirt. If dirty get some carb, or brake cleaner and spray it down. Then re install IAC and hook up the battery. Start car and check for idle drop off and raise. If it still idles rough adjust the TB to see if it will fix it. Also you might have to recheck for leaks around the TB. You could judt have a leak. Good luck

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