choppy idle when cold-- where to start?

93GTDIN · 02-26-2004, 11:57 AM

Ok guys, friend of mine is having probs with his 5.0. It's basically stock, exhaust, gears, pulleys, no other engine mods. When he starts it up (worst in cold weather) It idles pretty eradically, but eventually smooths out. It never gets quite as smooth as a stock 5.0 should be. So my question is, what do I check first? a list of things to check, in order of most likely culprit would be excellent.

Also, i know one of the most commonly mentioned things will be the IAC. How does one check the IAC for functionality?

Thanks,

Dino

richd · 02-26-2004, 03:41 PM

Sorry, I hit submit by accident....

richd · 02-26-2004, 03:46 PM

Start in a warmer place! j/k

Start by checking for vacuum leaks. I think you can spray carb cleaner on vacuum lines to do this, but I'm not sure how safe that is. The idle will rise for a sec when you hit a vac leak.

Then I'd recommend removing the whole throttle body assembly and cleaning it. Take out the throttle plate, take apart the IAC and spray the crap out of everything with carb cleaner (and a rag).

Adjust the idle according to the following:

1. Back out the throttle plate stop screw (it should not contact the pad).
2. Turn in stop screw until .010 in from pad (use a feeler).
3. Turn in an additional 1 1/2 turns.
4. Reset ECU by disconnecting battery.
5. Run engine for 2 minutes without throttle input
6. goose throttle (letting it return to idle)
7. lightly press gas and return to idle

That should reset your idle.

Good luck,

Rich D.

GhettoPop · 02-26-2004, 10:06 PM

http://www.corral.net/tech/maintenance/idlereset.html

02-26-2004, 11:57 AM	#1
93GTDIN Registered Member Join Date: Jan 2001 Location: Live music capital of the world, TX Posts: 324	choppy idle when cold-- where to start? Ok guys, friend of mine is having probs with his 5.0. It's basically stock, exhaust, gears, pulleys, no other engine mods. When he starts it up (worst in cold weather) It idles pretty eradically, but eventually smooths out. It never gets quite as smooth as a stock 5.0 should be. So my question is, what do I check first? a list of things to check, in order of most likely culprit would be excellent. Also, i know one of the most commonly mentioned things will be the IAC. How does one check the IAC for functionality? Thanks, Dino __________________ 96 Cobra - a bit too stock. 14.0 @ 101

02-26-2004, 10:06 PM	#4
GhettoPop Gimme a Drink! Join Date: Dec 2002 Location: NYC Posts: 694	http://www.corral.net/tech/maintenance/idlereset.html __________________ 1990 GT,stock T-5,K&N w/o air silencer,March underdrives,FMS wires,timing@14*,PA Perf 130amp alt,Steeda Tri-Ax Shifter,Steeda adj quadrant/clutch cable/firewall adj,Centerforce II clutch,o/r x-pipe,Magnaflow SS catback,g-load brace, subframes,Bilstein struts/shocks,Autometer gauges, 136k and running strong!

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02-26-2004, 03:41 PM	#2
richd Registered Member Join Date: Jul 2001 Location: Edison, NJ, USA Posts: 125	Sorry, I hit submit by accident....

02-26-2004, 03:46 PM	#3
richd Registered Member Join Date: Jul 2001 Location: Edison, NJ, USA Posts: 125	Start in a warmer place! j/k Start by checking for vacuum leaks. I think you can spray carb cleaner on vacuum lines to do this, but I'm not sure how safe that is. The idle will rise for a sec when you hit a vac leak. Then I'd recommend removing the whole throttle body assembly and cleaning it. Take out the throttle plate, take apart the IAC and spray the crap out of everything with carb cleaner (and a rag). Adjust the idle according to the following: 1. Back out the throttle plate stop screw (it should not contact the pad). 2. Turn in stop screw until .010 in from pad (use a feeler). 3. Turn in an additional 1 1/2 turns. 4. Reset ECU by disconnecting battery. 5. Run engine for 2 minutes without throttle input 6. goose throttle (letting it return to idle) 7. lightly press gas and return to idle That should reset your idle. Good luck, Rich D.