Irradic Idle

Comatose · 11-09-2001, 09:39 PM

I own an 86 GT 5.0 HO, 5spd.

The idle varies between 500-1100rpm--sometimes it holds relatively consistent, and other times it will surge between 700-1000rpm. Please Help

Capri306 · 11-09-2001, 11:03 PM

Clean out the idle air bypass valve, the ports it attaches to, and the throttle body & throttle valve (butterfly) with some good quality throttle body & air intake cleaner (STP makes some good stuff). Don't use regular carb cleaner. You might find a toothbrush a big help, especially if this is the first time you've done it. After that, check TPS voltage. You should have a consistent voltage of about 0.80-0.95V, without any variation or wavering, between the center wire on the harness and ground. You have a speed density EFI system, so resetting the computer and idle speed shouldn't be necessary as on later MAF systems. When's the last time you did a complete tune-up? This includes plugs, cap, rotor, wires, and possibly coil (TFI coils are so cheap, I replace mine if there's any doubt). If you want to, you may wanna have the ignition module checked by an auto parts store, just to be sure. Check your ignition timing while you're at it, too.

Okay, yeah, I'm a little obsessive about this, but I like my 'Stang to run well.

------------------
Capri306, Moderator, The Mustang Works Online

"PROUD TO BE AN AMERICAN!!!"

PKRWUD · 11-10-2001, 07:14 AM

After doing those very good suggestions, perform a self test in both KOEO and KOER modes and jot down any codes that come up. This will help isolate any equipment that is past it's prime and in need of replacement.

Take care,
-Chris

------------------
Retired Moderator
MustangNet

My site: Peckerwoods Pit Stop

My teams site: Jim Porter Racing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.

abesmith69 · 11-10-2001, 03:15 PM

all I did to fix my idle problem is disconnect the IAB for 5 minutes and then plug it back in, its worked fine!

Thanks,
Abe

------------------
1990 Mustang GT Convertible, Blue with Grey ground effects and white top. Black Leather interior pw,pl,ps,pm, premium sound system. All stock =(

Comatose · 11-10-2001, 06:44 PM

Thanks for the help....where is the IAB?

I just bought this car two weeks ago and I'm not very experienced with EFI. The car had a complete tune-up before I bought it--new plugs, cap, rotor, wires, exhaust, etc,etc.

abesmith69--Did you unplug it while it was running?

Thanks

11-09-2001, 09:39 PM	#1
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	Irradic Idle I own an 86 GT 5.0 HO, 5spd. The idle varies between 500-1100rpm--sometimes it holds relatively consistent, and other times it will surge between 700-1000rpm. Please Help

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11-09-2001, 11:03 PM	#2
Capri306 Moderator Join Date: Sep 1998 Location: Grand Rapids, Michigan, USA Posts: 1,001	Clean out the idle air bypass valve, the ports it attaches to, and the throttle body & throttle valve (butterfly) with some good quality throttle body & air intake cleaner (STP makes some good stuff). Don't use regular carb cleaner. You might find a toothbrush a big help, especially if this is the first time you've done it. After that, check TPS voltage. You should have a consistent voltage of about 0.80-0.95V, without any variation or wavering, between the center wire on the harness and ground. You have a speed density EFI system, so resetting the computer and idle speed shouldn't be necessary as on later MAF systems. When's the last time you did a complete tune-up? This includes plugs, cap, rotor, wires, and possibly coil (TFI coils are so cheap, I replace mine if there's any doubt). If you want to, you may wanna have the ignition module checked by an auto parts store, just to be sure. Check your ignition timing while you're at it, too. Okay, yeah, I'm a little obsessive about this, but I like my 'Stang to run well. ------------------ Capri306, Moderator, The Mustang Works Online *"PROUD TO BE AN AMERICAN!!!"*

11-10-2001, 07:14 AM	#3
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	After doing those very good suggestions, perform a self test in both KOEO and KOER modes and jot down any codes that come up. This will help isolate any equipment that is past it's prime and in need of replacement. Take care, -Chris ------------------ Retired Moderator MustangNet My site: Peckerwoods Pit Stop My teams site: Jim Porter Racing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN.

11-10-2001, 03:15 PM	#4
abesmith69 Registered Member Join Date: Nov 2001 Location: Ocala, FL, USA Posts: 62	all I did to fix my idle problem is disconnect the IAB for 5 minutes and then plug it back in, its worked fine! Thanks, Abe ------------------ 1990 Mustang GT Convertible, Blue with Grey ground effects and white top. Black Leather interior pw,pl,ps,pm, premium sound system. All stock =(

11-10-2001, 06:44 PM	#5
Comatose Registered Member Join Date: Oct 2001 Location: Goldendale, WA, USA Posts: 84	Thanks for the help....where is the IAB? I just bought this car two weeks ago and I'm not very experienced with EFI. The car had a complete tune-up before I bought it--new plugs, cap, rotor, wires, exhaust, etc,etc. abesmith69--Did you unplug it while it was running? Thanks