How do you tell if the IAB is bad?

Scappoose · 07-01-2002, 12:11 PM

I had the high idle, cleaned out the IAB about 6 months ago and things were cool until last week. The idle started sticking again so I pulled it off to clean and it wasn't too dirty. Cleaned it and the idle was good for about four days. Is there something else that would cause this or does the fact it keeps sticking mean it's bad? Any help would be appreciated. Thanks.

explicitone · 07-01-2002, 03:39 PM

is your throttle sticking?
try and clean the throttle linkage on the cable and the t.b

Scappoose · 07-01-2002, 03:44 PM

Nope, the throttle and linkage are good (Had that problem a couple of months ago).
Also, this only happens after I've been driving the car 20 or 30 minutes. Idle is fine at start. If I shut it off then restart, the idle is fine for a couple of minutes.

90LXhatchback · 07-01-2002, 05:06 PM

TPS sensor maybe check the setting or maybe its a bad one

PKRWUD · 07-01-2002, 07:00 PM

When you are experiencing the problem, unplug the IAC (IAB) and see if the problem goes away.

Take care,
-Chris

65efi · 07-01-2002, 09:47 PM

When you say the idle is sticking, is it idling high or low?....

If it dies or idles low, it could be the solinoid is not opening up far enough. Disconnecting the solinoid while it's idling should kill the motor or at least drop the idle WAY down. This is the most simple test to see if it's working.

Have you checked for codes?

Scappoose · 07-02-2002, 11:04 AM

It sticks high. Did it this morning, unplugged the connector (I hate when I overlook the obvious) and the idle dropped to normal. Is it safe then to assume the IAB/IAC (which is it, anyway? I've seen both references) is bad?
Thanks.

PKRWUD · 07-02-2002, 02:18 PM

You can try cleaning it out with CRC Brakleen (green can), but it should probably just be replaced. I don't know when the designation changed, but today it is commonly known as the Idle Air Control valve (IAC). Some people will still refer to it as the Idle Air Bypass valve (IAB), so it is good to be familiar with both terms.

Take care,
-Chris

07-01-2002, 12:11 PM	#1
Scappoose Registered Member Join Date: Nov 2001 Location: Scappoose, OR Posts: 42	How do you tell if the IAB is bad? I had the high idle, cleaned out the IAB about 6 months ago and things were cool until last week. The idle started sticking again so I pulled it off to clean and it wasn't too dirty. Cleaned it and the idle was good for about four days. Is there something else that would cause this or does the fact it keeps sticking mean it's bad? Any help would be appreciated. Thanks. __________________ 91 GT - White, MAC cold air induction (that's it so far) 69 GT - Winter Blue, 351, C-4, mild mods 69 Mach I - Acapulco Blue, 351, T-10, bone stock

07-01-2002, 03:39 PM	#2
explicitone Registered Member Join Date: Apr 2002 Location: racine ,wi Posts: 691	is your throttle sticking? try and clean the throttle linkage on the cable and the t.b __________________ RUN IT STAIGHT AND RUN IT HARD ________ Novi 2000 60' 1.46 1/4 10.67 mph 126.5 _________

07-01-2002, 03:44 PM	#3
Scappoose Registered Member Join Date: Nov 2001 Location: Scappoose, OR Posts: 42	Nope, the throttle and linkage are good (Had that problem a couple of months ago). Also, this only happens after I've been driving the car 20 or 30 minutes. Idle is fine at start. If I shut it off then restart, the idle is fine for a couple of minutes. __________________ 91 GT - White, MAC cold air induction (that's it so far) 69 GT - Winter Blue, 351, C-4, mild mods 69 Mach I - Acapulco Blue, 351, T-10, bone stock

07-01-2002, 05:06 PM	#4
90LXhatchback Registered Member Join Date: Apr 2000 Location: Ft Lauderdale FL, 33026 Posts: 86	TPS sensor maybe check the setting or maybe its a bad one __________________ "old car" GONE!!! 3:55,2 chamber flows, cobra clutch, pro chamber, k&n filter,Tri Ax shifter, 75mm mass air, Holley FPR,Mac pulleys "New car" 87 coupe.....as of 12/21/02 shorty headers,h-pipe,dumps,edlebrock intake,sub-frames,3:73's,lowered

07-01-2002, 07:00 PM	#5
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	When you are experiencing the problem, unplug the IAC (IAB) and see if the problem goes away. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

07-01-2002, 09:47 PM	#6
65efi Registered Member Join Date: May 2002 Location: Portland, OR Posts: 37	When you say the idle is sticking, is it idling high or low?.... If it dies or idles low, it could be the solinoid is not opening up far enough. Disconnecting the solinoid while it's idling should kill the motor or at least drop the idle WAY down. This is the most simple test to see if it's working. Have you checked for codes?

07-02-2002, 11:04 AM	#7
Scappoose Registered Member Join Date: Nov 2001 Location: Scappoose, OR Posts: 42	It sticks high. Did it this morning, unplugged the connector (I hate when I overlook the obvious) and the idle dropped to normal. Is it safe then to assume the IAB/IAC (which is it, anyway? I've seen both references) is bad? Thanks. __________________ 91 GT - White, MAC cold air induction (that's it so far) 69 GT - Winter Blue, 351, C-4, mild mods 69 Mach I - Acapulco Blue, 351, T-10, bone stock

07-02-2002, 02:18 PM	#8
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	You can try cleaning it out with CRC Brakleen (green can), but it should probably just be replaced. I don't know when the designation changed, but today it is commonly known as the Idle Air Control valve (IAC). Some people will still refer to it as the Idle Air Bypass valve (IAB), so it is good to be familiar with both terms. Take care, -Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!