Symptoms of a bad IAC valve?

roger · 04-27-2009, 09:21 AM

Hi everyone:

Need the group's collective knowledge here. I have a '98 Tacoma 4x4, V6. I am wondering what the typical symptoms of a bad IAC valve are? Sometimes (more often in the last week or so) the truck will idle around 2,000 rpm on a cold start; after a while it will go back to a normal idle.

Reason I suspect the IAC is, a while back I had a CEL on and the computer was throwing a code for a bad IAC. My mechanic cleaned out the throttle body and the code went away. Now it is not throwing a code but the idle-up is screwy. Want to be sure it is the IAC before spending $$ on the part...

Thanks!

This ad is not displayed to registered members.
Register your free account today and become a member on Yotatech!

cadman · 04-27-2009, 11:07 AM

I had a bad IAC valve and the only symptom was the high idle, 1700 rpm cold and 1200 rpm hot, no CEL. I replaced the valve and idle has been normal since.

stir_fry_boy · 04-27-2009, 12:00 PM

I have actually cleaned mine up really good, actually taking it off the throttle body which can prove sometimes difficult. You have to take off the valve anyway to replace it but you can really clean it out where is adjusts in the throttle body with some carb and choke. In my V6 camry, it would start and then quit. Bad IAC. I took the throttle body completely apart, including the IAC valve and found that it wasn't even moving at all. Cleaned everything really, really good, put a little oil around the rubber gaskets to seal them and it works awesome, no more trouble. I probably used about 2 cans of Carb and choke.
BTW, if you just spray carb and choke into the throttle body with it on the car and running, it will not clean the IAC.

roger · 04-27-2009, 01:46 PM

Alright...I'm reasonably sure that is the issue. I'm going to just replace the IAC since the mechanic already reamed it out once; chances are if I just spray carb cleaner on it I'll be in the same boat in a few months. Thanks!

okie81 · 09-14-2009, 05:03 PM

When I had my A/C on, the idle would intermittiently drop down to 300-400 rpm's along with a "click" sound. I cleaned the IAC = smooth idle and no more rpm drop w/ the Air Conditioner on.

04-27-2009, 11:07 AM	#2 (permalink)
cadman Registered User Personal Sales Rating: (0) Join Date: Jan 2005 Location: Orange County, SoCal Posts: 553	I had a bad IAC valve and the only symptom was the high idle, 1700 rpm cold and 1200 rpm hot, no CEL. I replaced the valve and idle has been normal since. __________________ "If it's worth doing, it's worth doing right" my father-in-law 2011 Tacoma 4WD TRD OR DCSB, TRD SC, Tow Pkg Custom 4X Innovations bolt-on sliders 1989 4wd Xtra Cab, 3.4L swap SOLD

04-27-2009, 12:00 PM	#3 (permalink)
stir_fry_boy Registered User Personal Sales Rating: (0) Join Date: Mar 2009 Location: SLC, UT Posts: 371	I have actually cleaned mine up really good, actually taking it off the throttle body which can prove sometimes difficult. You have to take off the valve anyway to replace it but you can really clean it out where is adjusts in the throttle body with some carb and choke. In my V6 camry, it would start and then quit. Bad IAC. I took the throttle body completely apart, including the IAC valve and found that it wasn't even moving at all. Cleaned everything really, really good, put a little oil around the rubber gaskets to seal them and it works awesome, no more trouble. I probably used about 2 cans of Carb and choke. BTW, if you just spray carb and choke into the throttle body with it on the car and running, it will not clean the IAC. __________________ 2002 T4R 4WD Onyx Black Sport with leather. Last edited by stir_fry_boy; 04-27-2009 at 12:01 PM.

04-27-2009, 01:46 PM	#4 (permalink)
roger Registered User Personal Sales Rating: (0) [OP] Join Date: Jun 2004 Location: Austin, TX Posts: 480	Alright...I'm reasonably sure that is the issue. I'm going to just replace the IAC since the mechanic already reamed it out once; chances are if I just spray carb cleaner on it I'll be in the same boat in a few months. Thanks! __________________ Looks like I picked the wrong week to stop sniffing glue.

09-14-2009, 05:03 PM	#5 (permalink)
okie81 Registered User Personal Sales Rating: (0) Join Date: Aug 2008 Location: Nor, CAL Posts: 1,808	When I had my A/C on, the idle would intermittiently drop down to 300-400 rpm's along with a "click" sound. I cleaned the IAC = smooth idle and no more rpm drop w/ the Air Conditioner on. __________________ 2001 Toyota 4Runner SR5 4WD TRD supercharger, Toytec Coilovers, OME 890's, 285 Duratracs, baseball card in spokes

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
where is the IAC valve???	89pickupsr5	86-95 Trucks & 4Runners	10	03-21-2012 05:53 AM
IAC Valve Cleaning	Quattro15	95.5-2004 Tacomas & 96-2002 4Runners	9	09-14-2009 04:08 PM
2.7L IAC valve question	Uncle Meat	95.5-2004 Tacomas & 96-2002 4Runners	0	07-24-2008 06:14 PM
Cleaning your IAC valve	kevin444	95.5-2004 Tacomas & 96-2002 4Runners	0	07-22-2007 09:30 PM
IAC valve?	Gabe	95.5-2004 Tacomas & 96-2002 4Runners	3	03-06-2005 04:05 PM

09-14-2009, 05:03 PM
Yotatech 4WD Truck Paid Advertisement