Replace IAC
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Yes, the IAC is on the side of the throttle body , not on the plenum...The throttle body needs to be removed to get to the IAC (4 bolts)..Did you check the one you have to see if it's bad??? Sometimes all they need is to be removed and cleaned, also the plate on the bottom of the TB should be removed and the air passages cleaned.....WW
Last edited by WW7; May 19, 2014 at 02:01 PM.
Thread Starter
Instructor
Joined: Apr 2014
Posts: 230
Likes: 7
From: NJ
I am confused, I thought the iac was on the bottom side of the plenum back near the distributor? Does my 91 have an iac or is it called mat? Can some one please point me to some pictures since I am not able to find any?
your help is greatly appreciated!
your help is greatly appreciated!
Thread Starter
Instructor
Joined: Apr 2014
Posts: 230
Likes: 7
From: NJ
just fond this on this here on this forum:
The IAT sensor toward the rear of the plenum (near the distributor) on the bottom side. If you stand on the driver's side and look on the bottom of the plenum between the 2 runner pairs, that is it. If you are just checking the sensor, it has a detachable pigtail... when you find the sensor, just trace the wires back and there should be a harness right near the distributor that you can unplug to do a check with a meter. Just be careful with the "car" end, as it can get lost back there.
You *might* be able to change the sensor from between the runners, but most likely you would need to pull the plenum.
The IAT sensor toward the rear of the plenum (near the distributor) on the bottom side. If you stand on the driver's side and look on the bottom of the plenum between the 2 runner pairs, that is it. If you are just checking the sensor, it has a detachable pigtail... when you find the sensor, just trace the wires back and there should be a harness right near the distributor that you can unplug to do a check with a meter. Just be careful with the "car" end, as it can get lost back there.
You *might* be able to change the sensor from between the runners, but most likely you would need to pull the plenum.
Le Mans Master
Joined: Mar 2004
Posts: 5,107
Likes: 171
From: Dublin CA
The sensor your talking about under the plenum is a SENSOR. You will more than likely have to take the plenum off to get to it. Think this is a single or two wire plug that plugs into this one.
The IAC is under the throttle body and controls the amount of air going into the TB at idle. There is a four wire plug that plugs into this on the passenger's side of the engine/TB.
The IAC is under the throttle body and controls the amount of air going into the TB at idle. There is a four wire plug that plugs into this on the passenger's side of the engine/TB.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The IAT (Intake Air Temperature) sensor and the MAT (Manifold Air Temperature) sensor are different names for the same sensor. It's located on the bottom of the plenum at the rear. I don't think it's possible to get a wrench on it without removing the plenum (the runners and other stuff are in the way):
I don't know what your reason is to want to access this sensor, but on my car the ONLY thing it does is enable EGR. For those people who think they should relocate it in front of the throttle body, don't bother. It's a waste of time and money and does NOTHING for performance.
I don't know what your reason is to want to access this sensor, but on my car the ONLY thing it does is enable EGR. For those people who think they should relocate it in front of the throttle body, don't bother. It's a waste of time and money and does NOTHING for performance.
Last edited by Cliff Harris; May 20, 2014 at 02:29 AM.
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Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
It is very easy if you have a Torx T-40 bit to get the bolts out. You can remove the 10mm bolts holding the throttle body to the plenum and just let the throttle body hang there. It will be supported by the various hoses that attach to it.
The brackets that hold the throttle and cruise control (and TV cable on automatics) cables are all 10mm bolts.
The flare nut that holds the brake vacuum booster line is pretty big (I don't remember the size -- 5/8"?), but non-critical so you can use anything that will get it off.
The plenum can be stuck in place, so you might have to use a little force. It's sort of wedged in between the runners (I think the mating surfaces are angled very slightly). I generally smack it in the front with a 2 lb rubber mallet to break it loose.
I have re-used the plenum gaskets. They only seal air, so they are not super critical. You don't want a vacuum leak, so use your own judgment.
The brackets that hold the throttle and cruise control (and TV cable on automatics) cables are all 10mm bolts.
The flare nut that holds the brake vacuum booster line is pretty big (I don't remember the size -- 5/8"?), but non-critical so you can use anything that will get it off.
The plenum can be stuck in place, so you might have to use a little force. It's sort of wedged in between the runners (I think the mating surfaces are angled very slightly). I generally smack it in the front with a 2 lb rubber mallet to break it loose.
I have re-used the plenum gaskets. They only seal air, so they are not super critical. You don't want a vacuum leak, so use your own judgment.