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Idle Air Control Valve question.

snowonweb

NAXJA Forum User
Location
Connecticut, USA
Hi.
So I am putting my XJ together after I did Head Gasket with new exhaust header, 99+ intake manifold and bored out TB (just bragging).
When I purchased my Intake, it came with TB and Idle Air Control Valve. So now I have 2 Idle Air Control Valves, original one from 92 is straight and the one from 99 has an elbow. So my first question is, does it make a difference? I looked up 92 XJ idle control valve and the picture shows replacement one with an elbow. Second question is that when I push that thing in, it doesn't come out and it takes some force to push it in. Does it mean that it's shot? Shouldn't it come out by itself?

Third issue is with the head. I remember when I took old head out I broke some kind of sensor on it but now I can't find it anywhere. What kind of sensor is in the head and where is it located?
I have read few threads about replacing that sensor onto the air filter intake tube, but I am so lost, it took me 1 hour to actually find out that the sensor on Throttle Body is called Idle Air Control Valve. I am new to mechanics and don't know any sensor names, but I am learning.

Please advice.

Thank You.

Jack

92 Jeep Cherokee Sport 4x4 4.0 L6 H.O. Automatic
 
A picture of the sensor or where it is mounted would help
 
well that's the problem I already mounted the new head and looked around everywhere and I can't find any sensors that go into the head. As far as Idle Air Control Valve, I'd like to know if there is a difference between 92 and 99 as 99 has 90 degree connector elbow while the OEM doesn't. Seems NAPA replacement has an elbow also although I never really seen it except the picture on Napaonline.com.
 
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Verify idle air control valve application is correct via a parts catalog like Rock Auto. That will tell you which is which and for what year.

If you have a 99 throttle body, I would imagine that you should be using a 99 idle air control.

Never force an idle air control pintle, as when you do that, it can create problems. Pintle must move freely.

If in doubt, get a new one.
 
The only sensor i can think of on the head itself is the water temp sensor on the back of the head. Or maybe the other water temp sensor on the thermostat housing. Neither could be adapted for air filter housing though.....

Well there is one in thermostat housing. I looked at it today, but I moved my hand across back of head and couldn't feel for any sensors. I think I am confusing myself, with whatever sensor it might be.
I am looking at this thread but the relocation sensor i was thinking about is the one in the intake manifold. Sorry for the confusion.
 
As far as Idle Air Control Valve, I'd like to know if there is a difference between 92 and 99 as 99 has 90 degree connector elbow while the OEM doesn't.

They will vary, depending on the year. My 98 has the IAC with no elbow, while my 96 has the elbow. You can see in the picture, that the connector from my 98 is physically too large to fit the 'elbow' IAC(96) in my hand.
P1010195.JPG
 
The 92 and 99 throttle bodies are different and use different components. You need to use the 92 throttle body and components. More specifically, your 92 wiring harness needs to use the 92 components, and those require the 92 throttle body.

The only sensor "in the head" that I know of is the sender for the temperature gauge. It's on the drivers side at the back left. The hole was deleted in 97 (you didn't say what year head)
 
The only sensor that would be relocated to the intake tube is the Intake Air Temperature sensor.
The reason why some owners relocate the sensor would be to fool the PCM to create a richer air/fuel mixture for idle. This trick is used on engines built for use with turbo and superchargers.

Hi.
So I am putting my XJ together after I did Head Gasket with new exhaust header, 99+ intake manifold and bored out TB (just bragging).
When I purchased my Intake, it came with TB and Idle Air Control Valve. So now I have 2 Idle Air Control Valves, original one from 92 is straight and the one from 99 has an elbow. So my first question is, does it make a difference? I looked up 92 XJ idle control valve and the picture shows replacement one with an elbow. Second question is that when I push that thing in, it doesn't come out and it takes some force to push it in. Does it mean that it's shot? Shouldn't it come out by itself?

Third issue is with the head. I remember when I took old head out I broke some kind of sensor on it but now I can't find it anywhere. What kind of sensor is in the head and where is it located?
I have read few threads about replacing that sensor onto the air filter intake tube, but I am so lost, it took me 1 hour to actually find out that the sensor on Throttle Body is called Idle Air Control Valve. I am new to mechanics and don't know any sensor names, but I am learning.

Please advice.

Thank You.

Jack

92 Jeep Cherokee Sport 4x4 4.0 L6 H.O. Automatic
 
well then huston we have a problem. My head has no sensors and I am not sure what year the head is. Throttle Body is 92 and stupid me didn't even check if the harness plug will fit the elbowed IACV. I actually ended up with two TBs and i am using the 92 TB.
I will double and triple check the head again but I am almost positive there are no sensors or holes with threads in them in my head. OOPS. I guess I ordered the wrong head.
 
I think you are referring to the MAT sensor.

This information is on the Renix series which preceded your ‘92XJ.

Look at your old intake manifold near the throttle body for a two wire sensor for your old MAT.



Manifold Air Temperature Sensor (MAT)

Information from http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

MAT is installed in the top of the intake manifold. Testing is the same as the CTS. Make sure engine is WARM.

What does it do? Pretty much the same thing as the CTS, but based off incoming temperature.

Update: Basically - this sensor functions by providing a resistance-to-ground circuit that the computer (ECU) uses to determine how much fuel the engine requires. (The hotter the air in the intake manifold - the lower the resistance.) The resistance of this sensor is read by the ECU which in turn adjusts the air/fuel ratio as close to 14.7:1 as possible. When a manifold air temperature sensor fails (open circuit / no continuity) the high / infinite resistance will cause the ECU to enrich the fuel mixture because it thinks the temp is really cold when it really isn't. A short to ground would cause a 'no-resistance' fault causing the ECU to think the air temperature was extremely hot and lean out the fuel mix.
 
It's not a big deal to route the gauge sender somewhere else. Most of us just drill and tap the flat spot in the front of the thermostat housing then extend the sender wire up there. The sender uses a 1/8 NPT tapered plumbing thread. Any home improvement center and most hardware stores will have the tap in the plumbing aisle. It's tapered so only go far enough to make a full thread and don't bottom the tap or you'll never get a seal.
 
There is a sensor/sender on the thermostat housing. My understanding is that 91-97 had two. one on top of head and one in thermostat housing.
Can I just splice the wires and connected my gauge to the sender/sensor in the thermostat housing.
I really would hate to take the head off again.
 
No the one that is already there is for the computer to use so it knows when the engine has warmed up and when it gets too hot. That sensor uses a different resistance scale than the one for the gauge.

Why do you think you need to remove the head again?
 
Because my remanufactured head doesn't have the Coolant Temp Sensor Location like my old head did. So how do I drill the hole for the temp sensor without removing the head, Unless I can put that sensor somewhere else, perhaps in the rubber hose?
 
It's not a big deal to route the gauge sender somewhere else. Most of us just drill and tap the flat spot in the front of the thermostat housing then extend the sender wire up there. The sender uses a 1/8 NPT tapered plumbing thread. Any home improvement center and most hardware stores will have the tap in the plumbing aisle. It's tapered so only go far enough to make a full thread and don't bottom the tap or you'll never get a seal.

Unless I can put that sensor somewhere else, perhaps in the rubber hose?

rubber hose won't work-- coolant sending unit needs to ground to function.

I think EHALL has the right answer for ya^^
 
photo066s.jpg


A little dirty but thats the thermostat housing with sensor already on the right side. Good thing someone posted a picture on where i should tap it, otherwise I was lost as I don't see any flat spots except the round thing.
So I should tap into that little round spot.
Thank You very much.
 
Does anyone have the part number for that particular coolant temp sensor. I had purchased one sensor, Duralast SU326 but I have a feeling it's the other sensor and autozone shows only one sensor.

Update. I looked at Napaonline and I see now the second sensor called temp sender switch gauge.
 
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