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RENIX buklhead connector and MAT sensor question.

xjtrailrider

NAXJA Forum User
NAXJA Member
Location
Roanoke VA
90' 4.0

What is the best way to disconnect and clean the bulkhead connector? Does it come apart from the inside or outside? This is the only connector I have yet to remove and clean. I do not have the FSM for my year model, only the RENIX FSM and its not covered there.

I run a air tube instead of the factory air box. Would I gain any performance by mounting the MAT sensor in the tube instead of the intake manifold. I feel it would give me a "true" air temp reading and not pick heat up from the manifold like the stock location does.

Also I need a good source for the MAT, no one locally can get one for me including the dealer. Most online sources are no longer in stock as well. I can use a CTS in the air tube since the MAT/CTS are essentialy the same sensor just the CTS is enclosed. I can't use the CTS in my manifold unless I drill and tap for the larger NPT size. The MAT is 1/4" NPT and the CTS is 3/8" NPT. I don't want to drill and tap the intake while its on the Jeep.

I plan on running the MAT sensor in both the air tube and in the manifold and put them on a switch so I can swap back and forth from winter to summer.
 
Try Partsamerica.com for Renix MAT sensor. Saw it listed there a few days ago.

As for bulkhead connector. You are thinking of the connector on the opposite side of the fuse box? I too would like to know that! :roflmao: Tried pulling on it the other day without any luck...

(The CTS will be slower to respond to changing temp. as the resistor is inside the brass. But I guess it will matter only when entering or leaving tunnels)
 
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xj88kjetil said:
Try Partsamerica.com for Renix MAT sensor. Saw it listed there a few days ago.

As for bulkhead connector. You are thinking of the connector on the opposite side of the fuse box? I too would like to know that! :roflmao: Tried pulling on it the other day without any luck...

I'll try Partsamerica, thanks!

Yes its the large connector beside the vacuum booster, I want to take it apart and clean it.
 
I found the info on the bukhead connector, I may just leave that alone, it appears that can turn into a disaster if the connector breaks in any way. I'm not having any issues at the momment, I'm just bored and needed something to fix!
 
The C101 connector is filled with sticky black sealant to prevent corrosion.
It just takes a little pulling and tugging to get it off once you have removed the center screw. I took mine off and cleaned it up, but eventually decided to cut it out entirely and splice all the wires together.
5-90 had a post sometime back about Chevy sensors which were mostly the same as the ones used on the Renix jeeps, mabye you can find one here:
http://www.injector.com/sensors.php?PHPSESSID=80f34b78e513026d0b0a8c2e731d4355
good luck........
 
tugalo said:
5-90 had a post sometime back about Chevy sensors which were mostly the same as the ones used on the Renix jeeps

I searched and couldn't find that post, I remember it though. I think I was in on the conversation.
 
Why bother? The ECM doesn't even look at the sensor once its warmed up and running in closed loop. You might see a slightly richer mix at wide open throttle.

From the 88 FSM:
Temperature Sensors
There are 2 temperature sensors used on this system.
Manifold Air Temperature (MAT) sensor, mounted in intake manifold,
measures temperature of incoming air/fuel mixture and Coolant
Temperature Sensor (CTS), located on left side of cylinder block just
below the exhaust manifold, measures temperature of engine coolant.
Information provided by these 2 sensors to ECU allows ECU to
demand slightly richer air/fuel mixtures and higher idle speeds
during cold engine operation.
 
lawsoncl said:
Why bother? The ECM doesn't even look at the sensor once its warmed up and running in closed loop. You might see a slightly richer mix at wide open throttle.

From the 88 FSM:
Temperature Sensors
There are 2 temperature sensors used on this system.
Manifold Air Temperature (MAT) sensor, mounted in intake manifold,
measures temperature of incoming air/fuel mixture and Coolant
Temperature Sensor (CTS), located on left side of cylinder block just
below the exhaust manifold, measures temperature of engine coolant.
Information provided by these 2 sensors to ECU allows ECU to
demand slightly richer air/fuel mixtures and higher idle speeds
during cold engine operation.

I tow with this Jeep, a richer mixture would help me at WOT. I'm going to play with it and see what happens. I plan on installing the MAT into the air tube and leave the one in the intke and put them on a switch and see how the power and economy compares.
 
As LawsonCL said, its not supposed to be in the loop once the jeep warms up,
however, I had a bad engine skip/miss/buck at 1800-2000 RPM hot or cold, and it went away when I replaced the MAT sensor. I also added HEAVY ground cables to the existing grounds so I'm not sure which action cured my problem.
anyway, follow the link I sent and the sensors are there for $16 and change.
 
tugalo said:
As LawsonCL said, its not supposed to be in the loop once the jeep warms up,
however, I had a bad engine skip/miss/buck at 1800-2000 RPM hot or cold, and it went away when I replaced the MAT sensor. I also added HEAVY ground cables to the existing grounds so I'm not sure which action cured my problem.
anyway, follow the link I sent and the sensors are there for $16 and change.

This link directs me to a temp sensor looking suspiciously like the HO sensor? (Which would be the same one available at most parts stores.) Does it have the same values as the Renix sensor? I ordered one like this from tellico 4x4 because their catalog said 88-??, and when I saw it had a different connection i measured resistance in it. I did NOT get the right values, but I'm not shure how far I can trust my multimeter... The only one I have found that looks like my original sensor is the (expensive) one at partsamerica...

looks like this: http://www.partsamerica.com/productdetail.aspx?MfrCode=SMP&MfrPartNumber=AX9&PartType=756&PTSet=A
 
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xj88kjetil said:
This link directs me to a temp sensor looking suspiciously like the HO sensor? (Which would be the same one available at most parts stores.) Does it have the same values as the Renix sensor? Is the connector the only difference? The only one I have found that looks like my original sensor is the (expensive) one at partsamerica...

looks like this: http://www.partsamerica.com/productdetail.aspx?MfrCode=SMP&MfrPartNumber=AX9&PartType=756&PTSet=A

They don't give the values of that sensor but if its 1000-50 Ohms range then it will work. That one has the correct Nycopac connector on it as well. Good find!
 
xjtrailrider said:
90' 4.0

What is the best way to disconnect and clean the bulkhead connector? Does it come apart from the inside or outside? This is the only connector I have yet to remove and clean. I do not have the FSM for my year model, only the RENIX FSM and its not covered there.

I run a air tube instead of the factory air box. Would I gain any performance by mounting the MAT sensor in the tube instead of the intake manifold. I feel it would give me a "true" air temp reading and not pick heat up from the manifold like the stock location does.

Also I need a good source for the MAT, no one locally can get one for me including the dealer. Most online sources are no longer in stock as well. I can use a CTS in the air tube since the MAT/CTS are essentialy the same sensor just the CTS is enclosed. I can't use the CTS in my manifold unless I drill and tap for the larger NPT size. The MAT is 1/4" NPT and the CTS is 3/8" NPT. I don't want to drill and tap the intake while its on the Jeep.

I plan on running the MAT sensor in both the air tube and in the manifold and put them on a switch so I can swap back and forth from winter to summer.
MAT, I got mine at Autozone over 2 years ago. You may have problems if you move it.

I am under the impression that the ECU still uses the MAT data even when it reaches closed loop operation, like at WOT when it reverts to open loop operation from CLO.
C-101 is held by a central screw, long screw and I think a few tabs. SCrew has to come out first, but "if ain't broke don't fix it".

MAT has the same resistance values as the CTS on the Renix. I think the values are posted in the RenX files thread, OEM forum. IIRC it goes from about 20,000 ohms to about 100 ohms, cold to hot, but I don't recall for sure.
 
Ecomike said:
MAT, I got mine at Autozone over 2 years ago. You may have problems if you move it.

I am under the impression that the ECU still uses the MAT data even when it reaches closed loop operation, like at WOT when it reverts to open loop operation from CLO.
C-101 is held by a central screw, long screw and I think a few tabs. SCrew has to come out first, but "if ain't broke don't fix it".

MAT has the same resistance values as the CTS on the Renix. I think the values are posted in the RenX files thread, OEM forum. IIRC it goes from about 20,000 ohms to about 100 ohms, cold to hot, but I don't recall for sure.

I chickened out and didn't move it! I was also thinking that RENIX kept reading the MAT after going into closed loop but didn't take time to look it up myself. I left the C-101 alone, i agree.

For some reason NO ONE locally can get the MAT sensor, I spent an hour at Advance Auto looking through old catalogues and searching on their system. This is the only sensor that is still original to my XJ, i would love to replace it as well.

My Jeep runs great, plenty of power, 17mpg mixed. Of course its as new as a 90' XJ can be unless it would have come from a time capsule.

Thanks for the help guys!
 
I believe it would be a good idea to move the sensor to the tube in front of the tps if you use a CTS as MAT-replacement. The CTS has the resistor capsuled in brass, and would read the manifold temperature rather than the air temperature if placed in the original position....
 
xjtrailrider said:
I chickened out and didn't move it! I was also thinking that RENIX kept reading the MAT after going into closed loop but didn't take time to look it up myself. I left the C-101 alone, i agree.

For some reason NO ONE locally can get the MAT sensor, I spent an hour at Advance Auto looking through old catalogues and searching on their system. This is the only sensor that is still original to my XJ, i would love to replace it as well.

My Jeep runs great, plenty of power, 17mpg mixed. Of course its as new as a 90' XJ can be unless it would have come from a time capsule.

Thanks for the help guys!

The local supply problem may actually be a what they call it problem. I think the parts houses call it IAT, or maybe IMT, Intake Air Temperature sensor. I forgot, but I had trouble getting it here too until I made them let me search their computer data base at Autozone.

If your deperate enough for an MAT I have one on my 87, I could swap XJ's with you, but mine only averages about 14.5 mpg so far, LOL!:laugh3:

Here is ohm dada at:
http://www.autozone.com/az/cds/en_us/0900823d/80/15/23/29/0900823d80152329/repairInfoPages.htm
"The MAT sensor reacts to the temperature of the air in the intake manifold and provides an input to the ECU to allow it to compensate for air density changes during high temperature operation."

Well I was partly right, Autozone calls it an AIR CHARGE Sensor in their parts database and MAT in their repair guide, such fun!

http://www.autozone.com/addVehicleI...nitialN,15900112/shopping/vehicleSelected.htm
 
xj88kjetil said:
I believe it would be a good idea to move the sensor to the tube in front of the tps if you use a CTS as MAT-replacement. The CTS has the resistor capsuled in brass, and would read the manifold temperature rather than the air temperature if placed in the original position....
But I suspect that Renix compensated for that in the calculation algorithyms. Also the manifold gets very hot, thus heasting the inbound air after it passes through the throttle body and past the TPS, which heats the incoming air to a temperature close to the manifold temperature.
Imagine the inbound air is at -20 F, engine is at 200 F, intake manifold at say 180 F, and final air temp entering the engine is 150 F, your method would result in a 20 + 150 = 170 F air temp error and thus result in an air density error calc in the computer that would cause errors in the O2 sensor computer confirmation calcs, causing the computer to ignor one of the sensors.
 
Ecomike said:
But I suspect that Renix compensated for that in the calculation algorithyms. Also the manifold gets very hot, thus heasting the inbound air after it passes through the throttle body and past the TPS, which heats the incoming air to a temperature close to the manifold temperature.
Imagine the inbound air is at -20 F, engine is at 200 F, intake manifold at say 180 F, and final air temp entering the engine is 150 F, your method would result in a 20 + 150 = 170 F air temp error and thus result in an air density error calc in the computer that would cause errors in the O2 sensor computer confirmation calcs, causing the computer to ignor one of the sensors.

Mike, how do you feel about using a MAT in the air tube and how will it help/hurt.
 
xjtrailrider said:
Mike, how do you feel about using a MAT in the air tube and how will it help/hurt.
LIke I already said below, behaps too technically, I think it wil cause serious miss fire problems leading the computer to ignor a sensor or 2 and then maybe switch to rich mode waisting gas.
 
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