MAT sensor replacement nightmare....

[mjeff87]

OK, got a new MAT sensor and decided to put it in this morning. 20 minute job, tops......not!

 

First off, the MAT on a 2.5 is alot harder to get to than on a 4.0 (it's tucked in right behind the TB and the valve cover, vaccuum tower thingy, and the manifold coolant line). Not easy to get a wrench on without removing all of the above, but I tried anyway and couldn't get any torque on it. So I cut the wires off it since it was coming out anyhow, and slipped a 3/4" spark plug socket over it on a long extension and proceeded to snap it off flush with the manifold :oops: Fished the guts out of it, went and bought a set of fluted extractors and spent an hour trying to get a socket to fit over the end of the extractor (3/8" square stock). That didn't work so I ended up using the ratchet end of a long 3/8" extension flipped over and slipped over the top of it, and a pipe wrench on the end of the extension. Borowed the wife's hairdryer :chillin: and let it run on high pointed on the manifold for about 10 minutes to try to warm it up some. About popped an eyeball, but it finally broke free and I was able to unscrew the rest of it

 

It was the factory sensor, and it had become one with the aluminum manifold over the years. Got the new one in, and it along with the new O2 sensor I put on last weekend have really brought the engine back to life.

 

It's not even noon, and I've already had 3 beers.....

 

Jeff

 

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[JeepcoMJ]

so, what does this sensor do?

[chicofuentes0224]

MANIFOLD AIR/FUEL TEMPERATURE Sensor

MAt sensor provides a signal to the ecu that changes depending upon temperature of the fuel/air mixture in the intake manifold. During high temperature conditions ECU will compensate for changes in density of air.

(TAKEN FROM 1988 FSM)

[mjeff87]

yeah, like chico says....

 

These 2.5's are only controlled by a couple sensors, O2, MAP, MAT, TPS, and coolant temp. They all work together to send data to the ECU, so it can control injector pulse length (which basically is the A/F ratio, since the single-injector on the TBI system sprays onto the throttle plate).

 

Jeff

[comancheman]

i don't have a wife but i do have a mom and sister. man do they get pi$$ed when they see their hair dryer hooked up to an extension cord in the drive way :D

[JeepcoMJ]

yeah, like chico says....

 

These 2.5's are only controlled by a couple sensors, O2, MAP, MAT, TPS, and coolant temp. They all work together to send data to the ECU, so it can control injector pulse length (which basically is the A/F ratio, since the single-injector on the TBI system sprays onto the throttle plate).

 

Jeff

 

:eek: :oops:

 

uh...my temp gauge isn't working. where is the ECU temp sensor?

 

 

my cherokee isn't running quite right, it's probably an easy fix (and I have at least one spare of every sensor I'm sure) so maybe that would help.

 

thanks

[chicofuentes0224]

Jeepco I'm not sure about the 2.5 but the 4.0 the coolant temp sensor to the ECU is located in the engine coolant jacket on the driver's side of the block, underneath the exhaust manifold

[chicofuentes0224]

Jeff, where did you get that MAT sensor? I can't find it at NAPA or Autozone. Neither one says they carry it.

[mjeff87]

I had to special order it from a local independant parts house I use down here. They called somewhere and told me they only had one in stock, so I grabbed it. I'll post up the manufacturer name and part number tonight when I get home.

 

Jeff

[mjeff87]

crap on crap....my wife thru out the box (I left it on the kitchen counter) :headpop: All I have is the receipt, and it's all abbreviated.....MFG name is "STR" and the part # listed is "*AX9". I'll run back up to the shop this week and have them look it up again, and get the full info on it.

 

Sorry!

 

Jeff

[chicofuentes0224]

Don't rush man, BLHTAZ said he might be able to get me one 2morrow. Thanks anyway for the help Jeff :cheers: