Possible faulty temp sensor?

[Z.m4v]

Hi all. I have a 1996 jeep xj country 2wd with a transmission out out of a 2000.
My issue is that when I first start the jeep. It seems to run very rich (rough idle, strong fuel smell) until it is fully warmed up. The temp gauge itself reads fine but I'm wondering if the sensor itself could be sending a bad signal to ecu. Or if thermostat could be stuck? Anyways it is also getting seriously bad mpg, like 150 miles on a full tank. Any insight is appreciated.

 

[Z.m4v]

Both 02 sensors have been replaced, I read that the gauge on 96+ is controlled by the pcm which means there is only the sensor on the thermostat? Is that correct, If so would I need a sensor, sender, or combination

 

[Tim_MN]

Are the symptoms from before, or the result of some recent maintenance, modifications, or other changes? Have you looked for a fuel leak, where is the gas smell originating from? Are the injectors dribbling fuel during operation or after shut-down?

A drop in the mpg's 30-40% often signals faulty O2 sensors, have you tested the O2 sensors. Have you inspected/tested the O2 sensor fuses? Is there an exhaust leak?

Did you install NTK O2 sensors and NOT Bosch or auto parts store brand Chinese junk?

The temperature sensor can be tested for proper function, as can most of the OBD engine sensors. New thermostats are inexpensive, but don't buy a cheap one.

 

[Z.m4v]

Are the symptoms from before, or the result of some recent maintenance, modifications, or other changes? Have you looked for a fuel leak, where is the gas smell originating from? Are the injectors dribbling fuel during operation or after shut-down?

A drop in the mpg's 30-40% often signals faulty O2 sensors, have you tested the O2 sensors. Have you inspected/tested the O2 sensor fuses? Is there an exhaust leak?

Did you install NTK O2 sensors and NOT Bosch or auto parts store brand Chinese junk?

The temperature sensor can be tested for proper function, as can most of the OBD engine sensors. New thermostats are inexpensive, but don't buy a cheap one.

The jeep was sitting for about a year with a broken trans, I replaced it at home with an aw4 out of a 2000 2wd. Converted output speed sensor to thr 1996 style and used the tail shaft from the 96 trans so all wiring is untouched. After that I replaced both 02 sensors as well as the tps. I just looked at my order history and it looks like I definitely cheaped out on the 02 sensors. for whatever reason I bought from 2 different brands, (walker and denso yikes) doesn't make sense to me now but I think I was just eager to get it driving again. But, it did drive very good and the problem went away completely, however I have 2 other vehicles that I'm working on so jeep sat for about 2 months. After driving it again the problem has started to occur but not to the same severity

When I start the jeep it idles very rich, almost sounds cammed very close to stalling, most times if I Try and drive right after starting/ putting into reverse or giving slight gas is enough to cause it to stall out. Once its started warming up more i can drive but it hesitates around 2500 rpm. Once it is up to 200-210 it drives flawlessly and no problems.

Gas smell is typical rich fuel mixture from the exhaust goes away after engine fully warmed, then it just smells like old jeep

Seems like mixing cheap Chinese 02s probably wasn't the best idea? I know I'd the heating element is bad it throws everything off. Will replace those with ntk, also how to test coolant temp sensor to be sure?

 

[Unclewolverine]

My 96 has the gauge sensor on the back of the head, the computer sensor on the thermo housing.

 

[Z.m4v]

Damn transition year lol, so that means if the 02 sensors aren't the problem it could be the sensor sending a bad reading to ecu but the gauge sensor showing correctly?

 

[clean96XJ]

Make sure radiator system is full fluid. Burp it. No air bubbles.

IF my memory is correct.. the temp sensor to PCM is on front thermostat housing.
Temp sensor on back of engine is for the gauges. (Just did this test last month.)

Test temp sensor to PCM:

Does the electric fan turn on (past 210 F)?
hint. Throw a tarp on front of jeep.. she'll warm up real fast.

 

[Z.m4v]

Hey so I'm wondering if it's actually my fuel gauge reading lower than reality?
The other day I filled up from the needle on E, took 14 gallons to fill. Today the needle is reading half full and only needed 6 gallons. Being a 20 gal tank it seems like it's reading 4-6 gallons lower??

 

[Z.m4v]

Make sure radiator system is full fluid. Burp it. No air bubbles.

IF my memory is correct.. the temp sensor to PCM is on front thermostat housing.
Temp sensor on back of engine is for the gauges. (Just did this test last month.)

Test temp sensor to PCM:

Does the electric fan turn on (past 210 F)?
hint. Throw a tarp on front of jeep.. she'll warm up real fast.

Electric fan comes on after 210, means sensor is good?

 

[Unclewolverine]

Electric fan comes on after 210, means sensor is good?

My e fan doesn't come until halfway between 210 and the red zone, I want to say it's like 226 before it's supposed to come on.

Fill it up and reset the trip, drive, fill up again, divide the fuel used by the miles driven. Easy solution to see what your gas mileage actually is.

 

[clean96XJ]

Yes @210 ish sensor is good.


According to the internet, 1996 jeep cherokee temperature sensor should turn electric fan on at ~217 F.

Electric Radiator Fan...Help?

www.cherokeetalk.com

bought a new temp sensor (by mistake and installed cause newer is better).. never triggered the e-fan
reinstalled original. according to jeeps gauge, sensor triggered ~ 210 F
So, if you buy a new one check before you cant return it.

my MPG 4.0 + 235mm tires + 5 speed
mixed driving (biased to non highway) ~= 17.5 mpg

Normal Engine temp per gauge is 200 F using 195 F thermostat
Original fan clutch 135k mileage