Do you still have the original sensor? Perhaps just put that in the new pipe if the old sensor is still good.

 

Thought about that but my local Radio Shack beat Radio Shack Corporate out of business. Found a 100 ohm and 2-320 ohm in the junk box. In parallel that is about twice what I need.

Next town, 20 miles away, has an open RS and a Chinese Buffet . . . and the best pawn shop/gun/reloading store in the area . . . and the wife is quilting with friends in the opposite direction. A day off . . . .

Great thought, wish I did. The plastic cross over pipe was so rotten I tossed it. But it may have read much the same as the new Denso one as I had never measured coolant temp with the IR meter and the Jaguar StupidGuage would not have displayed anything out of sorts.

But the difference has always been since November that the fans run all the time after the car has warmed up with the AC off.

Perhaps Coventry West will provide advice.

 

Hmmm...out of character for tight -wad Tom

I have a used one is you want it (free). It is from my 2003 S-type when I changed the front pipe assy. It has same Denso part number BTW.

 

I would appreciate the sensor. Maybe 10% variation is within Denso's engineering specs. Or, at least I could document the affects of aftermarket sensors.

I am surprised that you have not run into high temp readings with the RealGauge.

Is there an adjustment on the circuit board to 'tune' the RealGauge?

Just went through my junk box and have things that I had forgotten including a Ford temp sensor but no Jaguar one. Did find a full set of Jaguar valve cover gaskets that I had forgotten about.

 

Yes, you can set RealGauge to display as you wish through a software calibration procedure I had created for '96-'99 models which have wider tolerances in the instrument cluster assembly http://www.thejagwrangler.com/upload...ration_2.3.pdf . However, that will just mask the issue, since as you know it is definitely not normal for your fans to be running when cruising at modest speeds.

If RealGauge and OBDII are reading the same, they are reading exactly what the temperature sensor sees (unless the ECU has a fault).

I'll send you the sensor. We'll see if that sheds light or adds to the mystery.

 

That has always been my problem since I replaced the rotten plastic cross over pipe with the one from Coventry West.

 

Rainy, foggy morning so here are the measurements. While I attempted to raise the temp slowly I would attribute the differences between the published measured resistance and my measurements more to a difference in reaction time between the thermistor and the thermometer and/or similar lack of precision on the published reference. As a calibration for my DVOM I found three of Radio Shack's finest 330 ohm 5% resisters in my junk drawer and they measure 327/328 ohms on two different meters.
. . . . . . Ohms
*C Pub Meas Delta
Boil . . . . 187 TB
92 . . . . .220
90 249 220 29 250
88 263 231 32
86 274 245 29
84 292 263 29
82 309 285 24
80 322 298 24 320
78 342 318 24
76 361 330 31
74 383 358 25
72 407 376 31
70 432 402 30 400
68 460 431 29
66 487 460 27
64 520 490 30
62 555 521 34
60 591 556 35
58 633 596 37
56 681 638 43
54 730 668 62
52 776 720 56
50 833 780 53
48 895 821 74

Generally, it is linear from 60*C/140*F which I would interpret as the thermistor is functioning as designed only reading 30 ohms too low.

 

Not so much do I want the sensor but would appreciate it if you would measure the resistance at 70, 80, 90*C.

Bryan is sending me another brand of the same sensor to see if that makes any difference.

 

The sensor is already in the mail....

 

Got the sensors from both WhiteXKR and Bryan at Coventry West today and got the DVOM and cooking temp thermostat out.

Steve's OEM used 'S Type' sensor measured 413 ohms at 70*C, 311 ohms at 80*C and 233 ohms at 90*C. Jaguar's specs say 435, 320 and 250 ohms.

Remember, thirty ohms translates to 10*C to the ECM and the decision to operate the fans but the varistors are not exactly linear.

Coventry West's Uro brand sensor was closest at 419, 315 and 246.

Installed the Uro sensor but am seeing operating temperature still in the high 90's on the TORQUE app.

New thermostat next as it is easy. Water pump in hand for the next step.

Remember . . . none of this would be visible with the Jaguar temp gauge. You could drive out of a dealer with the engine running at 100*C and no one would know.

Another reason to explore the RealGauge.

 

High 90s may be right?

The goal is to run hot to improve mpg & emissions. Just not too hot...

 

The engineered normal temperature has never been determined. With an 84*C thermostat my thought is that that should sorta determine normal.

I just went through all this with my V8 Volvo. It has an 80*C thermostat and stays there or might move up to 84* when the fans come on. Then it cools down to the 80* point and the fans go off.

Today's entertainment has been to evaluate the Jaguar temperature regulation and fan operation with the new sensor installed.

With 18*C/64*F ambient temp the fans come on at 96*C as measured on the OBDII driven TORQUE app. Using the IR thermometer the head temperature is 91*C and the brass body of the sensor measures 74*C. The fans go off at 91*C on the TORQUE reading. The RealGauge reading is correspondingly above the 85* point as identified by the installation instructions.

Since the latest sensor is still a few ohms below the resistance values in the Jaguar table that might account for the differences between the thermostat specs and the measured head temperature. Remember, 30 ohms is 10*C in this section of the varistor's resistance slope.

Also remember that anyone with only the Jaguar idiot temperature gauge would be blissfully unaware of any of this except maybe for the fans running too much.

At least the fans do not run all the time now. In fact I had to run the engine rpm up to get the fan to come on as they never did at idle.

I guess I have to declare the fan problem solved although the measuring tools do not accurately reflect the correct information.

Thanks to Steve at JagRangler and Bryan at Coventry West for helping and putting up with me.

 

See page 11.4 of http://www.jagrepair.com/images/Trai...ual-9-5-01.pdf for the rated fan switching points.

In my experience, on my XKR, the switching points are 5-7 degrees F higher. It could be a programmed difference on the XKR or just system tolerances.

 

WOW!

That is one info filled document. That needs to be stored in the forum's info base.

Love to take that course.

It also confirms that the fans should come on at 90*C. Mine now comes on at 91*C as measure with an IR temp gauge on the head. Never mind that the sensor/gauge is screwy.

 

It IS in the forum (well site) info base (er, I think - anyway it's useful to crawl around Gus's site whether or not).

If the coolant doesn't heat enough, the newer PCM's throw codes. Don't know if yours will or not.

 

y does my engine coolant light keep coming on I replaced my thermostat an housing fan dnt come its normal water just comes out temp hand dnt move its normal wat else can it be

 

I would love to help but I cannot comprehend what you are trying to type on your phone while driving.

 

my fan work but evey thing is normal water just bubbles out if I runn it an I have to stop 5 or 6 times an keep putting water in it an if I run it fast it come on wat da problem

 

ditto.

 

ok I replaced my thermostat an housing on my jajuar xj8 but it still says engine coolant low my temp hand is normal only thing is I have to keep putting water in it 5 or 6 time wat else do I gotta do to resolve da problem