Thanks for this help lads.

You know what?
Screw it, I am going to buy a smoker to test the integrity of the system. A valuable tool I should already own. Then I will know for sure what my issues are with air / vacuum leaks

Bernie

 

Don:
I take issue with changing parts preemptively on a 20 year old car! Or any other age car for that matter (not that I have not done it).

The water temperature sensor can be read with an OBD scanner which should be a primary tool for maintaining a car's engine, The symptoms were not reported to be temperature or run-time dependent. The measurements seem normal. Save the money towards some diagnostic tools.

I say look for the vacuum leak via the propane gas method, the carbcleaner spray method, the tube in your ear method, or a smoke machine. Do not throw parts at it.

 

re smoke machines
I bought mine in a moment of no spare time, but you can make one for $15.00 and an hour or two using a paint can, an electric soldering iron, and some form of low air pressure (which you need for most smoke machines anyway).

 

https://www.jaguarforums.com/forum/x...econds-132409/

Others reported the MAF as the culprit. Read through the thread and see if anything there sounds interesting.

Please let us know how it turns out!

 

Ross,

As a general rule I agree completely. But since a new ECTS can be had for less than USD $8.00, and it's such a critical EMS component, to me it makes sense to replace it on a 20-year-old car to rule out any dynamic issues the original sensor may have developed that could be contributing to improper fueling. Not only is it cheap, it's very easy to replace, so like the CKPS, I personally recommend that it be replaced before it fails.

After re-reading all of Bernie's measurements, it appears that his ECTS is probably not too far out of range, assuming it is swinging smoothly with changes in coolant temps. Some of the measurements he reported were questionable, but when taken as a whole, I would agree that the ECTS is less likely his problem than an air leak.

Cheers,

Don

 

Vee,

It looks like you have danced around with this issue for a long time!
Going to refer to it as I nail down what my problem actually is. Sounds like it is going to be a leak somewhere........

First step for me is to build or buy a smoker. Like I said, I should have one anyway because I work on a few older cars. That should reveal quite a bit of info I think.

Your many posts have probably saved me quite a few dollars as far as things it probably isn't so thanks for that.

Someone should sticky the 32 Second Dip as an ongoing Jag issue.

 

Was just thinking.

I work in the entertainment industry where access to smoke machines is routine. The only issues I can see with using one of those is first the attachments for a hose as the tip on a smoke machine gets hot and secondly, regulating the pressure which I think should be easy.

Has anyone ever tried one?
Water based vapor which shouldn't harm anything in the system.

Bernie

 

I would not go with water vapor. The crankcase is part of the intake system and sending water down there does not seem like a good idea! Also, I am not sure if the water would not condense before seeping out of the leak.

 

Its not water per se, just a water based fluid.
I would suggest that with so little being induced into the system, it would be burned up in milliseconds when the car is started.

But I will look around for alternatives.
There is a guy on ebay selling homemade versions for under 100.00 so it might make sense to just run with that

B

 

Bernie- just google 'Homemade automotive smoke machine' and you'll find many examples. And like Ross said, forget the the water vapor.

 

Hey Lads,

So interesting update.

Yesterday I got some time to do some testing. I have also been getting high temp readings on my aftermarket temp gauge I installed so I figured that while I test the CTS I would also use it as an opportunity to check my engine temp readings.

So the car was cold and I disconnected the 2-way connector on the CTS and hooked up my meter to it set to ohms. I downloaded a chart from Jag Lovers to compare engine temps to measured impedance and fired the car up. I have since replaced the thermostat in the engine as well.

So I let the car soak for close to an hour in the driveway. Initially I didn't have the fans running but as the temps started going up, I turned them on.

So I was now comparing the impedance on the CTS to the temp gauge in the car. The impedance continued to drop to around 250 ohms and then would move around in that area. As low as 247 but no lower than that. The chart indicated that this should represent about 194F and my infrared thermometer was in agreement that the engine was at about 192F (so give or take a few degrees on the measurement). When I checked the gauge in the car it was showing over 220F! So my question is how accurate are these impedance measurements to actual engine temps?

This has been a real mystery to me because the reason I put the aftermarket gauge in in the first place was because the dash gauge was pegging. So my question to the engine is "Are you friggin' getting hot or aren't you"...lol. Maybe I have a gauge that is not calibrated correctly because I now have the CTS impedance measurement and the infrared thermometer corresponding. Then I went so far as to use the temp probe on my multi-meter to measure the thermostat housing temp via direct contact and yip, it measured in the low 190's as well. So two gauges say its hot and three other tests say its not.

While I was doing these tests I noticed that the idle wasn't doing its little 32 second dip anymore? Now I didn't bridge the connector for the CTS as that wasn't what I was working on so I am curious as to what disconnecting the CTS plug did to change the idle?

The engine was hot when I shut it off and reconnected the CTS. When I started the car again the engine stumbled badly for about 5-6 seconds before quasi stabilizing. I am going to order a new CTS for the helluvit but was wondering if anyone knows the condition of the air / fuel when the CTS is not connected and not bridged. Is it putting the car into some other predefined state of fueling? Also noticed that the idle went up a little bit and the car smelled rich

Update:

I tried two different temp sensors to check and see if the original gauge did the same thing. Yip, with the original one and with a brand new one. The impedance was only at around 600 ohms on the CTS and the temp gauge in the car pegged. Did it with both sensors. Measured the thermostat housing with infrared gun and it was only showing around 160-170 degrees.

What controls the steps of the thermostat since we know that the gauge does not do a corroborated readout but moves in steps. Where is it getting that signal from?
The gauge sat just below normal for only a short while and then pegged quickly.
Very frustrating

 

The temp sender and the sensor, so the fact that your gauges aren't accurate will have no bearing on your issue. It's quite plausible that although the ECU is seeing one temp, the gauge could be reading a completely different value. Only what the ECU sees is important.

Does that help?

 

The thermostat is controlled by actual temp. If it's the original, it should probably be replaced, since it can be stuck open. Your engine would be running too cool. Not the cause of your problem, but it's easy enough to replace. Make sure you order a gasket as well.

 

Thanks Vee,

Yes, I get all that and I know the two are separate sensors.
The temp issue or at least the "supposed" temp issue is a completely separate issue I have been having next to the lumpy idle problem.

My post was just to say that as I was testing the CTS for the ECM, I noticed that the idle appeared more stable with the CTS unplugged and not bridged. I have now put a new CTS in for the ECM and the idle seems much more stable than it was before.

The actual car appearing to run hot can either be a gauge issue (not the sensor as I have been through two different new ones and the original with the same result) or as I discovered, my cooling system does not appear to be building any pressure.

Cheers
Bernie

 

While testing for the hot temps I was seeing, the thermostat was removed altogether. I have since reinstalled it and by my measurements, it seems to be opening around 195F. That's when the upper rad house begins to get hot.

B

 

Can the car enter closed loop with the CTS unplugged? I don't think so. The car will seem more stable because it's fueling based on preset maps, not actual conditions. You are probably running rich and your mpg is way down.

Did you try jumping the two contacts on the plug? I believe that sends a fully warmed signal to the ECU so that it can go closed loop.