I was changing the thermostat and back-flushing the heater core on my 1996 4.0L Convertible. After I was finished changing the thermostat and had let the heater core back flush for a bit, which of course tends to spray water everywhere, I started it to bleed the air out and then check for leaks, and let it sit and idle. Which of course meant even more water which had splattered down onto the fan got slung all under the hood over everything. After about 10 minutes of idling it was just starting to reach normal operating temperatures when it suddenly died, no sputter, no running rough first, just died as though I had turned the key off!

It has not started again since... just cranks but doesn't even try to start. I had been doing it outside in the driveway to avoid water in my garage so left the hood up overnight so everything could dry and this morning still would not start. I have unplugged every connector under the hood I could find and sprayed both sides of each connector with fast-drying electrical contact cleaner/dryer leaving them unplugged for another hour afterward to make sure that stuff had totally dried (and it's sunny and very windy here today). After that I plugged everything back up and it still wont start.

There was no sign that any water at all got under the coil pack cover that says JAGUAR on it even though I did unplug and spray each of the connectors and when it still would not start I even pulled the coil pack off of the first plug which confirmed it was totally dry. I could hear the fuel pump running when the key was cycled but I still loosened the fuel rail connector, tuned on the key and it sprayed fuel. So I finally found my noid light kit and checked, no sign of a signal.

Now I am totally stumped, it was idling perfect, died just like I had turned off the key, and now no signal to the coil packs. Most likely from water/moisture getting somewhere but I am stumped since I have unplugged everything and even sprayed contact dryer and let them sit unplugged on a windy, dry day before re-plugging everything. I have now also went on to check every fuse and pull and re-plug every relay swapping the positions of the relays since they are all the same. I finally also pulled the round cover off of the dummy distributor and sprayed the contact dryer in there.

I am now totally stumped and need ideas.

Any clues, ideas, or suggestions?

 

Have you checked the condition of the ECU pins in the passengers side foot area? Could it be possible that water made it's way down there?

 

Have you checked the integrity of the connection on the crank position sensor which is naturally just behind the fan? If you've had water splashing around the front of the engine, that's the first place I'd start on an AJ16.

Good luck

Paul

 

I didn't since I wouldn't have assumed water would have gotten in there, but I guess I probably should. I do know the carpets are totally dry.

 

That was actually one of my first thoughts but was one of the things I unplugged, sprayed in the cleaner/dryer, let sit for hours in the wind, and then re-plugged. And the sensor itself was just changed in the fall of 2014 so less than 8k miles on it since then so I wouldn't expect it to go out again this quickly. Unless water getting in the connection could somehow short it and burn it out, though if they was that sensitive to water you'd think they'd go out all the time driving in the rain considering where they are located.

 

Went back and checked and no sign of moisture at all, whole area is bone dry.

 

One more thing I just tried is I plugged in my OBDII reader, I had before but only to check for codes (and there were none). But this time I set it to "Live Monitor" and cranked the engine. Two things, first off the reader told me that "Module 18: Calculated Engine Load %" was not getting a response and asked if I wanted to continue without it so I did, then noticed that of the two Engine RPM monitors neither showed any kind of reading even while cranking it. Now, the tach on the dash does momentarily jump up to about 1000 when I very first begin to crank it but then that also drops to 0. I'm not sure if the tach normally shows RPM's while the engine is cranking or not. Nor am I sure if the OBDII not getting a reading while engine is cranking is normal or not either, maybe it just doesn't start getting a reading until the car is actually running. Different models of cars do this differently and I'm not sure about the Jaguars. Does anyone know if these cars show a reading while cranking but before actually starting, and if they do, what would it mean that mine is not getting readings?

 

By the way; Does anyone know which sensor (Crank or Cam) sends the signal to the tach and which triggers the ECU to fire the coils or if it's the same one, and which?

 

Well, I just came in from putting in a new Crankshaft Position Sensor and it still will not get any fire, though the tachometer is now showing a reading while cranking.

So I pulled out the computer from the floor just in front of the passenger seat and checked it and it looks perfect, the pins are all straight and bright shiny clean. No sign of any moisture, and no sign there ever has been. Both the ECU side and the connectors side all look like they came off the showroom last week.

The only thing left that *I* can think of is the Camshaft Position Sensor but no one around here can get one without ordering it in which will not only take a solid week but it's also very expensive to be ordering without knowing for sure.


DOES ANYONE KNOW ANYTHING ELSE I COULD POSSIBLY CHECK OR TEST TO NARROW DOWN WHAT IS CAUSING THIS?



What about the security system?
The battery in my remote was getting weak and it went off twice on my trip last Saturday because it would set when I got out of the car but refused to un-set with the remote when I came back, forcing me to use the key to open the door which then set off the alarm and I had to cycle the key to get it to stop. It was running and had been idling for 10-15 minutes when it dyed so doesn't seem like it would have ran at all if it was the security system but at this point I'm grasping for straws... and did find a store yesterday with the right remote battery in stock so was able to set/unset it normally with the remote last night and this morning which you would think would re-set the security system if that had been the problem.

 

SouthernGypsy,

As you probably know the Cam Position Sensor does very little on an AJ16. It's only purpose is to signify if the cylinder is on firing or exhaust stroke so that the car can fire on the first turn. (Otherwise it might have to do 2 revolutions to work out the firing stroke). In theory, it could be disconnected once the car has started so I don't think a failure whilst running can cause the car to cut out. I might be wrong but I thought the car could start without out just by turning for a bit longer. As I said, I might well be wrong!

I don't know if that helps you at all.

Paul

 

Well, the parts store that said they didn't have a Cam Position Sensor called back right after my last post and said they DID have a rebuild kit for one (new pickup coil and you have to slide the shaft out to put it on) so I ran down and got that and just finished installing it and the cat still wont start!

Grrrrr! This is really getting annoying because that was the last thing I could think of and now I'm just hoping someone else has some other ideas.


Is there a way to test the computer?

If the Crank Position Sensor went bad, is there any way it could have knocked something else out that I'm not thinking of?

Could moisture still be somewhere grounding something out keeping it from starting? And what would keep it from starting it if were grounded out or shorted by moisture?

 

SG,

Silly question, maybe, but have you pulled a plug and confirmed that there is no spark on that plug when cranking?

Paul

 

Yes, early on, and then have been using a noid light since.

 

Well, here is a strange ending to this, though not sure how much of a "solution" it actually is...

A friend of mine who also has a '96 AJ16 4.0L and is an electrics technician at the local hospital (maintains all their electronics monitors, he's also good for fixing car stereos) came over and helped me tinker on mine for another couple of hours, we both re-checked everything and went back over everything I had already done double checking everything... Including re-checking the ECU connections, which still looked like brand new with no sign of moisture or that there ever had been moisture. Car still did not start.

Then on a wild whim and with no other options, he said lets make sure the ECU didn't just burn out (something I'd already told him I was afraid may be the issue at that point, though don't know what would have caused it). So very very nicely, he said no harder than they are to get out let's just pull his and put it in my car..... My car started right up! He said really confusing because he pulled the cover off of my computer and said it's as pristine inside as outside, so on a whim he put the cover back on and plugged my ECU into his car, and his car started right up too!

So now we're both scratching our heads... So we decided to swap them back, and BOTH cars still run fine now!


Just got back from a test drive following each other up the road and back and both cars still run fine, like nothing was ever wrong.

WTH?!?!?


*rolls eyes*

 

Is it conceivable that the ECU got wet?? lost its memory and by unplugging and replugging in it rebooted and lo and behold it works.

I am no electrical wizard but even with my computer sometimes I unplug or reboot and all is well.

Good Luck going forward

Softball Paul

 

It was totally dry with no sign of moisture, and by that point I had un-plugged and re-plugged it several times, as well as having the battery disconnected several times including overnight the night before but still wouldn't start even just before we swapped them. That's why it's confusing.

 

Hi!
I bet the process of removing the ECU from your car to install the ECU from your friend car did a "cold boot" on the ECU's
and other engine management systems. Your friends ECU may have even caused a factory reset on some engine management settings.
And by putting the ECU's back into the respective cars the reset settings renewed
the car's factory settings.
As a long time computer server tech I followed a rule,"When in doubt reboot" and
"when in doubt, whup it out !" It seems that you followed both of those procedures.

Happy Trails and P O R - Press On Regardless !