I have an '85 XJ6 Series III. I have owned the car for 11 years and it only has 41,000 miles on it. The car has always been garaged and I drive it about 2-3000 miles/year. Except for this one problem, the car is in excellent condition, both cosmetically and mechanically. I have won several local concours events with it. My problem is the car will start without any problem, then it dies. When it first started doing this, it was intermittant. I could drive the car for 40-50 minutes without a problem - at highway speeds or in town, and the engine would suddenly just stop. If I was on the highway, I could throw the car into neutral and then turn on the starter and the car would re-start and be ok for awhile. If I was driving in local trafic, I would have to stop the car, then engage the starter and go on. Unfortunately the problem has become incresingly worse and more frequent. It is not a starting problem, the car always starts immediately, then it dies. Now the problem has gotten to the point that when the car dies, it takes many, many attempts to get the car running. Again, the engine starts immediately, then quickly dies. When it finally stays running, it may only run for a few minutes before it dies again. Any help would be sincerely appreciated.

rpfry

 

Remove the left side underdash panel and with the engine running gently tug/jiggle the wires at the back of the ignition switch. If the engine stumbles or dies, you've hit paydirt...you need a new switch.

And/or.....

Run a jumper wire from from the battery "+" post to the "+" post of the coil. If the car behaves properly then you know you have a problem with voltage getting to the coil....most likely the ignition switch as mentioned above.

Also....

Inspect/clean/tighten the wiring and connections at the coil, water rail sensors, firewall relays, and the injector ballast. Also check the bundle of ground wires at the rear of the water rail and the white/black wire that run aft along the water rail. That's the ECU trigger wire.

Check the ductwork between the air flow meter and the throttle body.

Be ready to check for spark/no spark next time the car is in "no start" mode. Although my gut feeling is an igntion problem you should check for fuel pressure at the same time if possible. Do you have a fuel pressure gauge?

Post back if you have questions or if none of the above helps.

Cheers
DD

 

It sounds like the same symptoms I had awhile back - engine dieing at highway speeds, and at other random times, but firing right back up. And getting worse. My fix turned out to be in the AFM (air flow meter) between the air cleaner and the intake manifold. I couldn't diagnose it so I had to break down and take it to a Jag specialist, and, if I remember right, he said that there is a metal arm, I think under a black plastic cover on the AFM, that sweeps around as the door inside the AFM opens and closes depending on demand. This arm was apparently low on pre-tension and would lose contact sometimes. If it lost contact the computer would regester this as no demand or something and shut the car down. He said he simple tweeked it a bit to add some more pre-tension to it, and I haven't had any issues (with this problem anyway) since then. If you didn't feel like trying to tweek on the AFM yourself then the only alternative I can think of is another AFM.

Good luck, that was the most annoying issue I've ever had with a car because it was so random.

Eric

 

Thank you Doug and Ronin. Let me tell you what has transpired with my problem today. Please note that this happened before I received Ronin response. Not being very mechanically experienced, I had a friend who is a pretty good amateur mechanic - and also owns a Series I XKE - come over and help me find the problem. We checked the ignition switch and coil and what other electrical wires we could see as per Doug's suggestions. The fuel pump also seemed to be working. So we were frustrated because the car would always immediately start - so we were getting spark and fuel - but then would die after about 5-6 seconds. I asked my friend if there could be a problem with the air flow meter because I remember another Jaguar friend mention he had a starting problem due to a faulty AFM. So we took the air filter off and looked inside at the air control valve. It seemed to open and close by pushing it with our hand inside the metal housing. So we started the car again with my friend looking inside the housing under the black plastic cover that Ronin descibes in his post. The valve opened slightly when I started the car, but then quickly closed after 5-6 seconds, and the engine died. We then took a ruler and manually pushed the valve open after starting the car, and bingo, the engine continued to run. So my friend said to look on line to price out new or re-manufactured mass air flow sensors, and then he left. I then checked the forum and found Ronin's post describing his solution. Now I have another question - Ronin said his Jaguar mechanic just 'tweeked' the pre-tension rather than buying another AFM. Does anyone know how to do this?
I'd like to see if I can do this rather than buy a new one - they aren't cheap.

Again, thank you for your help and your quick response to my problem. If anyone can explain how to tweek the AFM valve, I'd appreciate it.

Ray Fry
Atlanta, GA

 

I took his explanation to mean he physically bent the metal arm down slightly so that it wouldn't lose contact with the surface it was supposed to be touching.

I say this after talking with the guy, not physically opening it up myself, so take it for what it's worth. When I see him again I will try and confirm and/or get more detail.

Good luck!

 

This is a great post to archive for personal use later. Thank you for the dialogue, it is very helpful. I just replaced my air filter and took the housing off the clean it up and saw that flap and black box. Nice to know it can be the source of an "issue".