Ross,

Many thanks for your empirical confirmation! We can now quote the manual with the confidence that a knowledgeable owner-mechanic has proven it to be true!

Cheers,

Don

 

Hmmmm, well, OK I'm back, had to work and take a quick overnight trip and seem to have missed some of the fun here.

Anyway, to bring everyone up to date, ra.stewart is Ray, nice to meet you all. I own a fleet of oddities and have had many in my life, and typically only farm out auto service work that I just absolutely can't do myself, like alignments, as well as fancy myself as being a pretty good home mechanic. While some of the suggestions I have had seem to be greeted with some skepticism (oil in the cylinders, etc.) I have personally used many gallons of Marvel Mystery Oil through the years on various cars and can say that it was vital in my old 2 cyl. Fiat 500's, which seemed to just love a squirt from time to time and a splash in the tank as well.

Now back to the demon possessed XJ6. I unplugged the cam sensor with no luck. I did manage to get it to run, badly, enough to move it and finally got a CEL code for mis-fire cylinder #1, but as bad as it was running it could have been mis-firing on more than 1 cylinder. My experience tells me it is more than a mis-fire on one cylinder, and my earlier observations of some iffy spark on all 6 coils makes me concerned with the power getting to the coils. I see basically battery voltage at the coils, but am considering hooking another battery up directly to the power wire going to the coils to supplement the electrical supply. I find it hard to believe that all 6 coils died at the same time.

Also, a u-pull-it scrap yard nearby says they have a x300. I am considering going and pulling the coils, ECU, crank and cam sensors, etc. just as spares. I hate to be a "parts swapper', but at the prices they charge you can't go wrong with spares. (that is if someone hasn't beat me to it)

I have not had time to go through the electrical manual to look at the shifter lock out problem, but wonder if my two problems are linked?


Also, a few of the fuses have plastic covers over them, black, yellow and orange. Anybody know why, what they signify and which fuse should have them?

Again, thanks for any input or help. Sorry if my questions generated controversy in some way. I am thankful there is such a knowledgeable and enthusiastic group here that is kind enough to help as I learn more about this wonderful, if demon possessed car!

 

I would put a fully charged battery, full of grunt, into the car and see what happens. These cars are quite "power sensitive" and a weak battery has been the cause of many electrical gremlins for owners in the past.

As for the plastic covers on the fuses, I think you are talking about the insulator/colour coded part of the fuse? This plastic part has a little lip either side, to facilitate grip, when removing the fuse. There is a plastic, tweezer like tool available to make this job easier, unless you have fingers like a midwife!

 

Thanks for your input. I put a new battery in with no success. I've added another battery via jumper cables and used my booster box, just to be sure I have enough power.

The covers I am talking about are orange in the attached photo. Not sure what they mean...or where they went. I pulled them off while checking all my fuses with my VOM.

 

I think those orange "fuses" are blanks, sitting in spare or empty slots. Just to stop gunk getting into the fuse box and to prevent fuses being put into these slots accidentally. Many models don't have all the same whistles and bells as others, but the wiring is there just the same, common to all models.

Just thought the battery issue was worth a mention and it's a bonus when a fix is that simple!

 

A good candidate for the symptoms you are seeing is the MAF sensor. I saw in one of your posts that you pulled it and looked at it. Did you do any tests? Ideally we would like to see the MAF readings that the ECU is seeing by using a diagnostic scan tool. Failing that you can do some basic testing at the MAF plug.

There are 3 wires. With ignition on, you should have B+ on Pin 1, Ground on Pin 3, and Pin 2 is the signal to the ECU. With engine at idle you would expect a steady voltage of around 1.2V, probably about 1.5v or 1.6v at fast idle on a cold start. If your voltage is way off or is fluctuating wildly then MAF could be your issue.

 

Brendan, Is B+ for the MAF battery voltage or something lower like 5V?

Cheers,

Don

 

Don, It's a fair question as you might expect a 5V Reference. But it is definitely 12v Battery Voltage.

The 12v is supplied from the ECU controlled relay and not directly from the ECU. I have also confirmed 12v on Pin 1 on my car with a meter.

Cheers

 

I've been concerned with the MAF. I took it out and expected to see something like in the XK8 we have or the various other cars , but there is nothing exposed. I'll check those voltages tomorrow when I can get it to run and see what it looks like. I have a code scanner, but nothing more advanced to check it with.

Thanks for the input and I'll post my results as soon as I can.

 

Thanks for the additional info, Brendan. I asked because I've learned that B+ is not always 12V or battery voltage. (I once built a pair of vacuum tube audio amplifiers with 6550 tubes running on a B+ of around 500VDC...you can bet I was REALLY careful with my wiring!).

Cheers,

Don

 

Don,

Yes the term B+ actually originated with old vacuum tubes that were used in radios back in the day. There were 3 batteries, A, B and C. The A+ supplied the filaments, the B+ was the plate supply and the C- was the grid bias.

It does not mean 12v, it means whatever is the battery voltage for the application so it could be several hundred volts in guitar amps for instance.

In cars it is the battery voltage which is generally 12.3-12.7 with ignition off and 13.5-14.3v while running, i.e. it's not a regulated voltage. In fact if you have a battery voltage of just 12v, many systems in the Jag may not work at all!!

 

6550 tubes! My Harmen Kardon A-50K used 6550's. Jaguars, vacuum tubes, sounds like a bunch of old timers!

 

Ray, If you still have that HK sitting around I'd be happy to take it off your hands!

And Allan, Don't get me started on guitar amps! As I sit and type I can look across the room and see two Fenders and a Mesa Boogie.... :-)

Cheers,

Don

 

Sorry, the HK is way in the past. I moved to a more modern (?) McIntosh MAC 1700 with only a tube front end/solid state amp. BTW, I had a Dynaco Mk5 (I think it was a 5, mono cube, heavy and generated tons of heat!) hooked up to the HK's blend center channel hooked up to a Heathkit knockoff of a Klipshorn. I wish I still had all of it!

 

Ahhhh. I well remember my dad's affection for MacIntosh amplifiers....back in the day of "Hi Fi" equipment. Thorens turntables, HK receivers, Ampex reel-to-reel, etc.
Dad loved his music and his equipment....although the neighbors were not always as appreciative :-).

It was just a couple years ago I sold off his record collection....about 3000 LPs ! I saved 100 or so of his favorites as momentos.

Thanks for the stroll down memory lane.

Cheers
DD

 

I picked up my appreciation for Hi-Fi from my dad. While everyone else's houses had blaring TV's, our's had music. I too sold off most of his LP's, keeping some as momentos as well. I love CD's in the car, but nothing sounds like vinyl through good old top-notch Hi-Fi equipment!

 

SACD and DVD-Audio have been my preferred formats for the past few years, but I'm just beginning to try the growing number of hi-rez download files. I recently noticed all my old vinyl in the attic and got an itch to recommission my old Sota turntable with Souther and Rega arms, so I'm trying to save up for a decent cartridge (sold the old Shure V15 years ago).

I had a McIntosh C20 pre and a pair of DIY McIntosh power amp clones I built and that system could astonish the uninitiated, but ultimately, with the powerful low end of modern music, I drifted toward high-end Class-A solid state (Pass Labs and Nelson Pass DIY).

Like I said, DON'T GET ME STARTED! Poor Ray still needs help with his Jag!

Cheers,

Don

 

Yeah, I guess we better get back to cars....

Funny how we all have these other shared interests as well as cars!

 

the covers denote airbag system fuses, and are covered to keep people from checking with a test light that COULD set off bags. A low impedance DVOM is fine though

 

OK guys, so I went out in the cold today to see what I could find on the XJ6. Well, I got her started and checked the MAF, everything looks OK there. While I had it running I was getting multiple CEL's, all relating to mis-fires. Then I noticed that my volt meter was sitting just out of the red! If you turn anything on, the charge light comes on, so now I'm thinking I have a charging system problem that has been masquerading behind running fault. When checking voltages not running everything is in the normal 12-13V range, once running it gets down in the 10.7V area. I guess it's time to pull the alternator and have it checked, although if it isn't charging full voltage, I'm guessing a bad diode inside, since the batteries I have are all new or fully charged. I'm also guessing weak charge, couple with old coils could be further complicating the situation.

Sound like I'm on the right path to you guys?

As always thanks to all!