Oh, absolutely I will. Everybody has been so kind and helpful, it will be the least I can do to explain how everything pans out. Oh, and sorry for the delay, I have been tied up for the whole day.

By the way, more as a matter of interest, or as an update as to what is going on, I have contacted Jaguar, and they have sent me a screen shot of outstanding issues on my car, stating, there is nothing outstanding. This is true, in that this is clearly what it says on his screen, against my car, meaning there is no recall, however, what he didn't mention in his email, is that in another section, which he included for me, perhaps by accident, it says, "There is a concern on the vehicle that needs rectification." Now the choice of wording here is key, I would suggest, in that it says there is a 'concern'. This is exactly the wording in the TSB. "A concern has been identified with the operation of the throttle, etc, etc." I even thought when I read the TSB, 'concern', heck, that's a bit of an understatement, lol.

Anyway, I believe, this is the very same concern, and that it is still outstanding on my vehicle and I have just gone back to him to ask him to confirm what this 'concern' on my vehicle actually is, and to answer my original question, which as of yet he has not, does the TSB actually relate to my car. I think it does, but I would like Jaguars confirmation, of course.

I'll report back as things develop.

Cheers

Sutty

 

If the TB is failing it will not cause the engine to stop or not turn over. You don't actually need a throttle body to engage the starter; it will engage but of course the car will not start. I'd really look into the inertia switch as the cause since if it is tripped the engine will stop and the starter will not engage. The switch shuts down the car if in an accident. Just poking the button might just stop the problem or it seems that if you connect pin 1 & 3 on the connector the switch will be bypassed and in the "on" position. If it was me, I'd buy a switch and install it before fooling around with anything else. I had this problem on a friends truck I was fixing and the symptom was exactly like your car. Tried a number of other things first of course!
(The switch is shown on schematic 2.1 of the electrical schematic manual. Do you have that PDF? I'd expect it's available somewhere on this forum....If you cannot locate it, let me know and I'll attach it to this thread.)
Of course it may be something else but I eliminate this first.....

 

Throttle cleaning completed, taking me about an hour. Probably is a 15 minute job, but I went at it very carefully, and, everything was much more stuck together than for the guy in the video. Consider that everything I just moved, had perhaps not been moved for twenty four years.

A point of note, that gave me a small issue, was that the rubber seal stayed in place on the top of the throttle body, as can be seen from the 'before' photo below. This caused me a few minutes difficulty because there is no way to push them back together, if the seal is in place on the throttle body. After I felt at it, and looked at it more closely, I saw it there, and removed it, fitting it into the end of the pipe, at which point it became a very simple matter to push them back together.

I felt like I would have liked to have put a wipe of oil on it, to help, a tiny amount, but I didn't know if I should. It pushed on fine, but I worried that without lubricant, maybe it could damage the seal. I also considered a teeny bit of washing up liquid, but again, I didn't know if this would compromise the seal, so I didn't. In the end, it appeared to be no issue, but might be nice to know if either if those things can be done, for a really easy slide fit.

Also made a mistake, in that I got it all back together, looking proudly at my work, and then went to put my tools away and noticed the large jubilee clip on the workbench. I couldn't believe how stupid I was, but I thought I'm not taking that apart again just to get that on, unless I have to, so I turned it until it fully opened, and put it round the pipe at a sort of angle, and I barely had to bend it at all, or at least not past its elastic limit, so when it closed squarely around the pipe, it very nearly met up anyway. Fed it back in, would it nearly tight, jiggled it for position, and then tightened it properly, and all was well. What a prat though, considering I was meant to be trying to be super careful.

New breather pipe had arrived, and was fitted, and because I had all this apart, I put a new air filter in too. The one I took out was clean, but I thought, what the heck, it's cheap enough, and even if clean, the old one was very old, so perhaps the integrity could be compromised?

I took a photo of what it looked like 'before', and what was on the rag, after I'd done it, but then in my excitement, I forgot the 'after' shot, which is annoying, but rest assured it now looks a lot cleaner, as should be obvious from the photograph of the cloth. It should be noted that the other side of my cloth is the same, so double the dirt you can see there. Although dirty, it surprises me that such a relatively small amount of residue can cause this valve to stick. I bet Jaguar were surprised too, when they first worked out the issue.


Thanks to having cleaned it only with petrol, as advised above, there was no starting issue at all, unlike in that video. I just started it normally and have been for a very short ride, just to check it, and it is running just fine. In a few hours, at midnight, I will be going for my proper test to try and invoke the fault. I'm hoping the next post I make, in a couple of hours, will be that I could not invoke it at all. Next motorway junction is 9 miles away, from where I join, so I ought to be able to do the test about 50 times, or more, during that out and return trip, as long as it's quiet enough. Obviously I don't want to be doing it if there is someone near, so it might be tricky to find a space, as it were, but we'll see. Not comfortable doing it on a normal road, late though it is, because few are suitable, and none near me is equipped with a non running lane, so motorway it is.

Wish me luck.




EDIT: Oh, I forgot, finger pressure is more than adequate, to hold it open, whilst cleaning, with no risk whatsoever. Maybe a little trickier to hold it, whilst getting the cloth in there, but still, it was easy enough, so no need to stick anything down, other than a finger.

Cheers

Sutty

 

Hi David

Thanks for the reply and the offer of help tracking down the appropriate document. I do have it by the way, but thanks all the same. I realise the throttle body would not be required to turn over the engine, but I have not described that the engine will not turnover, or that it will not start, indeed just the opposite. The TSB referenced by Tusk, not too far back in this thread, exactly describes my issue. To quote its first paragraph:

A concern has been identified with the operation of the throttle on a number of 1997-98
MY XK8, 1998 MY XJ8 and 1998-99 MY XJR and VDP SC vehicles. Under exceptional
circumstances this concern could cause the engine to cut out, although the engine will
continue to be driven by the road wheels through the transmission and drive the
ancillaries, so there will be no loss of power steering, brakes, air conditioning, etc. The
engine should restart without difficulty once the vehicle has come to a complete
standstill.

As you can see, the TSB even describes no difficulty in restarting, exactly as experienced by both my father and me. I've no doubt a very similar fault could occur, if someone had an intermittent fault with the inertia switch, as pointed out earlier by aquifer, but the particular way in which this actually happened to me on the two most recent occasions, match exactly with what tusk, others, and the TSB describes. Tusk absolutely nailed it when he described that it happens, infrequently, when you fully lift off the throttle. Jaguar's fix, for my VIN, is to replace the throttle body. Tusk's fix, and others, in the absence of support from Jaguar, on this 24 year old car, is to simply clean the inside of the throttle body.

I may yet get the throttle body replaced, free, by Jaguar, I'm fairly hopeful, but prior to that happening, I have gone for the clean.

One last thing about the inertia switch, I don't know, but I would strongly suspect, that had the inertia switch activated, even if briefly, it would make a log entry, had it shut down the car, but there are no important log entries, according to Tusk, who has looked at my attached scanned log.

 

Tried the lift off test on the motorway, as Tusk suggested, going at 11:30PM, and could not invoke the shut down. 75 times I tried the test, if truth be known. 60 mph, lift off fully, slowed to 55 mph, and then go again to 60 mph, then lift off fully, repeat ad nauseum, lol.

I may have felt a little sick, but the car never missed a beat. Seems to me like it's solved.

Still hopeful that Jaguar will come through, and replace the hardware. I'm thinking that file note on my car's VIN record is golden. See snipped section of his Jaguar screenshot below:



Remember, the TSB refers to this problem as a "A concern has been identified."

If Jaguar help, I'll be sure to update the thread, and praise them accordingly.

Cheers all.

Sutty