I know it’s not the same problem but on early years there was a TSB talking about engine harness damage from a cable clip. As your problem is intermittent may be worth a look?

http://www.jagrepair.com/images/TSB/...%20Harness.pdf

 

always worth a look.

on the note of wiring. i know that there is broken insulation on my ignition coil wiring. (which i have reinsulated) how would i go about re-making this section of the harness with fresh wire as opposed to just insulating tape?
anyone know what the plug type on the coils is so i can get new plugs?
i assume the best bet would be to cut the harness near the back of the engine and run new wiring from there?

**just checked. clip is gone. wiring is seemingly insulated. maybe at some point it might be worth removing the outer electrical tape and checking the wires. but not when its cold and dark night outside.

 

Where is the preferred place to get coils from and what ones?
seen lots about all of them being ****

 

@katar83 i was not able to get obd data as it was only an issue when trying to start so my dongle did not get any chance to connect.
i went to drive to work today.
car started and drove perfect initially.
then when i tried to take off from the lights after a little bit it just died.
no bad running or anything just died.
then when i went to start it did not want to start and took a while to go.
then it was missing horribly.
had to restart a couple times with heavy throttle to get it to smooth out and run.
after this however for the rest of the drive it was perfect.

makes it really hard to know anything from data perspective when it is just suddenly bad then good again.

but yes i could clearly hear and feel the misfire on this occasion

 

This is how I would do it...and I've done this for my TPS...and EGR, just because they share some wires.

1. I would buy correctly colored SXL wire. eBay can sell it to you in the color and lengths you want.
2. I would recommend Corsa Technic to buy wire harness parts.
3. I would order six of the connectors for the coil heads, Sumitomo 6195-0003 is the part you want....I believe.
4. Buy the OTHER end that connects into your Econoseal III 344111-1 ECU harness. Order the pin, and the seals. Make sure you have a crimper for this.
5. I think the other wire at this harness is ground. Check that before you do any of this.

I'm not recommending that this will solve your problem, but if you're looking for spend some quality time with the Jag...

Replace each wire one at a time. You can pull all of them through together, but just take your time and connect one wire at a time.

 

yeah the doing of wiring is not an issue. I know all that.
thanks for letting me know what the plugs are.
for now i will just strip it down and reinsulate all to make sure all is good.

i was thinking tho to cut harness behind engine and install an easy to access connector for if and when ever needed.
using of course waterproof connectors.
but yeah thats a bigger job for another day.

 

It would probably be best if you could just drive with OBD connected and running so data could be saved on your device(one that could do that ideally) so when it dies you can go back to it and see what was off just before it started running badly.
Re coils, if you have a spare car just use the spare car coils, I know you said it doesn't run but remove them all from the spare car and just test each coil individually in your running car, it idles fine most time so you should be able to test the spare car coils in it one by one, if the car starts badly with any of the spare car coils you'll know its bad, try to get a coil that isn't cracked ideally, if they are, cover with a bit of tape or a heatshrink and dielectric grease. Once you're happy with ideally TWO coils from the spare car, test them in your car starting with the cylinders closest to the windscreen. See if it improves.
New coils are a hit and miss, I don't think we had good 3rd party coils available since QYL stopped making them and I've bought the last set of them from them on the planet apparently.
Your best bet would be to source a used but new Lucas coil, Jag uses them today but they stupid expensive from Jaguar. They normally have a green Jaguar sticker on them. A good quality 3rd party coil normally has brass coloured spacers and a plastic tab through the glue in the middle of coil body. The cheapo ones don't have that tab and usually don't last long.
Just as a test I'd also swap the MAF from your spare car to see if any improvement, that 0.1g value at idle in your OBD would otherwise bother me.

 

already swapped maf back and forward a few times in the past and no difference whatsoever.

we really need a good source of aftermarket coils.

before i do anything car will be off the road for a few weeks
no time to work on it for a couple of weeks.
go to fix the coil wiring. i had a look at it tonight and removed dried cracked electrical tape that was covering dried cracked and missing insulation wire.
relised that i have run out of cloth electrical tape so got to ait for that to come and re-insulate the wires.

are these coils from berkshire good anyone know?
https://www.berkshirejagcomponents.c...MejbZ5ECHtAaCl
or any of these from sng barret?
https://www.sngbarratt.com/English/u...rnedDown=false

it will work out to be about AUD$400 to get the coils but if they are going to be good coils it will be worth putting the $$$$ aside.

 

Been busy on the weekend and it’s dark when i get home in the afternoon so its tough trying to do anything but i have been working on repairing the wiring for
my ignition coils.
so i stripped back all the crusty dried electrical tape on them, and exposed all the cracked insulation some small sections of fully exposed wire with no insulation.
so i have put some silicone around the plug connections to insulate all there and am using some soft cloth heatproof electrical tape to reinsulate all the wiring.
little bit time consuming but worth it.
none of the actual wires are damaged, only the insulation.
currently done cyl 1,2,3,4.

 

Did you use non-corrosive formula silicone? As regular ones are acetoxy cured and aren't a good choice for sealing the open wires. Best choice to repair a small insulation strip is a liquid tape (like StarBrite or similar).

 

honestly not something i thought about.
but it is JB WELD marked as sensor safe. so should be no problem in that regard
i was going to use liquid electrical tape but mine was old and useless.

 

so swapped the coils. tried multiple combinations and all lead to same result.
car idling ok. start to rev it and then it hits a spot where it stumbles. there is a lot of unburnt fuel and **** out the exhaust at this point.
something is causing it to intermittently over fuel.
really not sure what.
going to change the fuel filter again but that will not do anything.
watching the fuel pressure gauge and the is no issue there at all when it stumbles or not.
there is lag on my obd app so can't really see there anything.

 

MAF from A-Premium.
thoughts? never heard of 'em
https://www.ebay.com.au/itm/27617856....c101506.m1851

i don't wanna just fire the parts cannon but i feel i have no choice.

 

Took the plugs out and cleaned them yesterday.
Ran the car for less than one hour and have taken them out again.
my god they are black as.
shows just how rich it is running.

how long after shutdown should car maintain fuel pressure?
not sure of how quickly i should see it drop before suspecting leak.

 

G’day Spud,

I dunno whether this is relevant but I had an SIII XJ6 years ago and it ran as rich as and it was a dodgy coolant temp sensor telling the ECU that the engine was stone cold when it wasn’t.

it always started OK then ran like a hairy goat when it got up to normal temp.

Cheers,
Jeff.

 

coolant temp sensor seems to work.
car seems to run worse when cold if anything.

So after changing plugs, changing fuel filter, re doing coil wire, swapping coils it seems to be running ok.
for now.
who knows how it will go.
fingers crossed.

the coils in the car previously were marked as made in japan where as the ones now are unmarked so probably cheapos. But will keep a watch and if need be i can mix an match.

 

That's JUST a pressure gauge right, it's not increasing the pressure? Even accidentally?

Trying to think of intermittent problem's causes is such a pain. There was really only one time I caught my Jag running stupid rich. The cats had started faintly glowing, they were HOT. Since then I did a lot of work sealing any and all leaks. Weirdest ones were the EGR tube had holes and the exhaust headers warped, both letting fresh air in. The O2's presumably saw fresh air and added fuel. I'm assuming you checked through the intake for vacuum leaks by now?

 

just a gauge.
the adapter tap just has the fuel pass straight through. if anything the adapter is slightly more open and wider than the rest of the line so certainly nothing to restrict pressure at all.
the gauge was also installed to help diagnose this issue so certainly not a cause.

intermittent problems really do suck. so hard to diagnose and can take time to have any idea if what you have done has made a difference or not.

i used a smoke machine to check for leaks. found one near the brake booster line and one other. sealed those up. also used a bit of vasoline when i put the air ducting back in as there was some slight leaking around the clamps. tested and sealed perfect. no air leaks.

 

Those spark plugs you have pictured are extremely black & sooty, your car is never going run well with spark plugs in that state.

I have had plugs in that state when excess oil has leaked through from the plug/coil tubes and yes, the engine performed terribly, luckily the first thing I did was check the state of the plugs.

Your efforts appear all about solving air/fuel mix, have you considered a good compression test etc.

you perhaps have oil entering up past the piston rings.

I note in January your post “Thinking of engine rebuild or engine swap are my only options” and mentioned leaking valve stem seals.

Just as a matter of interest, I recently fitted extractors on my XJR and was very pleased with the results, the engine appears much more responsive.

I also took the opportunity to install an extra 02 sensor which connected to an air/fuel ratio gauge.

I was also pleased with the results, my engine consistently running at 14.5 to 15 air/fuel ratio.

Pictures of the extractors are attached including one with heat shield I fabricated to suit.

The extractors were sourced from David Austin in the UK, he was a delight to deal with and I am pleased with the product.

John Herbert
1996 XJR

 

oh yeah of course.
did you read how i said they were that black after only running the car for one hour after cleaning them!!!!!.
how they get that black that quick is big big concern.
I hope i am slowly making progress on this.

I had big problems with plugs swimming in oil back when i got the car but i since restored my valve cover and that issue is no longer there.


I need to get my hands on a compression tester to do it again.
I can't remember the exact results but i did a compression test early in 2023 (approx 15000 km ago) and all was very good at that point.
I am only speculation of course but do have thoughts of potential internal engine damage. the car does have almost 380000km on it.
getting increasingly concerned that internal damage is where i am at as i keep coming up fruitless with all other avenues.

I do love those headers and would love a set.
I saw David's post on them some time back and wanted a set but just can't afford to do it anytime soon.
potentially maybe 6 months away i can.
how much did it end up costing you to get them shipped here?
If i ever do get them sorted for myself i would be interested to hear more about how you set up the AFR gauge and how you sorted the heatshield as that was my biggest thought with them.

I have a new MAF coming and was considering getting some rebuilt injectors (even though i cleaned mine recently they were not properly flow tested) however once again that is money i just do not currently have.
My financial situation will change soon which will help a lot with getting more done.