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Engine vibrating after warm-start

XJ4081
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Posts: 202
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Engine vibrating after warm-start

Postby XJ4081 » Sun Nov 05, 2017 9:41 pm

It's difficult to say whether it affects driving or not. As I said, even on low idle it accepts throttle with no problem and it does not feel hampered, but I, as the driver clearly feel the vibrations, passengers do not (at least until I tell them).
1993 XJ12

XJ4081
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Posts: 202
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Engine vibrating after warm-start

Postby XJ4081 » Sat Nov 18, 2017 11:23 pm

Today I found the time to remove the engine cover and inspect what is beneath and I finally found some cables lacking isolation. The single conductors seem to be intact, but that's maybe already enough to cause the problems I described?

Image

Image

One of the strands goes to the sparks of the first two left cylinders. The second one goes somewhere in the center:

Image
1993 XJ12

XJ4081
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Posts: 202
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Engine vibrating after warm-start

Postby XJ4081 » Sat Dec 09, 2017 1:59 am

Just setting up a list of parts to buy for ignition-renewal:

Distributor Cap JLM1909*

Coil-ignition DAC4608

Spark Plug EBC4021

Plug Lead Set LHD1509AA

Clip-cable DBC10203

Washer WA106041J

Anything missing?

Not sure if the cable on my third picture is one of the Plug Lead Set, I'd rather say no, but what is it then?

To get back to the injectors, you said when they are blocked or restricted there would be black smoke on idle, just wanted to confirm that this is not the case.

Also had no exhaust issues so far, the car just passed emission test in August (and it's not a VW Diesel, they really checked it thouroughly :twisted:).
1993 XJ12

pimgmx
Posts: 3217
Joined: Tue Jul 08, 2014 12:07 pm
Location: South East of the Netherlands

Re: Engine vibrating after warm-start

Postby pimgmx » Sat Dec 09, 2017 12:39 pm

XJ4081 wrote:Anything missing?

Distributor cap gasket, assuming it's not included with the dizzy cap: JLM1910.
Distributor arm. It's the combination worn cap/worn arm that causes the infamous 'Marelli effect'...
Image
Part number is JLM1911.
Ignition air filter: DAC4062
Image

See here: https://www.jaguarclassicparts.com/de/j ... -6-0-liter

Image


XJ4081 wrote:Not sure if the cable on my third picture is one of the Plug Lead Set, I'd rather say no, but what is it then?

It won't be: those kits only contain distributor-to-coil and distributor-to-sparkplug leads. The white wires in your pic look like the ignition amp-to-coil wires?
Part no 5 in the pic: https://www.jaguarclassicparts.com/de/j ... -6-0-liter

Image

Couldn't find a part number for the wires, sorry!
Plan B: test the wires with an Ohmmeter for resistance.
If they're OK: add heat shrink tubing if the wires are exposed (which I recall you said was the issue?).

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq

XJ4081
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Posts: 202
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Engine vibrating after warm-start

Postby XJ4081 » Sat Dec 09, 2017 11:23 pm

Thanks, Pim!

Ign to Amp makes sense, especially if that part below the red circle in Pic #3 is the ignition amplifier and the part below that the coil :?: . You can also see the naked cables belonging to that port in Pic #2, it's the all white conductors you can see there pretty much in the center of the pic, within the frazzled isolation.

The ignition amplifier module itself is no known source of error? Looks unpretentious, but is a costly part :? .

Can you maybe also recommend a V12-friendly spark plug wrench? The last one I possessed was only good for modern art after 3 out of 4 spark plugs :x . Or is the one from the vehicle tool kit sufficient?

BTW: JLM1909 is not available any more, SNG Barret only offers an aftermarket reproduction part, is that ok?
1993 XJ12

pimgmx
Posts: 3217
Joined: Tue Jul 08, 2014 12:07 pm
Location: South East of the Netherlands

Re: Engine vibrating after warm-start

Postby pimgmx » Sun Dec 10, 2017 12:17 pm

XJ4081 wrote:Can you maybe also recommend a V12-friendly spark plug wrench?

The one in the toolkit is up to the job. But...
I made my own tool for the front two cylinders, where accessibility is minimal and a regular plug wrench is not ideal. I bought a short 16mm socket and shaved off two sides on a bench grinder. I could then pop it in and attach it to the notorious 1B spark plug end, which was then removed with a regular spanner.
Alternatively, you could get a socket with a hex end, which is already designed for this type of use:
Image
(similar to the pic above, but shorter)

Pics of my home-made tool:
Image
(note: I ground it down further after this pic, so I could use a smaller-sized spanner than the biggish 21mm)

Image

Oh, and do gap those new spark plugs before you install them, I've had a few that were substantially off-spec when I unboxed them...

XJ4081 wrote:JLM1909 is not available any more, SNG Barret only offers an aftermarket reproduction part, is that ok?

It is of slightly lower quality than OEM, but it's basically the only part you will be able to find...
The OEM part has been out of stock for ages, chances that you will find a NOS part are close to zero.

And while I'm at it: some pics of my ex-DD6's ignition components, illustrating why these things need TLC.
Check those burn marks!

Image
dizzy cap

Image
rotor arm

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq

XJ4081
Snr Member
Posts: 202
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Engine vibrating after warm-start

Postby XJ4081 » Sun Dec 10, 2017 2:42 pm

Nice DIY tool, Pim. Let's see how far I get with the standard toolkit. I think there exist various types of cranked, long and short-necked wrenches, but you never know which one you can actually use, until you need it.

How can I actually check the spark plugs? And how big is the chance to get a malfunctional one? Are there suppliers or manufacturers I should avoid? Does SNG deliver other parts than Jaguar Classic parts?
1993 XJ12

pimgmx
Posts: 3217
Joined: Tue Jul 08, 2014 12:07 pm
Location: South East of the Netherlands

Re: Engine vibrating after warm-start

Postby pimgmx » Sun Dec 10, 2017 4:42 pm

XJ4081 wrote:How can I actually check the spark plugs?

I've never come across a non-functional spark plug myself, but hey, there's a first time for everything! ;)
Resistance check with an Ohm-/multimeter can be used in case you want to be absolutely certain.

A must-do is to check each plug's electrode gap against Jag's factory specs (0.6mm according to page 37 of NGK's catalog).
Weapon of choice for that task: a set of feeler gauges.
Image

Combine gauges to match the factory recommended gap and slide them between the lateral and central electrodes:
Image

This should be a snug fit, ie it should take some effort to slide the gauges in/out.
If the gap is too tight: gently open it by bending the lateral electrode away from the center; if the gap is too wide: gently bend the lateral electrode toward the central electrode.

XJ4081 wrote:Does SNG deliver other parts than Jaguar Classic parts?

Afaik both supply NGK plugs, which are OEM Jaguar on many models, not just the '40/'81. The correct XJ81 part is Jaguar part # EBC4021; NGK BR7EF.
I've heard mixed stories about Champion plugs, which were OEM at some point as well. I've stayed away from Champions and have used NGKs on all my Jags, never had an issue with them!

BTW: it might be worth shopping around, I found them faaaaar cheaper on eBay...

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq

XJ4081
Snr Member
Posts: 202
Joined: Fri Oct 23, 2015 12:12 am
Location: Germany (South-West)

Re: Engine vibrating after warm-start

Postby XJ4081 » Sun Dec 10, 2017 7:48 pm

Ok, I got it. I am surpised how cheap these spark plugs are. I remember I spent the same money on only 4 of them. Good to know, though I prefer to buy my parts at as few suppliers as possible, that reduces shipping effort and receiving 1 package is less stressful than 5.

Do I need any other special tooling or knowledge for changing the ignition parts? Or is it rather a simple disassembling/reassembling job?

Would be nice if I could also have a new exemplary of this mysterious lead for the ignition module, but could not find it anywhere :cry: . Their inner isolation seems to be visually intact, but even if Multimeter says it's ok, there remains an uneasy feeling about it.
1993 XJ12

pimgmx
Posts: 3217
Joined: Tue Jul 08, 2014 12:07 pm
Location: South East of the Netherlands

Re: Engine vibrating after warm-start

Postby pimgmx » Sun Dec 10, 2017 8:29 pm

No, no exotic tools needed!
Just your regular spanners/screwdrivers/etc will do.

I wouldn't be too worried about those 'bare' wires, I checked some engine pics of my good old Sovereign (yes I know, a straight 6, not a V12...) and ignition module insulation looked pretty similar to that on your 12-pot. Never had ignition issues with that car in the 4 years of non-stop daily driver usage.

Or as software developers say: "it's not a bug, it's a feature"... ;)

the daily: 01 S8 http://bit.ly/2kIwP4m
the tractor: 77 LaRo LW https://bit.ly/2Hr9n6y
the eyecatcher: 93 Insignia http://bit.ly/1iGrmsU
the GT: 89 XJS http://bit.ly/1WQGpC5
the project: 95 X306 http://bit.ly/1cW11DN
the pocket rocket: 97 Z3 http://bit.ly/12IfE7B
the ex: 93 3.2 http://bit.ly/14GTNrq