1994 XJ81 - Needs TLC
Discussion
Sorry if my first post shouldn't be in the Readers cars section, but I am now the proud but apprehensive owner of a 1994 XJ12.
Oh and if I mix between UK and US terms I have been out here in Utah for the past 6 years so things are all merging together.
This car has been for sale for the best part of this year and I kept coming back to check on its progress even thought initially I really wanted an X308.
There was something about this one, could be that it looked in amazing condition for a 94 or just the fact it is a V12 but I kept watching.
Unfortunately it was always up for far to much money (I think it was at over $16K at one point) and although in the same state as myself it was still a 4 or 5 hour drive to view.
However while travelling for work, I noticed that they had dropped the price to one I was willing to pay, but I was now going to be in 3 different states and none of them where the car was located. I started looking to find someone local to inspect the car, but as it was in a small town I half expected all the mechanics to know each other and while debating on what I should do the car sold.
What I didn't know at the time was the new owner was my wife! She arranged for an inspection and her family to collect the car for my Birthday/Christmas.
So now she sits in my garage.
Well the engine is strong, no obvious signs of rust, it was a California car up until around a year ago, with very low mileage.
However the low miles may be the cause of the 2 big issues I have to resolve.
The first, not totally unexpected was a failure to pass the emissions test here in Salt Lake, It had a few issues in California too but always passed within a few days so I put this down to the low miles and needing a good run.
But since driving around, I have noticed that the idle is high, around 1200 rpm when warm and only dropping to 750 when stationary and in drive.
So my hope is, if I can get the idle back down to where it should be that will hopefully help on the path to passing the emission check. (She was fine at 2500rpm)
While I wait for a service manual to arrive, I am looking for advice as to where I should be starting. I have new HT leads, rotor arm and distributor cap.
Are there any recommendations as to the best spark plugs for the V12?
The second issue is one that decided to show this morning. The transmission/gearbox light has lit. No errors are showing on the onboard VCM though. Hopefully this is due to her being sat for a while with little movement as the snow has just set in and I'm not taking her out in that.
I only have one photo at the moment, unless I can find some of the old sale pictures.
Thanks
Andy
Oh and if I mix between UK and US terms I have been out here in Utah for the past 6 years so things are all merging together.
This car has been for sale for the best part of this year and I kept coming back to check on its progress even thought initially I really wanted an X308.
There was something about this one, could be that it looked in amazing condition for a 94 or just the fact it is a V12 but I kept watching.
Unfortunately it was always up for far to much money (I think it was at over $16K at one point) and although in the same state as myself it was still a 4 or 5 hour drive to view.
However while travelling for work, I noticed that they had dropped the price to one I was willing to pay, but I was now going to be in 3 different states and none of them where the car was located. I started looking to find someone local to inspect the car, but as it was in a small town I half expected all the mechanics to know each other and while debating on what I should do the car sold.
What I didn't know at the time was the new owner was my wife! She arranged for an inspection and her family to collect the car for my Birthday/Christmas.
So now she sits in my garage.
Well the engine is strong, no obvious signs of rust, it was a California car up until around a year ago, with very low mileage.
However the low miles may be the cause of the 2 big issues I have to resolve.
The first, not totally unexpected was a failure to pass the emissions test here in Salt Lake, It had a few issues in California too but always passed within a few days so I put this down to the low miles and needing a good run.
But since driving around, I have noticed that the idle is high, around 1200 rpm when warm and only dropping to 750 when stationary and in drive.
So my hope is, if I can get the idle back down to where it should be that will hopefully help on the path to passing the emission check. (She was fine at 2500rpm)
While I wait for a service manual to arrive, I am looking for advice as to where I should be starting. I have new HT leads, rotor arm and distributor cap.
Are there any recommendations as to the best spark plugs for the V12?
The second issue is one that decided to show this morning. The transmission/gearbox light has lit. No errors are showing on the onboard VCM though. Hopefully this is due to her being sat for a while with little movement as the snow has just set in and I'm not taking her out in that.
I only have one photo at the moment, unless I can find some of the old sale pictures.
Thanks
Andy
Well it does feel like there is a slight missfire on one bank, you can feel the car jolt when idling and a pulse in the right hand exhaust when it happens.
I am now wondering if the garage turned up the idle to try and hide it.
I now need to contact the mechanic my wife took the car to for it's failed inspection as he did a few checks. Apparently checked the pugs, but I dont know if he did them all or just a quick check of the easy ones to get to.
I am now wondering if the garage turned up the idle to try and hide it.
I now need to contact the mechanic my wife took the car to for it's failed inspection as he did a few checks. Apparently checked the pugs, but I dont know if he did them all or just a quick check of the easy ones to get to.
Started on the task of replacing the plugs and wires etc and found that the insulation on the injector and coil wiring has started to fall away.
Eventually I will have to replace the loom but for now I will have to reinsulate and hope it is only the insulation where it is exposed and not further into the wiring.
I have to get through emissions by the end of January or I think I have to pay all the registration fees again.
Eventually I will have to replace the loom but for now I will have to reinsulate and hope it is only the insulation where it is exposed and not further into the wiring.
I have to get through emissions by the end of January or I think I have to pay all the registration fees again.
Welcome ! We call that Jaguar series the XJ40. V12s were pretty rare in the UK. My first Jaguar was an XJ40 Sovereign (4litre I6).
A useful device for tracing idle misfire on V8s and V12s is an infra-red pyrometer. Point it at each exhaust port in turn and the coolest one(s) is/are the faulty one(s).
A useful device for tracing idle misfire on V8s and V12s is an infra-red pyrometer. Point it at each exhaust port in turn and the coolest one(s) is/are the faulty one(s).
very nice. I love the V12 XJ40 cars. Any more images??
As with other engines, be methodical and patient and you'll get there.
Who did the engine management system? That might need looking at too, but usually they adjust depending on input,
so work through what you're doing.
Oh, by the way:
As with other engines, be methodical and patient and you'll get there.
Who did the engine management system? That might need looking at too, but usually they adjust depending on input,
so work through what you're doing.
Oh, by the way:
lightweight73 said:
What I didn't know at the time was the new owner was my wife! She arranged for an inspection and her family to collect the car for my Birthday/Christmas.
So now she sits in my garage.
Thats no way to threat any wife, unelss the garage is carpeted and has at least one window So now she sits in my garage.
I had one almost exactly like that - XJ40 6.0 V12 in that same colour. Except it was a Daimler, so some of the trim pieces and badges were different.
Absolutely epic cars. I still miss mine today. As an aside, of all the Jaguars I have owned, it is the one that drew the most comments - and for some reason almost everyone wanted to buy it! Why can you never find those people when you actually come to sell it...
Absolutely epic cars. I still miss mine today. As an aside, of all the Jaguars I have owned, it is the one that drew the most comments - and for some reason almost everyone wanted to buy it! Why can you never find those people when you actually come to sell it...
A few more photos. Taken from the dealer's ad.
I don't have any others at the moment other than ones of the engine bay so I know where things go.
The wood is starting to lift on the ski slope and the doors and tables have a few cracks. But not bad for the age.
The leather will need work, especially on the drivers seat. The bolster has lost all of its covering.
I haven't found any rust so far, but I may just not be looking for it..
I don't have any others at the moment other than ones of the engine bay so I know where things go.
The wood is starting to lift on the ski slope and the doors and tables have a few cracks. But not bad for the age.
The leather will need work, especially on the drivers seat. The bolster has lost all of its covering.
I haven't found any rust so far, but I may just not be looking for it..
Replaced dizzy cap and arm, replaced HT leads and insulated the exposed wires. Not replaced the plugs yet and I was paranoid in stripping them when they wouldn't budge.
Will have to soak them in penetrating fluid. Any recommendations?
But no noticeable misfire and for some reason the idle is down where it should be. So some progress.
Will have to soak them in penetrating fluid. Any recommendations?
But no noticeable misfire and for some reason the idle is down where it should be. So some progress.
These engines are very tough, particularly the 6 litre version in the XJ81 and onwards. I'm not surprised your ignition system refresh sorted it out, the plugs will likely be ancient too. As you may have noticed/read changing the two by the air con compressor is a right pain.
The biggest headache with maintaining them is some of the weird old school 'features'. The idle air control system using a wax valve into one manifold that then relies on the balance pipe to get air to the other manifold confused me, I couldn't understand why at idle one air intake was flowing a lot and one wasn't flowing any. When I thought about it the answer was obvious (having been told), but luckily there are some very knowledgeable people on here to help!
The biggest headache with maintaining them is some of the weird old school 'features'. The idle air control system using a wax valve into one manifold that then relies on the balance pipe to get air to the other manifold confused me, I couldn't understand why at idle one air intake was flowing a lot and one wasn't flowing any. When I thought about it the answer was obvious (having been told), but luckily there are some very knowledgeable people on here to help!
I am still wondering about the 2 under the compressor. I have read that you can just loosen the bolts and let it flip forward (not sure how much faith I have in that now though as it listed half the nuts in SAE sizes when they are all metric.
The other option is to remove the belt but no auto tensioner on there.
This is going to be a great car to learn on!
The other option is to remove the belt but no auto tensioner on there.
This is going to be a great car to learn on!
Lovely car Lightweight, 
but then as Mandy Rice is oft' quoted " he would say that!" 
You have a trim combination that many of us the UK would deem to be the best i.e Jaguar + Autolux Daimler seating and of course you have the creme de la creme (if you excuse the cat pun) with the V12
Valuations on the '40 are all over the place but they are definitely on the up for sure; buy the best you can afford and enjoy.
Misfire on a V12 is very common apparently and can also be dangerous causing engine fires.I'm not clued up on the Magneti Marelli issues but the lads across on XJ40.com certainly are - they're a really friendly bunch and you'll find a warm and very knowledgeable welcome .
Look forward to hearing more.
Best
Carsie ('40 Supercharged Build)
but then as Mandy Rice is oft' quoted " he would say that!" You have a trim combination that many of us the UK would deem to be the best i.e Jaguar + Autolux Daimler seating and of course you have the creme de la creme (if you excuse the cat pun) with the V12
Valuations on the '40 are all over the place but they are definitely on the up for sure; buy the best you can afford and enjoy.
Misfire on a V12 is very common apparently and can also be dangerous causing engine fires.I'm not clued up on the Magneti Marelli issues but the lads across on XJ40.com certainly are - they're a really friendly bunch and you'll find a warm and very knowledgeable welcome .
Look forward to hearing more.
Best
Carsie ('40 Supercharged Build)
I'm still waiting for account on xj40.com to be approved.
Signed up before Christmas and didn't want to hassle over the Christmas break. Then the servers seemed to crash so probably bigger fish to fry than a couple of forum join requests.
-edit- looks like my login has been approved.
Signed up before Christmas and didn't want to hassle over the Christmas break. Then the servers seemed to crash so probably bigger fish to fry than a couple of forum join requests.
-edit- looks like my login has been approved.
Edited by lightweight73 on Wednesday 3rd January 02:01
Carsie said:
Lovely car Lightweight, but then as Mandy Rice is oft' quoted " he would say that!"
You have a trim combination that many of us the UK would deem to be the best i.e Jaguar + Autolux Daimler seating and of course you have the creme de la creme (if you excuse the cat pun) with the V12
Valuations on the '40 are all over the place but they are definitely on the up for sure; buy the best you can afford and enjoy.
Misfire on a V12 is very common apparently and can also be dangerous causing engine fires.I'm not clued up on the Magneti Marelli issues but the lads across on XJ40.com certainly are - they're a really friendly bunch and you'll find a warm and very knowledgeable welcome .
Look forward to hearing more.
Best
Carsie ('40 Supercharged Build)
Do you have an update on your build and the URL to catch up? but then as Mandy Rice is oft' quoted " he would say that!" You have a trim combination that many of us the UK would deem to be the best i.e Jaguar + Autolux Daimler seating and of course you have the creme de la creme (if you excuse the cat pun) with the V12
Valuations on the '40 are all over the place but they are definitely on the up for sure; buy the best you can afford and enjoy.
Misfire on a V12 is very common apparently and can also be dangerous causing engine fires.I'm not clued up on the Magneti Marelli issues but the lads across on XJ40.com certainly are - they're a really friendly bunch and you'll find a warm and very knowledgeable welcome .
Look forward to hearing more.
Best
Carsie ('40 Supercharged Build)
That's a lovely looking XJ12 - from the photos it seems to be in tremendous condition. You are correct to call it an 'XJ81' - which is the code name Jaguar gave to the standard wheel base V12 - XJ40 was the code name for the six cylinder cars only. I do tend to call them V12 XJ40s though, even though this isn't correct!
You probably know this, but there are several forums which have quite a lot of expertise on the XJ40/XJ81. There is www.xj40.com which you have already joined, but also worth joining are the Jag-lovers forum https://forums.jag-lovers.com/c/xj40 and Jaguarforums.com https://www.jaguarforums.com/forum/xj40-xj81-25/ Both also have some very knowledgeable and helpful posters - as does xj40.com.
They're lovely cars. I have had mine (a paltry 3.2 litre Sovereign) for a huge length of time, but it never ceases to make me smile. I hope yours is kind to you!
You probably know this, but there are several forums which have quite a lot of expertise on the XJ40/XJ81. There is www.xj40.com which you have already joined, but also worth joining are the Jag-lovers forum https://forums.jag-lovers.com/c/xj40 and Jaguarforums.com https://www.jaguarforums.com/forum/xj40-xj81-25/ Both also have some very knowledgeable and helpful posters - as does xj40.com.
They're lovely cars. I have had mine (a paltry 3.2 litre Sovereign) for a huge length of time, but it never ceases to make me smile. I hope yours is kind to you!
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