Link to Car: Jaguar XJS TWR - Album on Imgur
So I Just picked up my dream car on Friday, 1985 Jaguar XJS V12 with TWR package(includes spoiler, wheels, ground effects, painted bumpers, quad stainless exhaust and possibly engine mods have not dug that deep yet if anyone can tell me about it I would appreciate it!).

It has 123000 KMs on it or 77000 miles on it.
When I got the car it had been sitting for the past 3 years without an oil change and I cringed a bit. The owner said he only drove 1000 kilometers on it so he felt it did not need to be changed. First thing I did when I got it safetied was to change the oil. I have been looking pretty hard for one of these with a little body rust as possible and a good working engine. This one came with no signs of rust anywhere and the engine seems to be in good working order (made the 5 hour drive home without breaking a sweat).

So far everything works but the passenger window(not the switch I tried a different one any suggestions?), A/C compressor is toast(from service records and never replaced), and the radio antenna mast needs to be replaced(i know cheap and this car should not be in the same sentence but anything cheaper than the $200 Merlin Replacement?). Besides these little "niggles" the interior is great no rips or cracking in the leather, it has that distinct old Jag smell to it.

So far all I have had done is the oil change and I ordered some K&N Air filters to replace the stock(and likely original) paper ones. I noticed that occasionally on idle the car will stall and I have no clue what could be causing this (besides maybe the ignition wires are a bit loose?) and it is usually only when I start the car for the first time and this seems to be the biggest issue to me as I need to be able to daily this car. It only ever happens when the car is stationary and sometimes in park if you give it a small rev it will stall but wont on a higher rev.

 

Possibly a dead motor.

Or the glass might be binding in the felt tracks....which isn't unheard of. If this was the case you'd probably get some sense that the motor was *trying* to move the window, but can't. You heard something, or the interior lights would dim quite a bit as the motor strains.




I'd find a good used complete antenna...likely for much less than $200...just to get a good mast.



Any suspect wiring must be repaired....and you're likely to find quite a bit of suspect wiring, especially engine wiring, as you dig deeper into the car. That's just part of the deal with old V12s.



To clarify, do you mean the 'first time' you start the car each day, and then it's OK for the rest of the day? In other words, the engine stalls when cold and is OK after warming up a bit?

The 'could be' list is long and you might have a stack-up of conditions contributing to the symptom.

When started cold does the engine idle at 1200-1500 rpm for a minute or two and then drop down? It should. If it doesn't the Aux Air Valve (AAV) is probably dead. Quite common.

If the stalling occurs when warm then I'd begin being by cleaning the throttle bores, setting the throttle blades to the proper .002" gap, and synchronizing the linkages. Can't hurt, might help, has to be eliminated as a possible cause.


Which might also suggest a faulty TPS-throttle position sensor.

But, again, if it happens only on a cold engine, a skewed coolant temp sensor (CTS) might be to blame. The CTS plays a major role in 'cold fueling. It can be checked with an ohm meter if you have one.

Cheers
DD

 

Wow thanks for this I will check this out for sure. To clarify it is on a cold start only (although it did happen once embarassingly when I first bought the car taking it through a touchless car wash just to get the dust off). I did notice that on cold start the car does NOT rev up to 1200-1500. In fact when I first purchased the car as the noobie I am I was a bit concerned how I could barely hear the engine after startup. It immediately idles at what I assume to be around 500 rpm.

 

Yeah, most likely an inoperative AAV.

Many repair/rebuild the AAV. Lots of archived info. New ones are costly.

However....

Others have lived with an inoperative AAV for years. Just tweak the warm idle speed up to about 700 or so. This will probably be enough to keep the engine running when cold. I went for years this way. No problems unless/until the ambient temp was sub-freezing...which mandated a bit of help from the driver by way of keeping the throttle open a wee bit for 30 seconds or so by using the throttle pedal.

Cheers
DD

 

Nice car..loving the colour and the shine on that thing.

The body kit is probably best described as TWR inspired, as it differs TWR kit. The rear bumper shape and spolier aren't the same as a TWR or XJR-S design.

Regards
David

 

Nice car

that could well be a ' Lynx ' body kit, as in the ' Lynx Eventer ' company , as they did convert Coupes as well

either way , V-nice

BB

 

claytronno,

Nice-looking car and good colour! Like others have said, I'd say it's definitely not a TWR kit. In fact, it's difficult to identify whose bodykit it is. I can tell you what I think it isn't. I don't think it's from TWR, Lynx, Arden, Lister, Koenig or Hyper. The bits that are unusual are the sharp front ends on the spoiler and the part of the front spoiler to house the front foglamps. I can't recall seeing a kit with those features before.

However, there were other small companies making their own kits for XJS so perhaps it's from one of those companies? A lot of those companies have disapperared so perhaps it was done in period in North America?

Have you got any engine or interior mods on the car?

Cheers

Paul

 

Picked up a used AAV off a car with 49k miles for $20 cleaned it up and installed it now my cold idle is perfect! Thank you so much for your help. Antenna is now replaced as well, and I replaced the battery, and after my mechanic diagnosing the window motor as broken and taking it apart it magically started working a couple days ago(i presume it has to do with the battery somehow).The only problem I have now is my cold start itself is very weak. I find it has to crank for so long to get going and I hear it just starting a little bit. If I give it a little rev just when I hear the engine kind of starting it does it's normal cold start idle as it should and I can drive away as if nothing happened. I read a couple threads but I am trying to think of what would be the most likely culprit now. Any suggestions?

 

Great looking car!

I would change the coolant temp sensor anyway. They are cheap and easy to source.

I find with starting or running issues its a good idea to make a video of the issue, then share the video (put it on youtube, add a link in your post)

Your idea of a weak cold start could be "perfecty acceptable" to others who have had V12s for a while. They do certainly take a while to crank and fire under certain conditions. Or it could help others understand exactly what the issue is. A picture is worth a thousand words, so I guess a video is millions of words :-)

Read these forums thoroughly........ download Kirby Palms experience in a book (its free) A great resource for the XJ-S owner...... also get yourself a good repair manual. Jaguars own ROM (Repair operations manual) is actually pretty good.


Jaguar XJS Shop Manual Repair Book Service V12 XJ s 5 3 6 0 Workshop Operations | eBay


Dont worry about the price...... the first time you use it to fix something yourself it will pay for itself.


Talking of fixing things, whats your plan for working on the car? Do it yourself or use a mechanic? The second option can get very expensvie, especially if your mechanic is not familiar with these cars. And thats another point..... if you are going to use a mechanic, make sure he is well versed on Jaguars and the XJS in particular. I know great mechanics who end up tied in knots with an XJ-S. Thats no disrespect to them in any way...... its a simple case of experience. You work on these things for a long time, you get to know their quirks. If you don't, its easy to make a small problem into a big problem.

You have a Borg (if you're a Star Trek fan) collective intelligence on this board which will be a big help to you. These cars tend to fail in similar ways for many of us, so what seems alien to you may have already happened to a few of us and we can save you the pain of trying to work it out

Welcome to the very unique experience of XJ-S ownership.

 

My experience is that a cold V12 needs several spins of the starter. Maybe 4-6 spins.

Try this:

Turn key "on", you should hear the fuel pump run for two seconds to pressurize the fuel rail. Now press the throttle to the floor once. You're a actually opening the injectors to give a spurt of raw fuel into the cylinders. Then turn key to "start".

Any change?

In my experience this will allow a cold engine to start in 2 spins of the starter


Cheers
DD

 

I will give this a try this morning, its hard to test now as the weather has just gone 30+ C in Toronto but ill try it todaY. In the current weather some times it starts on the first spin so maybe I am just giving up too early when it cranks 4-5x before starting

 

If everything is top notch, the car will fire just about immediately, certainly it will not need several churns. If the fuel pressure is iffy, or the B bank regulator is going home, it can take several goes on the ignition, without the starter being tried, to prime the injector rail, as the ECU 2 seconds is not enough to do it. So you could try Doug's priming advice a few times in succession, before trying the starter. I have just renewed my B bank FPR and the difference is noticeable
If that test makes no difference, then if the dizzy cap, rotor, HT leads and plugs are, any of them, not right on it, that will cause it to churn before starting, too. By and large, HE engines start from cold really easily, it is hot starting that most people complain about. After that, if that does not help, then engine earths are a known cause as The Great XJS Prophet (AKA the Wizard of Oz) has taught his many disciples.
Greg