www.jec.org.uk

Good morning all,

My '95 4l manual XJS failed me yesterday evening...I was sitting idling at a junction (after a longish drive) when the engine just died. No warning. One moment it was running smoothly, the next...not. It turned over, but wouldn't fire up.

After pushing the car to safety, I ran a couple of checks (while waiting for a tow). I confirmed that the fuel pump was running and that there as no spark.

Reading round, I see that the crank position sensor is 'notorious' for suddenly failing and that when this happens, there is no spark and the injectors don't fire. Is this a likely culprit in this case?

I should say that until it koncked out, it had been running extremely smoothly, though I had noticed a very slight hesitation at around 3000rpm.

I look forward to reading your thoughts.

Merry Christmas

Paul

I`ve seen this several times on the AJ16 engine. One one occasion it was accompanied with pre-failure mis-fires. The CPS had failed in each case. Fortunately, with a new sensor, normal service is quickly actioned.

Only yesterday whilst traveling on the M25 near Clacket Lane Services, I saw a superb black X300 LWB on the hard shoulder with the AA in attendance. I`ll bet that breakdown was due to CPS failure!

Obviously a further electronic interrogation will confirm one way or the other. Hope you get it fixed shortly.

Mike K

Thanks!

I believe I can source one locally (if not cheaply!) and it looks to be a relatively easy job to swap the old one out for a replacement.

Hopefully normal service will be resumed in time for Christmas!

Cheers

Paul

genuine jag can still be bought for about £100, it will be a Lucas branded one

yours being a 95 will probably be the three' round ' pin ones, make sure you buy the right one, or the plug wont fit....

others can be bought on ebay and motor factors for around £40 , they work fine, but longevity not tested.....your choice

installing is a ten minute job , but prepare for skinned knuckles

one tripping point is the bracket, they are made from low grade alloy , and can break at the point where the sensor fits , be very careful

good luck

BB

So...a bit more info...I have also read that an indocator of a failed CPS is that the tacho needle doesn't move when you turn the engine over....

I have just tried that and the needle moves ... hovering between 6-800rpm or so...so maybe it is something else that has died...? 

Cheers

Paul

The car is back up and running!

I replaced the CPS and it fired up 1st time. It only took a while as I have been away over the holidays...

Anyway, many thanks for all your comments and suggestions.

Cheers

Paul

Now you have played with the CPS and bracket, and its working again, you might like to consider an improved version of the bracket.

I have one fitted to mine and the improvement is very noticeable.


http://www.exclusively-jaguar.co.uk/sal ... r-bracket/

Check it is suitable for your engine, but as stated (at the bottom) in the above article

The AJ16 version of this bracket, priced at £75.00 including postage, is a simple to fit modification which could soon pay for itself (£36/year saving assuming 3000 miles per annum, an improvement from 28 to 30mpg and fuel @£1.10p/litre).

The same revised bracket can also be fitted to late AJ6 engines, after engine number 161586.

Earlier 3.6L engines (after engine number 108834) and 3.2L/4.0L engines (up to engine number 161586) need a different revised design of bracket. As these brackets are produced in smaller quantities, the price is £90 including postage.

Fits all engines listed above, as fitted to XJ40, X300 and XJS

Where are you living that you can get fuel at £1.10 a litre?

LOL
That was cut and paste from the web site article from 2017, which I think came from calculations make in 2012 when Andy first designed the bracket.

I no longer see much fuel saving because I now use the extra performance far to much!

If you want a long read this was when Andy was first discussing the project.
https://www.jaguarforums.com/forum/xj-x ... nes-66536/