Sudden engine failure...bad CPS?

[wizrod]

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

[J44EAG]

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

[wizrod]

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

[Brakebuster]

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

[wizrod]

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

[wizrod]

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

[cafcpete]

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

[steve_m]

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

[cafcpete]

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/