Hi all.
I took the Jag out for a run this morning about 20 miles as the mot is booked for next week. This is the first runout this year so was really just to make sure all is ok. Anyway about 2 miles from home the engine cut out. I managed to coast into a lay-by but no start. Turns over fine not a hint of firing. Ah I thought as this happened last year on the way to a car show b bank temp sensor. All looked fine pulled the plug and refitted no go. Connected the plug terminals with a piece of wire still no go. Sat there for 10 minutes and had another fiddle with the sensor wire and it burst into life so drove home. Got home with no further problems. I thought it might be dodgy wiring at the sensor but I can’t get the engine to cut out idling in the garage while pulling and twisting the wires. If I pull the plug off the sensor it immediately stops. I replaced the sensor last year when this happened. Any ideas.

Rob.

 

Crank position sensor maybe?
Incredibly irritating when they start playing up, car runs fine and then just stops dead.
10 minutes later it trundles off quite happily.

 

Robbu, Steve has a very good point. Change them both!

 

Morning all. Thanks for the replies. The sensors as far as I know haven’t been replaced so will be factory fit. Happy to replace both however I’m still not convinced that the b bank temp sensor wiring or plug is good. I had a multi meter on it yesterday and get just under 5v on one terminal and 0.01v on the other and I couldn’t get this to falter despite vigorous wire twisting. I read somewhere that the plugs can breakdown inside and cause problems. Maybe mine is affected by heat?? If I replace can you guys point me in the right direction for a replacement plug.

Rob.

 

Rob,

Bosch 1 287 013 003 is the kit I have used for years.
Comes with the plug 2 terminals, 1 boot.

I have not needed for 20 odd years, so Google, ?bay, etc will be the go.

Same plug as the Injectors, ATS, Cruise solenoid, etc.

 

Cheers Grant.
Plenty on eBay or Amazon. I think I will replace this as a matter of course. What are your thoughts on the cps and my cutting out probs.? I assume that if it’s the cps then the 10 minute wait yesterday and last year was enough for it to perhaps cool off at bit and start working. Like I said earlier this is the second time this has happened first was late last year just before the car was put away for the winter. Cheers for all your help as always and that goes for the other guys as well. All very much appreciated.

Rob.

 

Rob,

The COS can go legs up for no reason at all. Our XJ40, X300 both did that in the driveway after a run. NO tart 5 minutes ater, oops.

I used teh old Opus remedy, COLD water sprayed on the sensor, satrted right up, damn.

They do operate in a very harsh environment when you thing of it, and a magnet. We all know magnets and heat are NOT a match in heaven.

The rear one is living easier, but plain old age is against you now.

Memory, HAHAHA.

One Marelli beast in our group got like yours years ago. When the front sensor was unplugged from the loom, down below the breather vent elbow, it was full of cruddy oily goo. Cleaned it out, WD40 prior to replugging, started right up and never failed again. The oil leak was fixed before someone asks.

 

Thanks Grant. Mine starts fine and then both cut outs have occurred about 20-45 minutes later. I suppose the cold water trick is the way to test when it cuts out. If it starts up after being cooled with water then we would definitely know it was at fault. Don’t really want to take it out again to test as I might not be so lucky with being able to pull off the road. One thing I have noticed ever since I have had the car is that occasionally it’s as if the engine momentarily cuts out then carries on as normal. I don’t know if this is a sign of a failing cps.

Rob.

 

On the AJ6 and AJ16, YES.

 

R obbo
Changing the two CPSs is an absolute MUST if they are the originals or more than 10 years old.

FWIW, I recently changed by coolant temp sensor and air temp sensor, and their plugs and renewed about 10 inches of wiring to them, and it made the engine start and run better. This is what I used:

Or these with pigtails will do:

The first option allows you to use silicone insulated wire though. I used those solder tubes to connect to the old loom, having cut back the crispy bits!

 

I had a similar problem last summer. Ran fine, then died. Let it cool for a bit and it fired up and then died again as the temperature rose. I traced it to the ignition amp, but my car is Lucas so you have different components.

 

I assume this will do the job?
https://www.britishparts.co.uk/class...ition-dbc12508
ROb.

 

Or this one from Manners.
https://www.jagspares.co.uk/product/...a%2a1%2a%2a%2a

Rob.

 

Just purchased 2 of the DBC12507 leads that SNG Barret sell from a chap on eBay for £80 the pair delivered on Wednesday. Not a bad deal that. Front looks easy to fit not sure on the rear though. Any tips on the fitting greatly received.
Rob.

 

If you change them both at the same time then that might fix the issue but you won't know which was one was at fault.
Change the front one first and if that fixes it then you can keep the other one as a spare.

 

Bad idea Steve. I say chnage both, as both will be iffy, even if one works. And you will be stranded, Robbo, at the worst possible moment.
Do not tempt the Gods!

 

Greg. Don’t worry I will appease the gods and change both. Any tips on changing them. I have read they need a certain air gap.
Rob.

 

Hi Robbo

The Gap wants to be as small as possible and no wider than 042 in order to Trigger the ECU and you may have to elongate the Holes on the Bracket a little bit to get that gap (with a small round file)

The Rear Sensor Monitors the Engine RPM for the ECU

The Front Sensor Triggers Injectors and the Spark and its almost always the Front one giving the problem

In the interests of Safety I wouldn't want to be doing the Rear one, unless the Car was up on a Garage Ramp, so it may well be worth giving your local Garage a drink for them to do this for you (while you watch) or preferably let you do it yourself

As for some strange reason some Shops tend to over tighten stuff like that and maybe also don't realize the importance of that Gap

 

Robbo, when I changed the rear one on mine I tied some string to the original before it was removed. This was then pulled through and used to pull the new one into place in reverse if that makes sense. Was a bit fiddly but doable. Credit to grant or Greg for that tip .

 

Morning guys. Thanks for all your replies. As on on holiday from work this week I will be getting the car MOTed today so if the sensors arrive I will hopefully tackle the job today or tomorrow. I have another annoying problem which I will start another post about. I bet you guys can’t wait 🤣🤣🤣

Rob.