Dear Jag lovers, I have an issue with the ECU (model LNA1410NA005) of my Daimler Double 6 (year of production 1995) and need advice to resolve this complex situation as this spare part has been discontinued by Jaguar.

The engine is stopping when hot after operating properly for 15 min to 1hour. I had the car diagnosed by a professional who confirmed 100% that the issue comes from my ECU LNA1410NA005, which needs to be replaced or fixed.

I have been unable so far to find either a replacement or someone able to repair my ECU.

Did anyone of you face a similar issue? Could you recommend a supplier for me to buy the ECU or to repair it?

Thank you in advance for your support!

 

PS: the engine stops mostly when the car is immobilized or moving very slowly. I recently drove 600km without interruption and the engine worked perfectly. The issue of engine stopping happens randomly and the engine starts nicely when the car is cold usually.

 

Welcome to the forums Antoine,

That seems an unusual combination of circumstances. I could agree with diagnosing an ECU fault if the vehicle will not start BUT as it starts and runs then only stops when hot it suggests the problem is temperature sensing related.

However, I do not know enough about the V12 installation in the DD6 and hopefully other members with experience of this will jump in.

I've checked Jaguar Classic parts website and the LNA1410NA005 is unavailable from Jaguar. It will inevitably be a rare ECU from the limited production of the model and a repair is likely to be your only option.

Graham

 

OOPS

My involvement with the 6ltr is ONE only, and that was look but dont touch.

Only 7 or less in our whole country, including XJS variants.

Like GGG mentioned temp related, and I agree. I would be replacing the Engine CTS (Coolant Temp Sensor), On all the earlier V12 engines, this is a PRIME sensor for the ECU. Example: Running V12, unplug the CTS = Dead V12, it was that simple.
ALSO, these sensor can and do, go "flaky", and give odd signals to the ECU, which cannot decipher them, so shuts down the system.

The fact you drove 600kms, NO issues, meaning the engine temp would have been at a very constant degree, which I reckon, the sensor could handle. Stop start driving, engine temp rises, falls, rises again, the sensor cannot keep up, shuts down.

Your engine has Crank Angle Sensor/s. They only have a limited life, and heat is not their friend. Again, the earlier Marelli V12, with this issue is usually Sensor related after the CTS.

ECU failure on any Jaguar is RARE, and I have never encounted one.

The testing would give ECU fault, but that could be due to Sensor failure.

 

With any luck at all, this can be fixed, so have faith! A few questions:
Is the car the X300 body-shape please,

or the XJ 40?

Has the car got the Marelli ignition system or the Nippon Denso system? Please post a photo of the engine bay, engine cover off, if you are not sure.
As the engine acts up when it is hot, I concur that the problem is sensor-related, not ECU caused. A faulty temp sensor could be reflected in an ECU fault-reading. Depending upon the ignition system, I may know people who can repair the ECU if it does prove faulty.
Can your expert specify for us what fault he found in the ECU?
The coolant temperature sensor is on the LHS of the engine (looking forward) on the water manifold which leads to the top hose to the radiator. no. 18 in this diagram:
https://parts.jaguarlandroverclassic.../brand/jaguar/
I would certainly change that anyway, as they are notorious failure points.

 

I have a used one from a '96, same part number but suffix 002 not 005
I don't know if it works, the parts car is dead.
I have a '95 that is working well, I could put it in that car and try it.
I'm a long way off, but if you are stuck maybe I can help.
Good luck,
Rob

 

It would be the X300, and it has the Nippondenso system, with Ford coilpacks. As a though it could be possible that you have failing coilpacks, as they are in the V of the engine and get hot. The ECU is in the car, so much less exposed to heat.

I suspect the difference in the ECU numbers between yours and Roberts is that North American spec cars did not have imobolization, the rest of the world did.

Another thought might be to contact XJREngineer on the X300 forum. He was the man at Jaguar who designed the X300's igntion system for the XJR and XJ6, he can reprogram these ECU's. He might have the ability to function test it for you as well. He's in the UK.

Greg, if I'm to nitpick, the first photo you posted is an X308, a V8 car that came after the X305 (V12) or X300 (6 cylinder). Very similar bodies though.

 

Have a look at page 65 to 68 of this PDF. It will list all the comments and some of their normal values
http://www.jagrepair.com/images/Auto.../jagxj1995.pdf

I would go about this in the following way with since I dont have access to the proper pecus diag equipment

Hook up a test lamp to the fuel pump +12 lead so you can monitor it inside the cabin.

1. You need to monitor how long the fuel pump runs during / when a cut out occurs.
if the fuel pump cuts out abruptly when the stalling occurs you have an ECM power supply issue or some other fault with the fuel pump circuit or internal/external power for the ECM.

If the engine stalls and the fuel pump continues to run for 2 seconds or more, you have a input signal supply problem to the ECM, check / clean the engine speed sensor and related wiring at the flywheel, crank positions sensor at the balancer and the cam position sensor at the cam cover.


2. You want to look at your tachometer when the stalling happens
If it abruptly drops to zero you mostly likely have a signal supply problem from one of the 3 sensors listed above

If it drops slowly and seems to follow the engine speed exactly as it stalls you most likely have a fuel supply problem, related to fuel pump, relays or injector output transistors in the ECM

The first thing I would do is check the the three sensors, crank, engine speed and cam. The engine speed sensor on the bell housing needs to have the exact gap and the wire is routed near the exhaust manifold so it has to be checked. It hangs low too and will pickup any metal dust it can. I have fixed random stalling V12's simply by cleaning this sensor with a quick wipe with a blue shop towel. A zero dollar, fast repair.

It may be helpful to understand how coil on plug cam synch ignitions work. You have to know is that the ECM waits for a full cam rotation to find TDC then it starts counting and firing the coils soon after. If the ECM looses count for some reason, like bad or unclear sensor data it will stop ignitions pulses until it a reliable re-synch can be established. At low RPM (idle) this can cause a stall. On the highway at speed the engine over run gives the ECM enough time to resynch. In this case the tachometer should show a dip during the resynch process but it may be hard to notice while driving.

 

the V12 can suffer from ' fuel vapour lock ' issues, where the fuel turns to vapour in the fuel lines around the engine,

this starves the engine of fuel and causes issues like your experiencing,

just another issue to be aware of

BB

 

Check the original thread on the XJS forum, Antoine, as ICS America has posted some useful points on there.

 

I've copied the icsamerica and Brake buster posts from XJS forum as the OP Antoine KIN is probably not aware I posted a request for help from V12 owners there.

Graham

 

Not sure how sensitive to voltage the X350 is, but I would check the battery is in very good condition. It may have enough juice to get the car started, but struggles to keep it running until the alternator has fully charged up the battery.

 

I think you mean X305 (V12 version of X300 from 1995-1997MY) not X350 (aluminium bodied saloon from 2003, I think)