Engine keeps cutting out

[John579]

Hi, My 1996 coupe engine keeps cutting out - a little background - this started 4 weeks ago, when having problems with gearbox fault showing on dash board and self clearing after a few switch off/on’s…. The specialist Jag garage in Swindon found the major plug/socket at the rear of the engine, connecting the Transmission Control Uni with the ECU had some moisture present and cleaned/dried = all well…..
Until I collected and during the drive home, it missed a beat and displayed Engine Fault, but cleared by switching off/on….
Then a week later visiting Swindon for a breakfast meet up with friends - a major misfire, resulting in limping into a pub car car park with what felt like 2 cylinders… and major dark brown smoke…. after an hour the AA man arrived and the car started and run almost normal…. He followed us the 10mins to the garage…
Jump 3 weeks later and the cars still in the garage - now running great (replaced some coil packs) BUT now randomly just stops….. garage thinks it could be the ECU….
Any ideas?
If it is the ECU - sounds a big/expensive job?

[Astromorg]

This sounds remarkably similar to this problem

viewtopic.php?f=65&p=88253#p88253

that was solved just a week ago! That would be a remarkably convenient coincidence!

[John579]

Thank you Astromorg, just passed this onto the garage, but unfortunately they have replaced each and every relay in the car…. Did also suggest the crankshaft position sensor as a contender - they have it on the list along with the throttle body and knock sensors….
Will update with a solution if we get there….

[Astromorg]

Those suggestions are certainly possibles, though some fault codes should be coming up I would have thought. Has a diagnostic scan not shown any?
If the ECU does prove suspect, there are repair services available.

When the engine stops, how do other systems behave? Do the lights still light, cabin blowers still blow. I'm thinking of loose battery and fuse connections (inside the box), ground connections and also the connections to the high power protection module, next to the battery that have been known for getting loose.

[John579]

Latest news update - garage called today, everything tried and only one thing left - the ECU - However the problem is it’s such an early car.... within the first 1000 built..... and can’t find a replacement.
Question = anyone know if anybody repairs these?
Otherwise it’s going to be sold for spares.

[andypryce]

American site, but worth a try?
https://www.ebay.co.uk/itm/281938390385

[Astromorg]

I've no personal experience of either of these two outfits, but both have excellent reputations

https://www.bluehawkelectronics.co.uk/

https://www.avilec.co.uk/

If you're brave, you might like to consider opening up the ECU and physically checking it for obvious component failures. Early modules are known to suffer from faulty electrolytic capacitors that show obvious signs of leakage. They can be individually removed/renewed if you're handy with a soldering iron. Even if you don't try a repair, there maybe a visual confirmation of a problem

[andypryce]

Not sure where you live, but may also be worth seeking advice from David Marks on this before scrapping the car.

[John579]

Hi, update on engine cutting out, it’s so random that it must be the ECU, unfortunately due to it being a very early model this hasn’t worked out, so will sell for spares....
On the plus side, I am currently purchasing a XK8 2003 year but registered in 2004 - Happy Days....
Thank you for all your support.
Regards
John

[andypryce]

Yup, sometimes you have to admit defeat.