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Daimler Double Six misfire - ECU issue? Where do I refurb?
Good afternoon, all,
First of all I tried deleting my first post about the Double Six ECU but I can’t find the option - if a mod reads this please could you delete for me? Thank you.
I have a 1997 Daimler Double Six (Japanese import). The car is lovely and, when it behaves, is a car like no other I’ve experienced. I’ll attempt to water down my issue(s):
At one stage one of the head bolts corroded (odd right?) and coolant started emanating from there. It ended up needing a top end rebuild with new head gaskets, plus new timing chains yadda yadda. I’ve also had a new rad as that was leaking.
It now produces a misfire on one of the cylinders (#7 if I remember correctly). This is only noticeable at idle and when pulling up to traffic lights. Otherwise it drives and performs as it should. No warning lights on the dash but it does produce a code for a misfire and, consequently, a multiple misfire. I’m informed by the Jag specialist that the ECU apparently knocks out the opposite cylinder should a misfire occur in an effort to “balance out” the issue.
I have had new spark plugs, new coil packs and new HT leads fitted and have had the injectors cleaned. I have also had the engine terra cleaned. The specialist feels he’s exhausted all mechanical options regarding the misfire. We have also eliminated the possibility of fuel being dumped in the cats as we ran them up to temp and got temp readings from them and they are well within normal parameters. He now suspects that the engine management ECU might not be playing ball and there might be some water damage (I’ve heard this is common?) or perhaps some parts on the circuit board which could do with replacing.
Any thoughts? If I get an ECU refurb where is best to get this done? I understand the Japanese variants do have specific ECUs for the emissions (there is an exhaust temp sensor for example). The part number on my ECU is: LNA1410NB/004 and it runs the Nippon Denso EM system.
Any advice would be enormously appreciated. I’ve thrown a lot of money at the car and whilst it’s a dream (it’s actually one of the cars in my wedding fleet) it would be fantastic if I could iron this last issue out!
Tricky this given it is a Japan market car. You might want to pester Denso to see if they have any refurb people they recommend? Might even be worth trying to get hold of someone technical at Jaguar Heritage too. Otherwise it's email and phone around ecu test and repair businesses. I haven't had to go down this path yet (thank goodness!).
Where did you find a radiator? That's one of the things I stress about my car...
There was some recent discussion on I believe the same " cylinder pairs " misfire on the V - 12 with internal ECU component pics that would have to rattle around on this forum to find
There was a chart showing the switching point for the earlier Lucas / Marelli ECU and the Denso ECU
The ECU in my car suddenly failed last year. After weeks of component checks and replacements, I was lucky to find a used ECU not too far away. That was the cure. I believe the old ECU had a problem with the O2 sensor inputs, and would cause a serious rough-running problem after it heated up a bit.
I have not put any effort into finding a rebuilder so far, although it would be desirable to have a spare. Due to the extreme rarity of this car, it might be difficult to find one able to.
I've not ever heard of an engine ECU cutting out an opposite cylinder to balance out a misfire. Sounds silly to me, but maybe it is a thing.
In the meantime, if not already done, you must remove the ECU and check for water damage on the wires, plugs, pins or internally. If all seems good then you could swap coil packs A/B, and then ignition modules A/B to see if the misfire code follows the component.
There was some recent discussion on I believe the same " cylinder pairs " misfire on the V - 12 with internal ECU component pics that would have to rattle around on this forum to find
There was a chart showing the switching point for the earlier Lucas / Marelli ECU and the Denso ECU
The ECU in my car suddenly failed last year. After weeks of component checks and replacements, I was lucky to find a used ECU not too far away. That was the cure. I believe the old ECU had a problem with the O2 sensor inputs, and would cause a serious rough-running problem after it heated up a bit.
I have not put any effort into finding a rebuilder so far, although it would be desirable to have a spare. Due to the extreme rarity of this car, it might be difficult to find one able to.
I've not ever heard of an engine ECU cutting out an opposite cylinder to balance out a misfire. Sounds silly to me, but maybe it is a thing.
In the meantime, if not already done, you must remove the ECU and check for water damage on the wires, plugs, pins or internally. If all seems good then you could swap coil packs A/B, and then ignition modules A/B to see if the misfire code follows the component.
Some great insight there, thank you. Yes I think I’m going to take it to someone who can refurb. I’ve not yet found a second hand unit.
In sourcing a V - 12 ECU part # / donor car there was some recent discussion on the last years of V - 12 production ECU internal components / programing / EPROM / mapping change to satisfy I believe California regulators
Mark Oliver has a California car that the ECU part # can be obtained as an example thay may or may not be the latest example of the change
Yours being a British example and area regulations may not be affected but gives a picture of world wide part ( ECU ) variations in your search
Daimler Double Six misfire - ECU issue? Where do I refurb?
