Mobeck Tekniske has developed a “plug & play” Bolt-on EFI kit for the Jaguar V12.

After one and a half year of designing and testing it is finally ready. The problem solver for all Jaguar V12 engines.  If you have any of the phenomenons mentioned below on your 1975 to 1988 V12 you shold keep reading.

Do your V12 have:

  • High fuel consumption
  • Low idle when it should be high
  • High idle when it should be low
  • Fouling at Idle
  • Lacking power
  • Variable reliability
  • A lot of smoke behind at startup and idle

Have you tryed this:

  • Overhauled all injectors
  • bought a new ignition amplifier
  • Boght any new vacum solenoids
  • Fully understood the vacuum system
  • Exchanged the thermoswitch at the rear of the right cylinderhead
  • Bougth a new Idle valve 
  • Syncronised the throttles
  • And so on…

Well, if you haven’t started on it, you will learn it, and if you have you are probably nodding approvingly.

So, after many years of dealing with Jaguars and it’s great V12 engine I have seen the need of a complete problem-fix kit.

Throw away this

If you start in one end and try to completely understand the vacuum systems for the ignition advance. Then hunt down the solenoids and buy them, and then find a coulpe of injectors fail, and the amplifier is broken and so on. You normally end up spending a good driving season and lots of money. If you are good and manage to fix it you still end up with 40 year old technology.

So here are a few pictures of the new Bolt on kit

Design of the ECU casing
New engine harness
ECU with fuses and relay
Ethanol aproved fuel lines
New injectors with mounting brackets
Injectors in place
Remove old IAC valve, mount blanking plate and new ECU contolled active valve

You can make a V12 run in a day, but to make it run as intended from the factory takes some effort. And I dont want (preferably not) to take my customers money to make it as a mint 40 year old system anymore . The most recognitionable signs of the need of this kit is, high fuel consumption, wrong idle level and smoke at startup. So I have developed this system that bolts on and looks very originlal with harness and everything, and if makes the V12 run correct.

The kit is delivered with these parts:

  • New Air and Coolant temp sensor
  • New terminated harness with connectors, fuses and main relay
  • 12 new Bosch injectors with 10 Degree spary cone
  • Ethanol aproved rubber hoses with mounting clips
  • Injetor brackets, laser cut stainless steel
  • new electronic controlled idle valve
  • Blanking plate for the old Idle air valve
  • Coil driver with heatsink
  • Coil
  • Control wires for Fuel relay and fan relay
  • New MAP sensor
  • New modern ECU delivered with a map for a std engine
  • Optional wideband Lambda sensor.
  • Installation manual.

The great thing about this kit is that you dont need to install and calibrate a new crank trigger wheel with sensors and such, not multippel coils that look like 2020 and beyond. You dont need to g to a dyno session and make your own map. The idle and cold start system is tested from minus 15 degree celcius and up to +30 degree with a stabil idle level both in Neutral and drive. I have implemented fuel cut systems and it leans out or richens op at the correct driving modes fr better fuel effichensy.

What you need to do to install it is:

  • Before you take off anything you should check the Ignition advance acordingly to the innstallation manual. It should be std spec.
  • Remove old fuelrail and take off all injectors and old rubber hoses
  • Remove the old Idle air valve at the rear of the left head and mont the supplied blanking plate.
  • Remove the complete original injector harness.
  • Remove the ignition amplifier.
  • Remove all engine related vacuum lines. Ecept the one to the automatic transmission, brake booster and climate system.
  • Remove the original ecu in the trunk. Blank the rubber hose.
  • Install the new idle valve with the supplied hoses.
  • Adjust the throttles and tps accordingly to the installation manual.
  • Install the new injectors to the fuel rail with the hoses and clips supplied.
  • Place the new harness nicely into the engine and the ECU plug towards the Brake booster
  • Mount the fuelrail with its new injectos to the manifold with the new injector mounts supplied.
  • Mount the new air and water sensor where the old ones are at the left front of the engine.
  • Plug the harness into the distributor, idle valve, all injectors, tps sensor, coil, tacho wire, ign wire and temp sensors with the marked and terminated plugs on the harness.
  • connect the harness wire marked +12v to the battery and – engine ground to a screw on the inlet manifold.
  • Mount the new ECU on the supplied bracket that fits on the brakebooster and plug in the ECU harness connector.
  • Install the fuel pump wires on the harness to the fuel relay as describedin the installation manual.
  • Turn ignition on and check for fuel leaks when fuel pump stars for 5 sec.
  • Start up
  • Your idle should be 750-800 rpm when hot, 1100-1200 when cold.

The system has been tested for a long period both on the dyno, long trips and daily use in different conditions. the most difficoult is to calibrate the cold start systems and idle control. But Now I feel it is perfect and ready for most needs.

Dyno work with the new V12 EFI

The HP and Torque has been raised a bit and the testcar witch is a 1985 XJ12 with 100 000 km on the clock delivers 330 HP and 439 Nm on the engine with the popular Sport intake you find in the Jaguar Sport shop.
This made the car do 0-100Km/h in 6.1 sec and it has a fuel onsumption of 1.25 litres pr 10 km at variable contry road.

Find this kit with its options in the jaguar Sport shop here:
Email me if you have any questions about this please.

Best regards
Ole Martin Mobeck

    • Well, This exact kit you are looking at is not because it uses the P-Digital Lucas distributor. And its pre-programmed to the 5.3 HE.

      The 6 litre already has a pretty good system, (exept it still has that Idle air valve with the old technology).
      But since I have had many requests about doing a system for the 6 litre I am working on one now.
      It will include a new triggerwheel to mount behind the front damper where the original triggerwheel is.
      And two new coilpacks with total of 12 coils.
      But i dont know if I can make it pre-programmed as I need a car here to do it. I spend a lot of time to make the map as it is not only done on the dyno. I has to check and test the cold start systems on all temp’s from cold to hot, both air temp and egnine temp.

      But just follow this place and you will see whenthe new stuff is coming out.
      Also, by sending me an email at I can do custom systems for you.

      The system you see for sale here is for a std 5.3HE with P-Digital.

      Best regards
      Ole Mobeck

  1. Fantastic piece of work, Ole. Has the potential to add decades to the life of a classic engine. I suspect at the (quite reasonable, for the product) price point it may only appeal to the top end of town (many of the V12 cars would be worth less than the EFI!). I appreciate that it’s possibly not viable for you, but I think there might be quite a lot of interest in the replacement AAV: have you considered a ‘simple’ cut down controller that handles the cold start and hot idle only?

    • Hi Mathias Yes I understand your wish and comment, and many others also ask for spesific parts of this system to fix their problem. But After many years of trouble shooting on V12’s I have learned that the whole ignition, idle and fuel system often has several problems at the same time. When someone as if I can make their V12 run I can say, yes, it takes me 4 hours to make any V12 run. But it doesnt run nice, and then you start fixing the small things, like AAV valve, Termoswitch at the right rear, vacuum lines, some solenoids, maybe the map sensor dont sense, and then after all those things you end up cleaning and testing all those injectors, and change hoses on them, and then two are not closing, an maybe one dot open correctly, and you have to buy 3 injectors. And thy are supposed to match the other 9 old ones… And then you ended up spending 2-3 weeks chasing old parts, writing hours and end up with a 40 year old system.

      The thing is that Jaguar has been quite clever to make an ignition map on this cars that handles idle, warmup and fuel economy, and they did it with solenoids, switches, vacuumlines, thermostats and carefully adjustemnts. If you miss outy on one thing you spoil both idle and fuel consumption quality.
      So to make an standalone unit for Idle air you need to modify the ignition map witch is controlled by solenoids and, timers and temp switches, without changing the drive map. I then need to make something to controll the drive ignition map to make it as fuel effichent as it is supposed to be. I have to take avay some of the temp sensors, and solenoids but leave some in. This is not so easy, and you still end up discovering that you need to buy a couple of injectors and change the fuel lines.

      In my ECY I use both idle air and also Ignition advance wery active to make an stable idle. Both ign map and fuel map has an carefully PID controlled function. If I only used an Idle air valve I am afraid I would not be able to make an nice Idle at all temperatures. And I know my customers all over the world expect the idle to be 750 rpm, no matter what. I cannot make a idle control that is wery high at cold start for a car in Florida and almost stalls a car in northern Sweeden. And to do this I have to have full control of the whole system as the temperature rises. So.. A long answer, and not what you wanted to hear.

  2. Awesome work Ole, these charts look very promising too.

    I have a ‘83 HE which has most of AJ6’s aftermarket enhancements (larger throttle body, tuned inlet pipes, less restrictive air filter, bigger air inlets, wide bore exhaust all through and their enhanced ECU of course). Would your drop in system be compatible with that? Should it be beneficial to remap your ECU for this setup?


    • Hi Frank
      Great, yes, if you choose the EFI kit with active closed loop O2 sensor option it will absolutley adjust to the mondifications you mention. I would not need to remap it, it will aim for the optimum fuel target by itself.

  3. Hi Ole fantastic work you have done.
    Have you thought of doing a AJ6 EFI I have a 3.6 Arden xjsc with the old ecu and no trigger wheel at front.
    It’s a half v12 system if I understand it right


    • The AJ6 is not in my plans right now as I am working on the last touch of a system for the XK6 witch has more problems running nice than the AJ6.
      But I can allways make a custom sustem, but I have no AJ6 engine here to match up the heaness and calibrate the trigger system with.

  4. Hi I have a 1976 Pre HE V12 XJ-S. unfortunately I have the Borg Warner auto transmission.
    Will this kit work and what sort of performance and economy improvements could I expect? Thanks

    • I have not finished the Pre HE yet as the car is at the paint shop.
      It will need a slightly different setup regarding distributor modifications and some changes on the ignition map in general.
      But otherwise it will look the same. The performance on a Pre HE will be very similar and I expect 35 hp up like on the HE but the fuel consumption I dont know as your engine has much less compression and is not aimed towards fuel economy.
      But for the Pre HE I am working on a cam setup and also cnc ported headfs will be out soon.
      The auto trans is no problem, my white test car has the original 3 speed and does 0-100kmh 2 sec faster than before.

  5. What can you say about the Lambda sensor? Is this recommended to get optimum results of the installation?Where will it have to be installed?
    How can you check the original ignition advance to be standard spec?

    • Olav, yes the kit with Lambda is better, the one without Lambda has been enritchened 3-4% to avoid lean spots, but it will not adapt to other future modifications as the kit with Lambda will. It also constantly adjust to height above sealevel and weather changes.
      You drill a hole in the exhaust pipe just behind where the two downpipes meet and weld on a supplied ring with threads for the sensor. MIG weld is fine.
      Toe check the ignition you take off the vacum line to the distributor and block the end of the hose. Idle a t 750rpm and use a ignition strobe lamp under the front pulley to see if the pointer hits exactly 0 (zero) degrees. If it doesnt you adjust it with the small screww on the outside of the distributor.
      I can help and explain over the phone when you are there. Also if you have someone to help you and rev up a bit, you should see the pointer go all the way up to 18 degrees with the timing lamp. If not you should lubricate your rotor shaft in the distributor. Its quite easy and should be done anyway.

  6. I recently purchased a running 1989 XJS12. I just started taking it apart to go through everything to bring it back to like new/reliable. However, I like the idea of updated the engine management system. However, I would like to do away with the distributor as well. Coil packs or coil on plug would be great? I have a full machine shop so making mounts for sensors would be easy. Is this something that might interest you? I’m doing research to see if anyone has a solution. BTW my current ignition is marelli.

    • Hi Eddy I have made several systems for the Marelli cars now, with double sixpack coils, and you use the original cranksensor but install my tigger wheel on the original pulley. You must remove the distributor to make room for the coils witch is delivered with mounting brackets. You can make a plug for the distributor hole. Take a look here

  7. Ole, I’m thinking of getting one of your systems for my 1986 xjs HE , can’t wait to eliminate all of the old unreliable sensors and valves with meters of rubber tubing flopping around everywhere!
    Does the system use the standard distributor without modification?
    How does it sense the crank position?
    Can the system be integrated into/provide data to a CANBus system…I want to upgrade my auto gearbox but i don’t have a CANBus as yet and i understand that an input is required via the CANBus to the more modern multi gear auto boxes

    • Hi Peter
      Your distributor needs to be in good working condition, with lubricated upper shaft and weight working the full range. Then you can disconnect the vacum hoses and throw them avay, remember to plug the holes in the manifold, and dont remove the hoses to your auomatic transmission and AC control unit.
      I take the signal from the distibutor and do some clever stuff to it, from this I am able to do all witch is needed to make a 3d ignition map that also talk to the fuel map and idle control. The ecu has a can bus yes, but I have never controlled an auto box with it..? dont know how you can do that, maybe you need an transmission controller in between?

  8. Ole,
    From what I understand the gearbox needs information about throttle position, inlet vacuum, and rpm in order to change into/out of any particular gear, especially boxes with a proper lockup ability.
    All these parameters give the box an idea of the power going through the box or what is needed to achieve the throttle request., if all that makes sense?!?

    • Yes shure, I have earlyer worked on the GM 4l80 e transmission with compushift in a Jaguar, nice setup. And if your transmission controller can take a Can bus signal it should be fine as all that is available form the ecu

  9. will like to know the price of the kit and availability im in california
    will it work without any catalytic converters no smog, ??
    and a 4 speed manual transmission??
    installing v12 xjs engine in a 32 ford want to run the fuel injection
    gabe 7146049814

    • Hi Gabe

      The basic kit price is 37600 NOK witch is around USD 4450.- It will work nicely with or without catalytic converters, and please no smog pumps and stuff as it makes the o2 reading faulty if you choose that option. Manual gearbox no problem, several customers have that with their kit. I advice to have the o2 sensor upgrade at aprox 150 usd and I can also do a distributor delete kit with waste spark system and two 6er coils like this one waste spark kit

  10. Hello,
    What kind of ECU are you using? Motec? Haltech? Rusefi? Speeduino?
    i was wondering about that, if i want to modify the tune a bit…


    • Hi Bill, There is a modern well known ecu in there, witch have all kind of modern functions like canbus, bluetooth and many more options than what i include in the std bolt on kit.
      You have full access to making your own map.
      I just have not mentioned the brand in my advert as it only makes a lot of discussions. But I can tell you it is something much better than Megasquirt or Tec3, tuning software is the most modern and available to download.
      I tell you if you order. Its one of the biggest and most modern ecu’s in there.
      But some years ago I told what it was and I learned the British don’t want ECUmaster, the German’s don’t want DTA Fast, the Australian don’t want Maxxecu, the Swedes don’t want KMS and so on… so I just made an Jaguar casing for it and now everybody is happy. 🙂
      Well the casing is actually quite handy as I have included the main relay and fuses for ecu, injectors and coil in the cover, so everything is self contained. No need for external relays and fuses, just connect +12v on battery, ground on engine block, the original lead going with 12v to the coil connects to a wire I have marked IGN. and then the whole thing works.

    • Well, that is a matter of taste, but in all Jaguar workshop manuals it says 750 rpm and later V12 is 800 +-50. The good thing is that with this kit the idle is programmable, so I set it to be 1200 on cold start then it ramps down to 750 rpm as the water temp goes up. Its the ECU controlled Idle valve included in the kit that controls the amount of idle air it gets. And if you put it in drive so the rpm drops the idle air valve opens more to get a steady 750 again, just like a modern car.

  11. Ole,
    At the moment I have two fuel pumps, one as back up, that supply the HE unit.
    Is your system sensitive to fuel pressures?
    Does the software need anything special in the way,of hardware to enable correct tuning?
    Does the lambda sensor screw into the exhaust pipe, if so what is the thread size, I intend to tig a new mounting boss

    • Peter
      The preprogrammed system for distributor engines uses the original fuel pressure regulators as they are withiout the vacum compensation. This is just to eliminate all possible errors from faulty vacum and such.
      But if you buy the distributor less system (wastespark with 6 dualcoils) with a open map you can make your own map and do whatever you want with the fuel pressure. You can also over write my preprogrammed map on the distributor system but then you loose my map.
      The Lambda sensor needs a weld bung with m18x1.5 threads, standard thing. And it should be welded into the downpipe where the two pipes join, at the hottest spot.

  12. Hi, I currently own an 87 XJS HE , could you advise the current price along with shipping to Sydney Australia. in US dollars and your preferred method of payment. This looks a very good set up. Cheers Grant.

  13. Hello,
    I am Thomas from the Republic of Northern Macedonia
    and I am interested in whether the V12 kit fits my 1988 Jaguar XJS (5343ccm, 217kw)?
    also please answer me whether a diagnostic device is necessary when assembling the kit because I do not have such a device
    if so, please confirm and send me the price and details for the order and payment.

    • Hi Thomas If your 1988 V12 is the type with P Digital engine management you dont need any diagnostic device to make it work, I have pre programmed it to suit your engine. It is possible to do adjutments on your own in addition using a usb cable and laptop with tuning software, but it should not be needed. If you have the later type with Marelli ignition I have n program for it right now, but in 2-3 months I will. The basic kit is 3676 euro + vat. And I advice strongly to also have the Lambda sensor option at 150 euro.
      If you want to order we do the details by email

    • Hello again
      my v12 has a LUCAS ECU, so i think the kit fits this engine.
      I want to order a kit with a lambda sensor, as you recommend.
      I am interested in the following: WHAT IS THE DELIVERY TIME FROM THE MOMENT OF PAYING THE INVOICE, is there a guarantee of what it includes and how long it lasts?
      also whether there is documentation for the correct assembly of parts (eg installation scheme, tightening torques, pictures of correctly newly installed spare parts …)
      in the end, do I have to pay VAT when ordering? I would not like to pay twice because I have to pay VAT when importing into Macedonia

Leave a Reply

Your email address will not be published. Required fields are marked *