I see the picture but it does not explain what change was made. Can you tell us what we are looking at?

Mark

 

Do you mean you ground off the crank position sensor bracket from the timing chain cover and fabricated your own?
Or the earlier models have detachable crank position sensor bracket?

 

It looks to me, that the mounting holes were slotted, and the timing fingers were made adjustable by rotating the whole part. This is exactly the same effect "Andys" bracket has on the 6cyl cars.

 

Hmm that makes sense.

Actually the bracket of V12, at least on later cars, is casted with the timing cover, so it has to be ground off and fabricate a new one to adjust the sensor. I found it easier to modify the timing disk, for I had the experience of replacing the crank damper.

Anyways I have to thank Andy for providing the timing advancing idea.

 

Yes, I fabricated slide dracket.

 

I see, that is better than my idea, for timing is adjustable as you said.

Either way, I really like the idea of advancing the timing a bit. It really changes the engine feel.

 

I'm very interested in this mod, are you still running it? does the main EFI ECU control the timing or is it done purely by the ignition modules? I can't find much information on this system.

 

I found the answer to the ignition timing question here:
https://www.jaguarforums.com/forum/x...please-160128/
The controller looks quite simple has anyone managed to remap it yet?

 

Forget re-mapping the Marelli, without the correct software to talk to the ICU or a Datascope to reverse engineer the communications protocol, this is before you even get to the configuration it's not happening.

I am going Megasquirt, but any programmable ECU will do the job.

If the ECU has 2 ignition outputs you can drive the Marelli (actually Bosch) ignitors directly and keep the Dissy. Alternatively (and the route I'm going) is to get an ECU with 6 ignition outputs and run coil packs.

You can change base timing on the Marelli by moving the relationship of the sensor to the 3 tooth wheel. This will change base timing and too much could make the car harder to start. The 3 teeth on the wheel indicate TDC for each piston on the A bank and the ICU then calculates TDC for the B bank.

Slotting the holes in the wheel will make it difficult to adjust timing, better to make the sensor adjustable.

 

Challenge accepted; I spent a couple of hours digging out data and it looks to be achievable. My concern with slotting the trigger wheel is that it might not be able to take extra advance at full load and that I would have to reset it every time I go for an annual inspection. I'm in the UK where 98 RON is everywhere so I may be able to gain a little more.

 

How are you going to communicate with the ECU, AFAIR Marelli run a proprietary communication protocol.

 

There isn't any need to communicate with the ECU, they can't be programmed in-situ. The stock processor is a 'read-only' device although there is supposedly a method for working around that, I have ordered some chips to experiment with. The processor needs to be replaced with a programmable device to allow tuning and it will need to be removed to programme it.
The diagnostic link could be useful, do you know what data is available?
I also need to source a spare ECU to play with, I won't run the risk of bricking mine - at least not until the end of summer!

 

Of course it will be a EEPROM, I can be dumb sometimes.

Its been 25 years since I have programmed EEPROM's so my memory may be a little foggy, We went to Flash in the late 80's. You will need a EEPROM reader/programmer and then if you can read it all you will see is HEX or ASCII without the Marelli decoding utility.

I did think about this, but the MS2 option was far easier. I have a spare Lucas ECU case that the MS PCB will be mounted in. So anyone looking (unless they open the Lucas up) will not know the car is running a Megasquirt.

The MS is fully programmable and has reasonable support in the forums.

 

Its a PROM in the stock processor, EPROM in the windowed processor. It uses a bootstrap programme to write and verify the PROM, there is no read capability hence the need for a bit of skulduggery which will require some custom circuitry and software. There is no need for any Marelli decoding utility its a standard Motorola 68705 processor so any compatible disassembler will be adequate.
I found this document on-line which appears to be the same PCB:
http://www.dinoplex.org/PDF/Marelli%...%20Diagram.pdf there is a lot in there for an ignition only controller but I expect 50% of it is support for fail safe operation.
I'm familiar with MS I looked at it a few years ago but dismissed it, to make it DIY they have made a lot of compromises.

 

If you can reverse engineer it and offer an exchange I'm sure the XJS and Ferrari guys would be interested.

MS has come a long way in past couple of years. I bought a lot of 4 MS2's and I am in the process of modifying one to run the V12 in wasted spark.

 

is that moving the sensor instead?
and how would that be best accomplished?

 

we have 93 (I think 98 RON) here and can get 104 (what ever RON) racing fuel but it cost more
I was wondering if you could have done 10 degrees and pull the timing remap jumper... to run on the premium (93 here)
and place it back if you can get the 104 racing gas...?
ok
http://www.fitfreak.net/forums/fit-d...ark-plugs.html
http://www.racegas.com/article/10
might not do that....

just a thought
also
might I inquire the distance of the center to the slot you made and the distance from the center to the arm that is sensed?
thank you respectfully
Jonathan

 

I don't have an idea for the 1st question... At least 10 degree advance without pulling a jumper plug causes knocking frequently (my acquaintance did that though I recommend not to) on 98RON fuel.

As for the 2nd question, please refer the picture of the page 1. I have already uploaded the dimension.

 

If memory serves me well in the UK the HE engine was originally tuned to run 100 octane fuel, what we used to call 5-star petrol - in those days it was, of course, leaded fuel.


Edit: 5-star was 101 octane, we can still get 99 octane but 98 is more readily available.

 

the Sunoco 260 GT street legal 104 is 10.00/gallon so that will not be an option I will pursue...