Marelli ignition timing tune possible?
#41
08-24-2016, 11:09 AM
Banned
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.
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.
Good luck all the same
#42
08-28-2016, 02:57 PM
Member
James please be aware that the Marelli MED120B as described in the site you linked to and fitted to Ferrari Testarossa is not identical to Marelli MED123E fitted to V12 Jaguar so information on the former is of limited use to those wishing to reverse engineer 'our Marelli'
Good luck all the same
Good luck all the same
Yes I noticed that, comparing the two PCBs the primary difference looks to be in the position sensor interface which is a VR sensor for the Ferrari but is a logic signal in the Jaguar setup. the main architecture looks to be the same. ECUs from the same manufacturer and era tend to be variants of each other rather than being unique.
The Marelli system is a little different from many ECUs of that era because the processor has an internal ADC and external timers rather than the more conventional set up of an external ADC and internal timers. I'm currently looking to source a spare ECU to do the experiments on.
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#44
08-28-2016, 04:16 PM
Veteran Member
#45
08-28-2016, 08:52 PM
Veteran Member
Yes I noticed that, comparing the two PCBs the primary difference looks to be in the position sensor interface which is a VR sensor for the Ferrari but is a logic signal in the Jaguar setup. the main architecture looks to be the same. ECUs from the same manufacturer and era tend to be variants of each other rather than being unique.
#47
08-31-2016, 10:08 AM
Veteran Member
I woke up this morning remembering a little tidbit from 1978.... setting cam timing on my 1275 build (10k cam) chain dives only set one link or another... you can get NEAR your timing setting but to get the cam right on.... there is (dah dah duh)
The OFFSET Woodruff key!
would a offset Woodruff key do the same thing as JapThugs' MOD?
(Looking into it...) the cam timing and the front damper use different Woodruff keys
and can be set independent of each other....
sadly, do not think there is enough overlap to get 5 degrees...
The OFFSET Woodruff key!
would a offset Woodruff key do the same thing as JapThugs' MOD?
(Looking into it...) the cam timing and the front damper use different Woodruff keys
and can be set independent of each other....
sadly, do not think there is enough overlap to get 5 degrees...
Last edited by Jonathan-W; 08-31-2016 at 10:45 AM.
#48
09-01-2016, 05:40 AM
Veteran Member
#49
09-01-2016, 03:54 PM
If you ever experienced Andy's timing advancing bracket for AJ16, which advances the timing 5 degree, you know how wonderful it is and it causes no negative effect.
Hence I tried this mod. 5 degree is not a problem at all. Moreover, it does change the engine character. No negativity.
As someone said before, it will be better to fabricate the crank sensor bracket than to slot the timing disc. It can be done without disassembling the fan unit, belt pulleys, harmonic balancer etc... In addition you can easily change the setting. 10 degree will be dangerous. 5-6 will be the safe point.
Hence I tried this mod. 5 degree is not a problem at all. Moreover, it does change the engine character. No negativity.
As someone said before, it will be better to fabricate the crank sensor bracket than to slot the timing disc. It can be done without disassembling the fan unit, belt pulleys, harmonic balancer etc... In addition you can easily change the setting. 10 degree will be dangerous. 5-6 will be the safe point.
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#51
10-19-2017, 03:03 PM
Member
#52
10-20-2017, 03:52 AM
Veteran Member
If you ever experienced Andy's timing advancing bracket for AJ16, which advances the timing 5 degree, you know how wonderful it is and it causes no negative effect.
Hence I tried this mod. 5 degree is not a problem at all. Moreover, it does change the engine character. No negativity.
As someone said before, it will be better to fabricate the crank sensor bracket than to slot the timing disc. It can be done without disassembling the fan unit, belt pulleys, harmonic balancer etc... In addition you can easily change the setting. 10 degree will be dangerous. 5-6 will be the safe point.
Hence I tried this mod. 5 degree is not a problem at all. Moreover, it does change the engine character. No negativity.
As someone said before, it will be better to fabricate the crank sensor bracket than to slot the timing disc. It can be done without disassembling the fan unit, belt pulleys, harmonic balancer etc... In addition you can easily change the setting. 10 degree will be dangerous. 5-6 will be the safe point.
#53
10-21-2017, 07:44 AM
There is no way of doing this without massive reworking on the timing cover plate. The screw holes are cast into the cover and the sensor sits between them. You'd have to grind off one of the mounting points, weld on something etc. - a lot of work for maybe a few gains which won't really do anything because the Marelli V12 is basically the perfect ignition setup.
So I fabricate the timing plate. slot the hole and cheat the sensor + ecu. It did change the engine characteristic. There is always a margin when engineering the engine, and with 100 ron and very clean gas in japan you wont have any problem by advancing 5 dgree. it revs sharper and you can feel the power gain.
Last edited by Japthug; 10-21-2017 at 07:46 AM.
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#54
10-21-2017, 01:09 PM
Veteran Member
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#55
10-22-2017, 03:04 AM
Veteran Member
Oh, so JapThug is the guy who runs this site!
ƒWƒƒƒKーX300／XJS ƒƒ“ƒe情••ƒpーƒc”ﾌ”„ HP‚ﾖ‚‚､‚ｱ‚ｻ！
I've found it very helpful. Especially for replacing my stereo. Some of the stuff shown there is pretty impressive, and beautifully documented.
いつもお世話になっております！
(Okay, that was a website when I added the URL - still is, but looked really weird. Major 文字化け....)
ƒWƒƒƒKーX300／XJS ƒƒ“ƒe情••ƒpーƒc”ﾌ”„ HP‚ﾖ‚‚､‚ｱ‚ｻ！
I've found it very helpful. Especially for replacing my stereo. Some of the stuff shown there is pretty impressive, and beautifully documented.
いつもお世話になっております！
(Okay, that was a website when I added the URL - still is, but looked really weird. Major 文字化け....)
#57
10-22-2017, 06:18 AM
Oh, so JapThug is the guy who runs this site!
ジャガーX300／XJS メンテ情報＆パーツ販売 HPへようこそ！
I've found it very helpful. Especially for replacing my stereo. Some of the stuff shown there is pretty impressive, and beautifully documented.
いつもお世話になっております！
(Okay, that was a website when I added the URL - still is, but looked really weird. Major 文字化け....)
ジャガーX300／XJS メンテ情報＆パーツ販売 HPへようこそ！
I've found it very helpful. Especially for replacing my stereo. Some of the stuff shown there is pretty impressive, and beautifully documented.
いつもお世話になっております！
(Okay, that was a website when I added the URL - still is, but looked really weird. Major 文字化け....)
Didnt know you have such a beautiful website... Could you let me add it to the link of my page?
#58
10-22-2017, 06:24 AM
Veteran Member
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