Mercedes W114 250 Coupe - help!

[grober]

Having had a quick perusal of the M110 megasquirt conversion referenced early on in the thread and a quick look over the MEGASQUIRT PAGES perhaps your choice is between a wide band or precision approach.
The first would use MS2= linked injectors 2 blocks of 3 bit like a CIS System and together with a relay board and 3 power transistors + 3 double coils --a lost spark ignition system. [ bit of fabrication required ]
The second MS3+ the MS3X expansion card = individual control of each injector and individual spark plug coils [ more turnkey but more expensive]
I'm sure the guy who built your Citroen system will advise.

 

[Bellow]

Home of the Emerald K6 aftermarket standalone ECU

EmeraldM3D.com - K6 ECU Info & Specification

Engine management (ECU, EMS) & conversion kits

 

[grober]

Home of the Emerald K6 aftermarket standalone ECU

EmeraldM3D.com - K6 ECU Info & Specification

Engine management (ECU, EMS) & conversion kits

Interesting comparison here.
Megasquirt or Emerald - PistonHeads

 

[Charles Morgan]

Every spark is sacred
Every spark is great
If a spark is wasted
God gets quite irate.

My head is currently hurting through lack of sleep last night, but could someone inform me what a wasted spark is.

 

[grober]

Its found in double coil systems when two spark plugs are fired at once--- This isn't so daft as it sounds as in one cylinder the piston is rising on a compression stroke with a nice combustible fuel air mix waiting to be ignited and both valves shut. The other piston rising at the same time is on an exhaust stroke with waste gases flowing out an open exhaust valve--- hence its spark is " wasted" as there's nothing to ignite.

 

[Bellow]

Its found in double coil systems when two spark plugs are fired at once--- This isn't so daft as it sounds as in one cylinder the piston is rising on a compression stroke with a nice combustible fuel air mix waiting to be ignited and both valves shut. The other piston rising at the same time is on an exhaust stroke with waste gases flowing out an open exhaust valve--- hence its spark is " wasted" as there's nothing to ignite.

The beauty here is two-fold. Firstly it cuts in half the required quantity of drivers. Secondly and probably crucially here - double ended coils (as used by wasted spark systems) mount the coil anywhere appropriate and run a HT lead to each of the paired plugs. I've yet to see a coil-per-cylinder (as would be required by a non wasted spark set-up) be anything but the type as installed on 4-valve per cylinder motors. That is, tall, and supported by the (deep) spark plug well. I can't imagine them being anything but a liability for this application.

For now, I'd look at the suitability (wrt timing curve/advance) of the Ford EDIS set-up (if indeed Ford timings apply - probable (and likely to vary between outwardly similar 6 cyl motors eg, V6 Explorer OHV with 2 different heads or OHC version!)) and the programmable versions that have 3 drivers for 3 x wasted spark.
How's the head ache now?

 

[Bellow]

Interesting comparison here.
Megasquirt or Emerald - PistonHeads

Stuck with it until third page...it is a five year old thread bear in mind.
There's a post on second page that says all MS systems for fuelling must also run ignition, but the first system on the MS page has a system where 'with modifications' it can also run (Ford) ignition.
I was wondering if retaining elements of the original MB system isn't viable (assuming the dizzy is serviceable) to retain the timing curve. Is there not a method of electronicising it (using later MB hardware)? Programming ignition timing could be a bit of a chore - especially without a detonation sensor as a safety back up. Swinging the (pre-programmed) dizzy to find the sweet spot for 21st century fuel a breeze in comparison. Wondering what the SM uses.
As for programming the fuelling I guess CM's SM MS man will know what to do and how to do it though I'm not sure if a fair amount of this will have to be done be AN Other as said man isn't resident in the UK IIRC.
Anyway, enough of my babblogue - we'll see what the man in charge has to say as to the direction of travel soon enough.

 

[Charles Morgan]

Dizzy is corroded and not serviceable.

The recommended replacement is a 123 - there is one made for the car which is pre-programmed with the existing timing curve.

The question is then integrating it with the MS/Emerald/ANother ecu.

The SM ignition is run by a bespoke van Rootselaar dizzy connected to a coil with sensor (how or why is beyond me).

While Nard and Jeroen at Autotune are excellent on the SM (and other cars) I don't think what they do is particularly unique and being in Holland, a bit of a bore logistically. I'm inclined to join the MS forum to start getting my brain around it.

Perhaps one could refer to my chap as the CM SM MS MC for a total acronym palindrome...

 

[John Jones Jr]

Forget about using a dizzy imo. Opt for full ECU control of both fuel & ignition (using EDIS coil). Have a look for posts online, it's common practice on the likes of M102;s & M103's also.

 

[grober]

That dizzy [ credit to Pontoneer for that one orginally] would certainly solve a lot of problems. The orginal Djetronic distributor would have had a couple of extra contact breakers in the base of course for triggering the firing of the 2 banks of three injectors --- they do specifically mention version 123\MERCEDES-6-R-V-IE for D jetronic setups- I assume that version provide these extra pulses OUTPUTS as well as the HT "distribution" ? That said the pulses could alternatively be provided via a front crankpulley toothed wheel +hall type sensor instead. The distributor would be a nice touch certainly make the engine look more authentic/of its time looking.

 

[John Jones Jr]

That dizzy [ credit to Pontoneer for that one orginally] would certainly solve a lot of problems. The orginal Djetronic distributor would have had a couple of extra contact breakers in the base of course for triggering the firing of the 2 banks of three injectors --- they do specifically mention version 123\MERCEDES-6-R-V-IE for D jetronic setups- I assume that version provide these extra pulses OUTPUTS as well as the HT "distribution" ? That said the pulses could alternatively be provided via a front crankpulley toothed wheel +hall type sensor instead. The distributor would be a nice touch certainly make the engine look more authentic/of its time looking.

That's about it, I reckon.

I also reckon as this is a very old engine design it needs all the help it can get to maximise performance/efficiency. Just controlling fuel from a modern retro fit ECU like Emerald, Motec etc it's only half doing the job. Again all imo.

 

[Charles Morgan]

That's fair enough. I shall research all the options, engine bay aesthetics are important though, it's why I rejected coil packs for the SM, which has certainly benefitted a lot (the 2.7 engine now compares in performance and economy to the much later PSA 3 litre V6).

 

[grober]

The more I think about it the more I am coming round to the idea that copying the set up described on that M110 megasquirt conversion might be a good idea. Why re-invent the wheel when many of the snags fuel maps etc have already been dealt with. The bore stroke ratio of the M114 and M110 are remarkably similar meaning I imagine the power torque fuelling demand profile over the rev range should be similar also.???
M110---86x78.8

M114---81.7x78.8


280SL "K-Jet and Ignition conversion to Megasquirt" write up - Mercedes-Benz Forum

I particularly like that air fuel ratio gauge linked to the lambda sensor as a check on fueling settings.- indeed it would be worth incorporating a port for one into the exhaust if one did not exist already.
Mercedes-Benz Forum - View Single Post - 280SL "K-Jet and Ignition conversion to Megasquirt" write up

 

[Bellow]

Reprogramming the ignition timing correctly will give you precisely the same map as MB developed back then - but at enormous cost in wear on the dyno. The combustion chamber is the same as it was then and only advancing or retarding slightly (the whole curve in one adjustment) to compensate for fuel of different octane is required IMO. The improved electrical output from electronics allied to the existing knowledge of the engine's timing requirements will save having to reinvent the wheel.
If this were a bespoke turbocharged engine, yes, remap the ignition. It isn't.

 

[John Jones Jr]

I don't think the distributor would be missed judging by the above photo. An alloy blanking plate fitted in it's place and the coils mounted under the battery tray, job done.

 

[John Jones Jr]

Reprogramming the ignition timing correctly will give you precisely the same map as MB developed back then - but at enormous cost in wear on the dyno. The combustion chamber is the same as it was then and only advancing or retarding slightly (the whole curve in one adjustment) to compensate for fuel of different octane is required IMO. The improved electrical output from electronics allied to the existing knowledge of the engine's timing requirements will save having to reinvent the wheel.
If this were a bespoke turbocharged engine, yes, remap the ignition. It isn't.

Sounds like I purchased the wrong aftermarket ECU for my N/A engine...

 

[grober]

I have seen other M114 engines with that cover- perhaps as water shield? Others without it. I sorta like the traditional "spaghetti hoops" look with that red cap but its really down to Charles' personal taste.

 

[Bellow]

The recommended replacement is a 123 - there is one made for the car which is pre-programmed with the existing timing curve.

The question is then integrating it with the MS/Emerald/ANother ecu.
.

The dizzy in the link will operate as standalone and that it is preprogrammed with the advance/retard curves is invaluable - it will even retard the timing during an auto upshift!

That only leaves the fuelling and as far as I can see the first board on the MS website will accomplish that. From what I've read before, a basic installed fuelling map gets it up and running and is then tweaked (manually I think, but with the option of it being automatic - read more complexity/cost) from data fed back from the WB Lambda. (I have quite a lot printed out re setting target AF ratios at selected rpm/load/ VEs - I'll find it and re-read). Suffice to say that creating a fuel map will be a task enough. Needlessly having to create an ignition map makes no sense to me.
The simpler the better. Hours on the dyno will do the engine no favours.

 

[Bellow]

Sounds like I purchased the wrong aftermarket ECU for my N/A engine...

How long did it take you to map the ignition and what was the financial cost of that mapping?

 

[John Jones Jr]

How long did it take you to map the ignition and what was the financial cost of that mapping?

I reckoned you'd know?

I don't, as it's not fitted yet but guessing somewhere around 3-4hrs @ £100 p.h. from the quotes and info I've received. Actually, the cost is really a non issue against overall cost & benefits of fitting a modern programmable engine management system. I didn't think cost was the issue here, don't recall anybody mentioning it for a reason not to have a fully mapped system. Of course CM's car will require mapping too, so I don't see much validity in your question.