Ignition Options, MSII & Siamesed Port Code
Turbo Mini Forums

An issue has arisen that anyone considering the Siamesed Port Code should be aware of.

The new code is based on the new MS2/extra code. It will need the direct connection of the VR sensor into the Megasquirt.

Hence, you cannot use it with EDIS ignition.

It is easily configured to drive a single coil but this will mean you need to keep the distributor to feed the coil output to the plugs. You will still have the advantage of mapped ignition but the distributor will be in the way if you wanted to clear the space for an intercooler.

You can get the Megasquirt modified to include an additional ignition driver circuit that will allow you to run the EDIS wasted spark coils. You will also need the MS2/extra code which is still in development. However, there seems to have been limited success with this and a lot of burnt transistors.

Edited by Paul S on 5th Dec, 2006.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Actually, while it's true that there has been quite a bit of talk about burnt VB921s (ignition driver transistor), I wouldn't say that there has been limited success. It's only that you hear more about the failures that the successes.

If you're really concerned you can always use 2 external smart ignition modules for wasted spark and those module will take care of all the dwell issues. You could also use logic level COPs that also take care of the dwell.

I don't think there is an issue with using the VB921 if you're careful with the installation and make sure that your configuration is set correctly. By the way, even if you use a distributor, you're still relying on the VB921 that is standard on the MS3.0 board.

Jean

http://www.jbperf.com/

Question, maybe a stupid one .....

Could you not run 2 VR sensors next to each other and map out the positional error of the second one in MegaSquirts offset table? That way you could have one feeding the EDIS and the other of the 'Squirt.

Another option is you could syntisise the second pulse from another trigger (done this for test machines at work when there isn't scope for a toothed wheel).

I will speak to our electronics guru this afternoon and see what he recomends and if it is possible to split/duplicate the output from the VR so that one sensor could feeb both the squirt and EDIS.

Good to hear the code is progressing though, excellent news!!

Every day is a school day ...........

How fast and how expensive ...... the same question...

Roger,

I think this will all be resolved once the MS2/Extra code is released. You will be able to run wasted spark coils directly of the MS with one VR sensor. You will still need to add the extra VB921.

You will also, I think, be able to run two VR sensors with the new code. You cannot at present. But then why would you if the MS2/extra will be able to do it all with one VR sensor?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

VEMS is looking more and more attractive

I will be honest and say that im not interested in the siamese code. I think tuning the A series is now beyond that for me. This Siamese is just that bit too complicated and few and far between for any of these ECU systems to take advantage.

I think the best way to get round this whole problem is design from scratch an ECU specificaly for the five port, maybe based on MSII, after all MSII is a make up of all the fancey bits others have added to the original MS, lots of it is not needed and the most important bits are left out.

Take the basic MS and add the bits we need.

Sounds like a plan, any electronics whiz want to take up the challenge

"Most important bits left out"???? What whould they be then, have I missed something????

Got MS2 running on my VW, no probs, MS S&E would have done but not as neatly........

Every day is a school day ...........

How fast and how expensive ...... the same question...

I am a noob to this Megasquirt etc, how exactly does the 'code' solve the siamesed $1M question? Is it using 1 or 2 injectors per port? What sort of dollar difference is an MS compared to a Motec M4pro or equivalent? Is there any light at the end of the tunnel for EFI 5-porter on a budget?

NB - I'm not suggesting that a Motec is the solution either, trust me I know. But it can be used on anything else should you need to sell it, hence the query.

regards

Daniel

First 5-port EFI turbo in the world (built 1997, running in 1998)

Megasquirt is universal too. In fact there is specific code to do most things so maybe more adaptable than Motec. Price difference is huge, MS much much cheaper than Motec even if you buy it prebuilt.

Every day is a school day ...........

How fast and how expensive ...... the same question...

The cost of the Motec in Australia is quite cheap I reckon for the adaptablilty. I can run any sensor or ignition system, crank angle and sync combo either hall or magnetic....

Not to say it's the better option, my query is more what is the siamesed code doing thats different, is it a code of fuel table, injection timing table???

How is the code solving the problem of charge robbing or am I right in reading that it is firing the injectors for the 180deg window of opportunity at maximum hp as figured out by many.

It's a genuine query because I am at the limit with my engine at the moment so I either go to the SU or try something different and want to understand what is happening regarding the megasquirt.

Cheers

Daniel

Edited by DOZ on 8th Dec, 2006.

First 5-port EFI turbo in the world (built 1997, running in 1998)

It is a code to fire the injectors once every 180-crank degrees, but with an 'advance table' such that the start of injecton event varies.

We have a few options on how to do this - but until it is done - which option is best, is not known.

Thanks Dave, that's what I thought, although reading my previous post it's probably not that clear (even I'm confused, it was late last night here in Oz and a few ales had their obvious effect).

cheers

Daniel

First 5-port EFI turbo in the world (built 1997, running in 1998)