Anyone thought about Hall/wasted spark?

[Brad-ManQ45]

Please consider this as a request for enlightenment, and possibly a new avenue for those of us who don't wish to use EDIS as their means for ignition control, if only because of the trigger wheel needed. SDS does it all with flying magnets and a hall sensor without a distributor, so MSnS_E should be able to also.

 

I have been poring through the MSefi forums and MSnS_E sites trying to figure out if it is at all possible to do wasted spark with MSnS_E with flying magnets on the dampner and hall sensor, using 3 coil paks and 3 ignitors.

 

Since I am not electronically inclined, pardon my use of laymans/possibly incorrect terms and probable misunderstanding of some basic concepts.

 

My first concern is that unlike a 36-1 or 60-2 wheel, which has its' own indexing, how to tell MS which set of cylinders to fire when.

 

If this can in fact be done with only the three magnets (as SDS does), great and the question is - HOW?

 

If there has to be an index signal of some sort, my thought was to mount another sensor that would provide a signal at the same time as the magnet for the #1 cylinder pair would and feed that to MS somehow.

 

I havd no intention of giving up A/C or power steering on my '83ZXT, and really don't want to spend $500+ dollars on an aftermarket dampner/pulley set to allow the use of EDIS - or even the 36-1 or 60-2 wheels in order to go wasted spark.

 

I havde searched through this forum and the MSEFI forum and haven't gotten very far, possibly due to mky aged brain.

 

Any thoughts and illumination would be greatly appreciated.

[sims76]

Brad,

 

When you made this post, I had to do some digging and figure it out....I think I got it.

 

Notice how the SDS crank sensor in the upper right hand corner has two pickups? It appears that you can configure megasquirt to take the RPM input from one pickup and then just put a single post somewhere else to take care of the indexing. The bad news is that it looks like it requires some additional hardware on the MS end (duplicate tach conditioning circuit).

 

The following is from the MSnS extra website.

http://megasquirt.sourceforge.net/extra/select.html#edis

Nippondenso dual wheel / 2nd trigger

Click here for more

Many Mazda and Toyota engines utilise Nippondenso ignition which uses a dual wheel crank angle sensor (CAS) which has one 24 tooth wheel and a 2 or single tooth second wheel.

This option can also be used inventively to give 4 cyl COP or could be used with the dual pickup crank trigger from SDS for 4cyl wasted spark.

[z-ya]

Hear is a good source that shows you how to sewt up MS for just about any wheel. There are many examples at the end of the page.

 

http://megasquirt.sourceforge.net/extra/setup-wheel.html

[Brad-ManQ45]

Thanks guys:

 

I had already been to those pages and figured out that I could have one magnet reversed (sensor wiring too) but didn't get the 2nd trigger part.

 

The other option is simply using 5 magnets with 60 degrees between each, and two with 120 degrees between them.

 

This will enable me to use the wheel decoder and avoid the neccesity of the 2nd trigger, which I don't think MSII will have in the near future.

 

Yes, I said MSII - I've been paying attention to the MS forums and fairly quickly there will be support for most of what I at least am looking for, which will make me feel better about using huge injectors.

 

Thanks again.

[z-ya]

To be honest, I don't like the idea of magnets on the crank pulley. The 81 ZX turbos had them, and they are know for flying off. With all the effort you will need to put into this non standard setup, I'd just mount a 36-1 wheel and be done with it. Then you can use all the standard MS code

[Brad-ManQ45]

Since I have an '83 and don't know how the 81's were mounted, I intend to drill into the dampner and epoxy the magnets in.

 

Numerous SDS users have gone this route and don't have problems.

 

By putting 12 magnets around the pulley, one reversed, I will duplicate a 12-1 missing tooth wheel and be able to use the MS standard code.

 

Seeing what others have done to mount a 36-1 wheel, I would have to lose a pulley which I am not ready to do - nor go with a serpentine belt system.

 

By using magnets, I don't have to deal with a VR conditioning circuit either.

[sims76]

Brad,

 

I think you're on a very practical track. I currently use a "Omnipolar Hall-Effect Digital Switch" from http://www.allegromicro.com

 

I ordered a second batch of samples last week. I just pot them in JB weld on a piece of alumimum and they are good to go.

 

What are you going to use for the ignitors?

[Brad-ManQ45]

I'm thinking the VB921's.

 

There is a possibility thatr I will use a Volvo ignitor that has 3 channels to drive 3 coilpaks - p/n: 0 227 100 203. This is also under investigation.

 

I have to wait, because I want to use MSII on my turbo, and they don't have the wasted spark code in yet - but it appears to be coming.

 

I want the MSII because later on I will be taking out the T5 and putting in an automatic (daily driving around Atlanta sucks with a manual, and I intend for this to be a daily driver. Megashift is intended here.

 

My wife's work is relocating further away and I want to keep the miles off my Q45a that she is driving right now.

 

I'll let her use the Town Car I am driving now, or maybe she'd rather drive the Z!