MS2 Wheel Decoder and Trigger Offset Questions

krisr · Post by **krisr** » Mon May 01, 2006 7:57 pm

So theoretically you could set the crank wheel 'tach' missing tooth anywhere as long as you set the correct skip and delay teeth?

I'm just trying to remember back when I fitted a direct ignition HPV-1 to a friends 383 Chev, from memory it HAD to be on #1 TDC firing with the sensor aimed at the trailing edge of the 11th tooth to put it in the ballpark to fire with 0Â° of advance, each tooth after that represented a 6Â° advance before you started to play with the advance on the module itself.

I guess my question is, does it also matter which edge of the tooth you set your sensor on also like the HPV-1?, e.g. I have a 36-1 tooth wheel at the moment. If I rotate the motor to #1 firing TDC, setup the sensor to be on the trailing edge of the 9th tooth my settings would be

Wheel: 36
Missing Teeth: 1
Skip Teeth: 9
Delay Teeth: 9

Post by **grippo** » Tue May 02, 2006 8:46 am

You can set your tach sensor anywhere but there are some considerations. If you want to use trigger rise, then you want to set your sensor to the timing advance you want during starting. The tooth edge doesn't matter so long as it is correctly specified in MT and the trigger offset is measured from the correct edge.

As far as your 36-1 wheel, the skip teeth = 36 / (no cyl/2) = 9 for an 8-cyl car. The next consideration is that the trigger offset is measured with respect to the first tach input following all the missing teeth + delay_teeth. I would set that tooth up to be 8 or 10 deg BTDC. The use of delay_teeth is just a convenience for people who can't easily rotate their wheel or crank sensor to any position. You can make it 0 if you want.. The only restriction is that you can't have a tach input come in on a mssing tooth. So pick a delay tooth that is convenient. Then start counting 9 teeth from that tooth until you come back to where you started. This gives you all the tach in teeth - if any of them falls on a missing tooth, then you have to change the delay_tooth value.

krisr · Post by **krisr** » Tue May 02, 2006 2:16 pm

Thanks for the info Al, that helps alot.

Bengt · Post by **Bengt** » Fri Jun 02, 2006 1:28 am

Hi Lance or Grippo
More question to Renault 5 Gt Turbo cars(controlling spark ).I am installing V3.0 68HC908GP32 processor ,And i see only router will handle that ?.Can the code from router board moves to 68Hc908Gp ? .

Bengt · Post by **Bengt** » Fri Jun 02, 2006 1:40 am

jsmcortina · Post by **jsmcortina** » Fri Jun 02, 2006 3:09 am

Bengt wrote:Hi Lance or Grippo
More question to Renault 5 Gt Turbo cars(controlling spark ).I am installing V3.0 68HC908GP32 processor ,And i see only router will handle that ?.Can the code from router board moves to 68Hc908Gp ? .

You need the MS1/Extra code for that processor, take a look at:
http://megasquirt.sourceforge.net/extra
http://megasquirt.sourceforge.net/extra ... wheel.html

James

Bengt · Post by **Bengt** » Wed Jun 07, 2006 12:20 am

I have 029q2.but long tooth make some hell.

jsmcortina · Post by **jsmcortina** » Wed Jun 07, 2006 4:22 am

Bengt wrote:I have 029q2.but long tooth make some hell.

If you have a specific problem please ask about it in the MS1/Extra forum.

James