VR sensor and Direct fire coil (megasquirt)

[luke]

hi,
I'm after some advice on some bits i can steal from fiesta's puma's escorts etc for converting my '72 beetle to fuel injection.
1st off, can someone tell me where the crank trigger VR sensor is mounted on most ford engines? and secondly, if anybody out there is clued up on megasquirt- for ignition control can you fire the ford four post coil direct from MSII using Bosch BIP 373 transistors or do you HAVE to keep the edis module to fire the coil?

thanks for your help, much appreiated

 

[Peter]

You can't fire the Ford coil pack directly from the MS-II no matter what you do, as the MS-II as standard only has one high current driver so you'll need to add another one in. Best off purchasing a 4 channel driver board from JBPerf and using that to build two ignition drivers and skip the one on the MS PCB.

Pretty sure that you'd be able to drive the coil pack straight from an MS-II using wasted spark firing, AFAIK most people use EDIS as it's standard fit on the cars they use, it's not such a great system to retrofit.

 

[luke]

yeah i dont want to use edis, the megamanual just states that one driver is to be used per coil so i thought id be able to fire 1 coid 4 times per rev in wasted spark no?

 

[Peter]

No, for starters the Ford coil pack is actually a pair of coils, each of which fires twice per engine cycle, ie. once every 360 degrees. If you fired one coil to all four plugs every 180 degrees you'd be firing the coil on each cylinder's intake stroke which would destroy your engine in short order.

This means that you need two drivers for the coil pack, and given that the Ford coil pack is just a normal coil without a built in ignitor you need high current drivers to run it.

 

[luke]

so id be better off avoiding ford coils?

 

[Peter]

TBH I'd just go straight to a Toyota COP setup and use sequential ignition, if you're converting a car which is currently not running an EFI setup you may as well go straight to the gold standard

 

[luke]

and for that i'd need 4x373's, a cam sensor and crank sensor and the 4 coil sticks each fired off their own 373?

problem is where the camshaft is on the vw flat four, to get a cam signal i'd need to keep the dizzy and modify it for cam signal. i think id rather run wasted spark COPs

 

[Peter]

No, if you get the right COPs from a Toyota (there's a whole host of cars that suitable ones were fitted to) then all you need to do is provide a logic level signal to control them, as they have their own igniter built in. That makes life a lot easier, as you don't have to run high current ignition circuits in the MS case which makes wiring a lot easier and also cuts down on electrical noise, which the MS is quite prone to.

There's no reason you couldn't run COPs in wasted spark either, just hook up the correct trigger pins together to fire the correct cylinder pairings. This also means that you can simply wire up the D14 and D16 LED circuits to drive your spark outputs, have a search for the Joe Perez spark mod over on MiataTurbo.net to find out how to do this.

Presumably you're planning on running batch fuel injection if you aren't planning on pulling out a crank signal?

 

[luke]

thanks for the miata heads up
yeah im gonna run batch, its the cam sensor i need foor sequential again isnt it?