Toyota coil paks

[Howard Chu]

I've been going thru this exercise with the LS1 coils already, but
your idea with the 1-of-n decoder sounds good. I've got a V6 so I
need to figure out how to kill two states of a 3-bit count. The
Mazda KL engine already has a camshaft position sensor and two crankshaft
position sensors, and a CID signal so no additional sensor hardware is
needed to identify cylinder 1. The big problem is getting sufficient
dwell time at high RPM, you need to charge the coils for longer than a
single cylinder-time. As mentioned before on this list, the LS1 coils
will auto-discharge after being charged for .1 seconds. This tells me
that it is safe to keep them charged for up to that long. At 650rpm
(idle speed) the interval between cylinder firings is only .031 seconds
(for a V6, even shorter for a V8) so in practice you should never see
a 0.1 second charge time anyway. So my approach would be to start charging
a specific coil one position early, so you have two cylinder intervals
available to charge (max .062 seconds at idle, min .0057 seconds at
7000rpm). On my V6 this allows adequate charge time up to about 8000rpm (and
my rev limiter is at 7500rpm so this is good). My only concern is that this
means for some huge percent of time I'm charging two coils simultaneously,
drawing however many amps to do it. I'm surprised at the 6.5amp figure in
the previous email, I've seen coil specs of about 1.x Ohms, which given a
12-14V power supply means around 10-14amps of charge current per coil. If
it's really self-limiting so that it peaks out at 6.5amps and then tapers
off, I guess this isn't a big issue.

  -- Howard Chu
  Chief Architect, Symas Corp.       Director, Highland Sun
  http://www.symas.com               http://highlandsun.com/hyc
  Symas: Premier OpenSource Development and Support

> Date: Thu, 15 Nov 2001 14:43:28 -0600
> From: don.broadus at exeloncorp.com

> The Toyota 90919-02238 pak is 6.5 inch long
> from boot to top of connector. They look very
> much like the Ford  DOHC COP paks.you could
> connect a plug wire and remote mount the pak.

> - -----Original Message-----
> From: Jay Vessels [mailto:jvess01 at yahoo.com]
> Sent: Thursday, November 15, 2001 12:50 PM
> To: gmecm at diy-efi.org
> Subject: RE: Toyota coil paks
>
>
> Hi there!
>
> First, has anyone yet figured out the app. these coils
> are for (i.e. year, model, engine size)?  How big are
> they?
>
> How 'bout this for a drive circuit for sequential coil
> firing (versus waste-spark)?  I'll use a SBC as the
> example but this would work for any distributor car
> with some adjustments.
>
> Mount a Hall Effect sensor in the timing cover so you
> know where #1 is.  Distributor stays in, timed
> normally, EST system intact including module, but no
> coil or plug wires (of course).  On an SBC this gives
> you an easy way to get timing advance as well as an
> oil pump drive.
>
> A 3-bit counter (4-bit 74xx part, set to count 0-7
> then repeat for an SBC) drives a 1-of-n decoder (SBC
> wants 1-of-8).  Counter increments each time the
> module triggers.  Each output line of the 1-of-n
> decoder turns on an indivdual CMOS switch (a pair of
> 4066 parts would work) whose input is driven by the
> EST module and whose output is connected to an
> indivdual coil.  The Hall Effect sensor is used as the
> input to the counter reset line so it can sync with
> the engine.  Might want to have a disable such that it
> doesn't fire ANY coil until the Hall Effect cam sensor
> triggers the first time so no coils are ever fired out
> of sequence.
>
> This method lets you drive n coils indivudually, fires
> them in sequence when the ignition module fires the
> coil (giving you spark advance), and is syncronized
> with the engine through the cam position.
>
> Coil dwell time might be a concern, and there might be
> some circuit timing issues (i.e. make sure the counter
> increments on the falling edge since you'll want it to
> increment BEFORE firing the coil on the rising edge)
> but it sounds reasonable to me.
>
> Doesn't seem to be that complicated of a circuit, the
> hardest part being mounting the cam timing sensor.
> Other issues include the normal EMI and automotive
> power supply concerns.  Just an idea off the top of my
> head.  Anyone care to pick it apart (there's gotta be
> holes in it)?
>
> Jay Vessels
> 1982 Chevrolet S-10 Sport, 2.8V6 TBI
> 1994 Chevrolet Cavalier Z24 Conv., 3.1V6 MPI
>
> - --- don.broadus at exeloncorp.com wrote:
> > I have been kicking around a couple ideas.
> > a real crude one for carb apps.would be
> > to add a brush terminal to the rotor to
> > physically make contact with each cap terminal
> > the centrifugal advance would move the rotor
> > to provide limited advance.  The coil term
> > would have +5 VDC on it. A better idea would
> > be an optical shutter wheel. EFI apps. A crank
> > trigger advanced 36 deg would trigger a one shot
> > timer that would be  delayed to clock a
> > counter to fire at 0 deg TDC or no delay
> > for full advance ,might be possible for the
> > EST line to control the one shot. A 4017
> > counter IC would be a good start.
> > Just prelim thinking.
> >
> > -----Original Message-----
> > From: Jeremy Gonyou [mailto:jeremygonyou at yahoo.com]
> > Sent: Wednesday, November 14, 2001 6:54 AM
> > To: gmecm at diy-efi.org
> > Subject: Re: Toyota coil paks
> >
> >
> > Hi Don,
> >
> > How are you controlling those coils?
> > Coil on plug would be a cool project for P4s.  I
> > think
> > it would take some serious EE work unless there is
> > an
> > external controller available...
> > Thinking aloud.  Anybody have similar ideas?
> >
> > Jeremy
> >
> > > Stompin around the junk yard last night
> > > I found 4 Toyota 90919-02238 coil on plug
> > > paks like the LS 1 uses. The car was
> > > crushed so I don't know what year it
> > > was. It was a 4 cyl. DOHC. Until
> > > I can find some LS1 paks the
> > > Toyota ones will work. The connector is
> > > marked 1,2,3,4
> > > 1= +12V
> > > 2=ground
> > > 3=TTL signal
> > > 4=ground
> > > a 5 volt TTL low to high transition will
> > > fire the coil. They draw 6.5 amps even
> > > up to 1KHZ square wave. great spark even at .060
> > > plug gap.

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