the other post (Fwd) Re: hall sensor on a '85 4kq? (5 window type?)

[auditude at neta.com]

I finally got the bounce from the message I mentioned before.  This
one is also before Orin's great post I just received.  Very good info,
thanks, Orin!

Ken

------- Forwarded message follows -------
From:           	auditude at neta.com
To:             	JShadzi at aol.com, <quattro at audifans.com>
Date sent:      	Fri, 25 Jan 2002 18:42:59 -0700
Subject:        	Re: hall sensor on a '85 4kq? (5 window type?)
Priority:       	normal

Hi,

I think maybe the posts are getting crossed, as this one is still
talking about using the 5 window hall sensor distributors, and I've
since posted that I'm going to try to go with the MAC11 distributor
"because I think I have to" to have crank triggered ignition timing.

But that's cool.  I'm going to reply, because it's still good info for
myself or anyone else who's going to use the 5 window style
distributor.

On 25 Jan 2002, at 20:00, JShadzi at aol.com wrote:
>
> > So, if I don't want my hall signal to advance under vacuum, I should
> > disconnect the advance (see question below, regarding the effect of
> > vacuum advance on hall signal)?
>
> Yes, or be done with it and use the NG/NF dist.  With programmable
> ignition you don't want vacuum advance.

Well, I am going to be running sequential fuel injection, so I need to
know whether the no.1 piston is at TDC compression or TDC
exhaust.  Therefore, I don't think I can use the 5 window at all.  I
am trying to avoid putting pin and hall sensor on the front of my
cam at the timing belt gear.

If I were to use the 5 window, I don't think I'd be buying an NG/NF
distributor, if I can just use the 4kq one I have, after disabling the
vacuum advance, for free.

> > > > Does the hall signal itself change with the vacuum advance, or
> > > > is the hall signal constant?
>
> > I meant, is the timing of the hall signal affected by the vacuum
> > advance, or is it just the spark that's affected?  Here I am
> > probably really showing my ignorance.  I will physicaly look at my
> > distributors when I get home to see what I'm asking about.
>
> Mute since you won't be using it, right?

Basically yes, but I still would like to understand how it works. :-)
Since you misunderstood that question the first time, I was still
wanting an answer.  I like to close issues out and gain some
knowledge rather than get so close to understanding something
and then just let it go.

> > > > I think I would still have to incorporate the timing reference
> > > > pin in the flywheel for my system to function correctly.
>
> Ok, last time, use your dist hall for RPM info, and use a pin in the
> crank/cam/flywheel for a TDC signal..

I must be bugging you now, sorry about that.  I don't remember
anyone anywhere (specifically) mentioning that I can use the
distributor hall for rpm info.  Sorry if I missed that earlier.

Is this with the 4kq distributor, the MAC11 one, or both?  I can't tell
if you are talking about a sequential application or batch mode.
Maybe it doesn't make a difference, but it seems to.

You can eliminate the crank and flywheel for a TDC signal in my
application, since it's sequential. You can eliminate the cam as the
only TDC signal too in my application, since I want my ignition
crank-driven.

Maybe I can use either the reference pin or the distributor for RPM
info tho', if there's an advantage to that.  Is accuracy not a problem
for the rpm calculation when taken from the distributor hall sensor?
I mean, it's the difference between 135 points of reference on a
large diameter flywheel, compared to (are we talking 1 window or
5?) the much less points of reference on the much smaller
diameter hall sensor.

I'll just summarize where my thoughts are, I've been trying to figure
this out most of the day, and I'm getting a little burnt out on it.  I'm
still excited, but I may have had enough for one sitting.

1.  I want my spark to be driven off the crank and not the cam.

2.  I'm going to be running sequential fuel injection, timed with valve
opening (at lower rpms).

3.  The crank can't tell the ECU whether the piston is at TDC
compression or exhaust.

4.  To do the above requires either a homemade cam trigger, or the
stock single window, MAC11 distributor/hall sensor.  I can't use the
5 window in this scenario at all, because my no.1 cylinder isn't
going to be at TDC compression 5 times, just once in the same
amount of time(?).

Right now, the 5 window distributor is an excellent "Plan C" for my
setup, if I can't use the factory sensors (rpm, crank position,
stroke) "Plan A", and can't fabricate a crank-driven "Plan B".

One question I might have for the LinkPlus people is whether they
can use the single timing reference pin on the flywheel as both the
timing reference AND the rpm signals.  Since you say that I can
use the distributor hall sensor for rpm, and it is traveling half as fast
as the crank, it would be twice as accurate.

I hope that's a good wrapup of all the considerations I have to
include.

Now I just have to find out if they can use the stock teeth and pin,
or just the pin, and the single window hall sensor.

Thanks for your help Javad.  You are much further along in all this
than I am.  It was only mid-December that I even thought of going
with EFI at the same time of the MC-1 swap.  And it was only
yesterday that I was asked for the specs on the stock setup.

Any comments will be greatly appreciated, especially if I'm still
confused and wrong about something(s).

Later,

Ken

------- End of forwarded message -------