tachometer signal revisted

[Richard Hoffman]

Upon further research, the 4-cyl (3A) and 5-cyl (NG) use the same
tachometer. According to  Jim Green, this tach only responds correctly to
5-pulses per cycle.  Does the 4-cyl ECU really put out 5 pulses per engine
cycle?  Javad, I hope this isn't giving away technical secrets of the 034EFI
ecu, but what is the tach signal output like?
Thanks!
Richard
----- Original Message ----- 
From: "Richard Hoffman" <billzcat1 at hotmail.com>
To: "Jim Green" <jeg1976 at yahoo.com>
Cc: "Quattro list" <quattro at audifans.com>
Sent: Monday, December 01, 2003 2:24 PM
Subject: Re: tachometer signal


> I am using Tec3 which has tach outputs for 1-6 pulses per revolution.  It
> doesn't allow me to use 2.5 pulses per rev.  I suppose I can swap a
> 4-cylinder typ89 tach and use 2 pulses per rev and that would solve all my
> problems.
> Richard
> 90 CQ
> 70 100LS
> ----- Original Message ----- 
> From: "Jim Green" <jeg1976 at yahoo.com>
> To: "Richard Hoffman" <billzcat1 at hotmail.com>
> Cc: "Quattro list" <quattro at audifans.com>
> Sent: Monday, December 01, 2003 2:01 PM
> Subject: Re: tachometer signal
>
>
> >
> > --- Richard Hoffman <billzcat1 at hotmail.com> wrote:
> > > This isn't going to work for me as I have no
> > > distributor to take advantage
> > > of.
> >
> > Um, what what are you doing again?
> >
> > > So to be clear: the typ89 5-cyl tachometer uses a
> > > square wave, 2.5 pulses
> > > per revolution?
> >
> > Correct
> >
> > > Or does it take an independant
> > > signal from the ECU?  What's
> > > going on here?  I don't have an occiliscope to check
> > > this stuff out :)
> >
> > Nope, I've feed it from the dist, from a Haltech, I
> > think some of the Crane and Msd ign boxes have tach
> > outputs that would work, the 034 efi tack output works
> > great, and could be configured to make the tach think
> > there's 5 cyl there instead of 8 cyl if you did a v8
> > swap. You really just need the 5 pulses per engine
> > cycle to make it work right.  If you're not running a
> > 5cyl, and you were previously, that could be tricky
> > with some management systems.  Who knows, there may be
> > some jumpers on the tach or something that might help,
> > I've never looked.
> >
> > =====
> > Jim Green
> > '89 80q slow
> > '89 90tq fast, really fast
> > http://www.mswanson.com/~jgreen/car_home.html
> >
> > __________________________________
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> >
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