DIY_EFI Digest V3 #79
Robert Harris
bob at bobthecomputerguy.com
Thu Mar 5 14:54:43 GMT 1998
-----Original Message-----
From: owner-diy_efi-digest at efi332.eng.ohio-state.edu
[mailto:owner-diy_efi-digest at efi332.eng.ohio-state.edu]On Behalf Of
DIY_EFI-Digest-Owner at efi332.eng.ohio-state.edu
Sent: Thursday, March 05, 1998 2:00 AM
To: DIY_EFI-Digest at efi332.eng.ohio-state.edu
Subject: DIY_EFI Digest V3 #79
DIY_EFI Digest Thursday, 5 March 1998 Volume 03 : Number
079
In this issue:
Re: Crank Trigger Signal (was monitoring RPM)
Re: signal from coil and back emf......
EFI and Mileage
Re: signal from coil and back emf......
Re: signal from coil and back emf......
Re: Crank Trigger Signal (was monitoring RPM)
Re: signal from coil and back emf......
Re: signal from coil and back emf......
Re: signal from coil and back emf......
Re: VSS and freq converter circuit
Re: signal from coil and back emf......
Re: Reference Book
Re: signal from coil and back emf......
Re: signal from coil and back emf......
See the end of the digest for information on subscribing to the
DIY_EFI or DIY_EFI-Digest mailing lists.
----------------------------------------------------------------------
From: Frederic Breitwieser <frederic.breitwieser at xephic.dynip.com>
Date: Wed, 04 Mar 1998 19:55:11 -0500
Subject: Re: Crank Trigger Signal (was monitoring RPM)
>When I need speed information I buy a electronic bicycle speedometer
>for less than $10. Put the magnet on the wheel, mount the sender on
You know Bob - I laughed hysterically at how corny your idea was - but you
know what - it works, so more power to you!!! If everything was that
simple we'd be in good shape.
Too bad the electronic speedo for bikes doesn't have a serial port <Grin>
Frederic Breitwieser
Bridgeport, CT 06606
http://www.xephic.dynip.com/
1993 Supercharged Lincoln Continental
1989 4-Door Softtop Humvee (Hummer)
2000 Buick GTP (Mid-engine track car)
- ---
------------------------------
From: "Matthew B. Watts" <mwatts at facility.cs.utah.edu>
Date: Wed, 4 Mar 1998 19:44:23 -0600
Subject: Re: signal from coil and back emf......
- -----Original Message-----
From: Sandy <sganz at wgn.net>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
Date: Wednesday, March 04, 1998 6:00 PM
Subject: Re: signal from coil and back emf......
>I'm not exactly sure of your setup, but I guess that you are using the
>points or something similar to trigger the 555. EMF will be a problem, the
>kick back can be upwards of 400volts. What you want to do is something
>similar to a tach input, attach a resistor, and use the zener/tvs to clamp
>the voltage. You may also need a small cap to eliminate some noise. I'm not
>sure where but you can find a simple circuit in some magazines or
>electronic sites that have digital tachs and they should have a sample
>circuit.
You'll definitely need a clamping diode between a home-built driver
and any inductive load to suppress kick-back. For an injector or even
an ignition coil, I'd recommend a 1N5408 silicon rectifier diode. It's
a 32 cent part that you can connect between the driver output and
ground; it will save you a lot of grief. The striped side (cathode)
hooks to your output to provide a current path for the inductor to
discharge once the output signal is dropped. You should try to get
the diode as close as you can to the injector to keep the current
snap during discharge from causing any false triggering in your
circuit.
Hope this helps...
Matt Watts
University of Utah
Formula SAE Racing
_________________
------------------------------
From: Jason Greene <verde1 at us.ibm.com>
Date: Wed, 4 Mar 1998 21:19:45 -0500
Subject: EFI and Mileage
First, thanx for all the replies.
I'll cover all in one post as not to take up bandwidth.
The O2 and water temp sensors are new. The donor car didn't have an EGR
valve.
The ECU is from a 2.0L and the airflow meter and injectors are from a
2.2L.
Would this make that much of a difference??? BUT the pressure regulator IS
from
a 1.8 L. I thought that they were all the same. It keeps the pressure at 38
psi (I think). The fuel lines are all metal so no leaks, plus I don't smell
fuel at all. I used to smell it when I ran the carbs. Last time I checked
the
injectors were fine. I drove from Oregon to North Carolina 3 months ago
and
the milage was around 17 mpg. I'll check them again this weekend.
The air temp sensor is in the air flow meter. I haven't checked it but I've
read that is does very little fuel adjustment.
I've tried AFMs from various size engines with no improvement. It is either
too
rich (black plugs) or too lean (constantly back firing and power is reduced)
and the MPG is still very poor.
I'll check the archives to night.
Thanx again for the help,
Jason G.
------------------------------
From: Clare Snyder <snyder at snyder.on.ca>
Date: Wed, 04 Mar 1998 21:37:01 -0500
Subject: Re: signal from coil and back emf......
Sandy wrote:
>
> I'm not exactly sure of your setup, but I guess that you are using the
> points or something similar to trigger the 555. EMF will be a problem, the
> kick back can be upwards of 400volts. What you want to do is something
> similar to a tach input, attach a resistor, and use the zener/tvs to clamp
> the voltage. You may also need a small cap to eliminate some noise. I'm
not
> sure where but you can find a simple circuit in some magazines or
> electronic sites that have digital tachs and they should have a sample
> circuit.
>
> Sandy
>
> At 11:44 AM 3/5/98 +1300, you wrote:
> >Hi All
> >
> >I'm using a 555 timer set up as a one shot firing an injector. To trigger
> it I want to
> >use the negative of the coil. The circuit works great on the bench
> >but the once I connect it it fries the input.... I think this is
> >because of the back emf from the coil so I put a 12v zener across the
> >input.
> >Can anyone help me with a filter/clipper to stop this.
> >
> >Cheers
> >
> >Simon
> >++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > Simon Quested (E-mail questeds at lincoln.ac.nz)
> > Computer Technician, Silicon Graphics & Windows NT Support
> > Centre for Computing and Biometrics
> > LINCOLN UNIVERSITY OF NEW ZEALAND
> > Phone (64)(03) 3252811 Ext. 8087
> >++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >http://www.lincoln.ac.nz/ccb/techs/simon/default.htm
> >++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >I drive way too fast to worry about cholesterol
> >++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >
> >
Do like on a Bosch D-Jet - use a second set of points to trigger the
EFI. Either that or use a pulse transformer or a high value resistor and
a 5 volt zener to clamp the signal. Might just want to install 2, back
to back, to clamp the negative ring as well.
- --
_/\_
--|-----([])-----|--
S 0/ \0 B
Alls well that ends well!! www.snyder.on.ca is back
E-Mail service is back to normal
To avoid bouncing E-Mail messages
Reply to Clare at snyder.on.ca
OR
Remove the R from clsnyder in my E-Mail Address to reply. Stop the
spammers!!!
It's hard to soar like an eagle when your stuck with a bunch of
Turkeys!!!
------------------------------
From: Clare Snyder <snyder at snyder.on.ca>
Date: Wed, 04 Mar 1998 21:47:47 -0500
Subject: Re: signal from coil and back emf......
Matthew B. Watts wrote:
>
> -----Original Message-----
> From: Sandy <sganz at wgn.net>
> To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>
> Date: Wednesday, March 04, 1998 6:00 PM
> Subject: Re: signal from coil and back emf......
>
> >I'm not exactly sure of your setup, but I guess that you are using the
> >points or something similar to trigger the 555. EMF will be a problem,
the
> >kick back can be upwards of 400volts. What you want to do is something
> >similar to a tach input, attach a resistor, and use the zener/tvs to
clamp
> >the voltage. You may also need a small cap to eliminate some noise. I'm
not
> >sure where but you can find a simple circuit in some magazines or
> >electronic sites that have digital tachs and they should have a sample
> >circuit.
>
> You'll definitely need a clamping diode between a home-built driver
> and any inductive load to suppress kick-back. For an injector or even
> an ignition coil, I'd recommend a 1N5408 silicon rectifier diode. It's
> a 32 cent part that you can connect between the driver output and
> ground; it will save you a lot of grief. The striped side (cathode)
> hooks to your output to provide a current path for the inductor to
> discharge once the output signal is dropped. You should try to get
> the diode as close as you can to the injector to keep the current
> snap during discharge from causing any false triggering in your
> circuit.
>
> Hope this helps...
>
> Matt Watts
> University of Utah
> Formula SAE Racing
> _________________
I think you guys are reading this all wrong - he is popping his INPUT
from what I read. This is due exclusively to the fact that the primary
of the ignition system does NOT run on 12 volts, but something closer to
400 volts due to the self generated EMF in the coil - look at a coil
primary trace on a scope sometime. It is this that is popping the 555.
Just clamping it will definitely solve the problem - the engine will not
fire. You MUST use a high value resistor - something in the order of
470K should do the job, to limit the current, then a varister or zener
rated somewhere about 5 volts to keep the trigger voltage low enough it
will not blow holes through the junctions in the 555. You could use up
to 12 volts with a 555c. The coil back-emf from a 2 ohm injector is
negligible - I would use the low impedence units with a limitting
resistor to start with, then go to a peak and hold driver if necessary.
just my $.02 worth - and .02 of a $.70 dollat at that!!
- --
_/\_
--|-----([])-----|--
S 0/ \0 B
Alls well that ends well!! www.snyder.on.ca is back
E-Mail service is back to normal
To avoid bouncing E-Mail messages
Reply to Clare at snyder.on.ca
OR
Remove the R from clsnyder in my E-Mail Address to reply. Stop the
spammers!!!
It's hard to soar like an eagle when your stuck with a bunch of
Turkeys!!!
------------------------------
From: "Bruce Plecan" <nacelp at bright.net>
Date: Wed, 4 Mar 1998 21:40:16 -0500
Subject: Re: Crank Trigger Signal (was monitoring RPM)
ref Christopher Bruno:
Can't get away with a dam thing around here, actually it was a test(?)
ya right.
Bruce Admitted Cone Shaped Hat wearer
------------------------------
From: "Dave J. Andruczyk" <dave at scarlet.buffalostate.edu>
Date: Wed, 4 Mar 1998 22:29:56 -0500 (EST)
Subject: Re: signal from coil and back emf......
> Simon
> Two answers to the question put a zener across the collector to the
> emitter pick a zener at ~14v or a bit higher to snub cemf across the
> xsistor or a diode across the coil is ok but it slows down the injector
> because of circulating current through the diode.
> Simon Quested wrote:
also may need a beefy diode due to the current spike tht will be present.
?( use a diode that can handle several amps surge.) the best snubber i've
seen uses a zener and a regular diode across the collector emitter
juntion, the larger zener drop helps to speed up fall time, but requires
a transistor that can higher reverse voltages ( due to the fact that the
zener won't conduct until a higher voltage..)
dave
------------------------------
From: Simon Quested <questeds at whio.lincoln.ac.nz>
Date: Thu, 05 Mar 1998 16:25:18 +1300
Subject: Re: signal from coil and back emf......
Hi Matt
> You'll definitely need a clamping diode between a home-built driver
> and any inductive load to suppress kick-back. For an injector or even
> an ignition coil, I'd recommend a 1N5408 silicon rectifier diode.
I'm using a 1N5404....
> You should try to get
> the diode as close as you can to the injector to keep the current
> snap during discharge from causing any false triggering in your
> circuit.
I didn't know that ! but as it turns out the diode is across the
wires that go to the injector
Thanks for the help
Simon
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Simon Quested (E-mail questeds at lincoln.ac.nz)
Computer Technician, Silicon Graphics & Windows NT Support
Centre for Computing and Biometrics
LINCOLN UNIVERSITY OF NEW ZEALAND
Phone (64)(03) 3252811 Ext. 8087
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
http://www.lincoln.ac.nz/ccb/techs/simon/default.htm
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
I drive way too fast to worry about cholesterol
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------
From: Simon Quested <questeds at whio.lincoln.ac.nz>
Date: Thu, 05 Mar 1998 16:36:51 +1300
Subject: Re: signal from coil and back emf......
Hi All
> I think you guys are reading this all wrong - he is popping his INPUT
> from what I read.
Yep
> This is due exclusively to the fact that the primary
> of the ignition system does NOT run on 12 volts, but something closer to
> 400 volts due to the self generated EMF in the coil
Thats what I guessed the problem is.....
> You MUST use a high value resistor
Duh!!! Here's the solution I think.....I only have the zener
> - something in the order of
> 470K should do the job, to limit the current, then a varister or zener
> rated somewhere about 5 volts to keep the trigger voltage low enough it
> will not blow holes through the junctions in the 555. You could use up
> to 12 volts with a 555c.
I'm using a 555c and a 12v zener
> The coil back-emf from a 2 ohm injector is
> negligible - I would use the low impedence units with a limitting
> resistor to start with, then go to a peak and hold driver if necessary.
That's what I'm doing....
> just my $.02 worth - and .02 of a $.70 dollat at that!!
The cheque is in the mail ;-)
Thanks guys for all the help.
Simon
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Simon Quested (E-mail questeds at lincoln.ac.nz)
Computer Technician, Silicon Graphics & Windows NT Support
Centre for Computing and Biometrics
LINCOLN UNIVERSITY OF NEW ZEALAND
Phone (64)(03) 3252811 Ext. 8087
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
http://www.lincoln.ac.nz/ccb/techs/simon/default.htm
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
I drive way too fast to worry about cholesterol
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
------------------------------
From: Andris Skulte <askulte at emerald.tufts.edu>
Date: Wed, 04 Mar 1998 23:09:57 -0500
Subject: Re: VSS and freq converter circuit
> You could try 8 pin PIC micro, 5 volt regulator with capacitor,
> resistor on input pin, the VSS buffer should accept 5 volt logic.
> total part cost with rad shack board should be under $5.00.
> with 2 wires to rs232 port you could calibrate speedo.
> alex
Is this the same thing as the $35 PBASIC PS1-IC stamp my advisor was
telling me about? It seems ideal to me... What is the $5 chip you
mentioned, and how do I go about buying it, programming it, etc... I'm
just another ME trying some electrical stuff! :)
Andris
------------------------------
From: "Tony Bryant" <Tony.Bryant at psc.fp.co.nz>
Date: Thu, 5 Mar 1998 17:27:53 +1200
Subject: Re: signal from coil and back emf......
<snip>
> to 12 volts with a 555c. The coil back-emf from a 2 ohm injector is
> negligible - I would use the low impedence units with a limitting
> resistor to start with, then go to a peak and hold driver if necessary.
>
The back emf of injectors is only limited by the zener in the driver
- - generally a 39V zener (see the LM1949 docs). This back-EMF is vital
in allowing the injector to close fast.
More than enough to pop a cmos gate.
------------------------------
From: "David" <david at gardener.com>
Date: Wed, 4 Mar 1998 23:43:03 -0600
Subject: Re: Reference Book
Fred,
I only copied portions of the book.
Chapter 7 is titled
General Motors
Multiport Fuel Injection 1984-1985
Chapter 8 is titled
General Motors
Buick Sequential Fuel Injection 1984-1985
I presently have a 4.1 L in a 1970 MB 280SE. My current task is to complete
the body restoration and take control of the rust. Then a repaint.
Next will come the FI conversion.
I would really like to hear how you progress on your conversion.
David
- -----Original Message-----
From: Frederic Breitwieser <frederic.breitwieser at xephic.dynip.com>
To: diy_efi at efi332.eng.ohio-state.edu <diy_efi at efi332.eng.ohio-state.edu>;
DIY_EFI at efi332.eng.ohio-state.edu <DIY_EFI at efi332.eng.ohio-state.edu>
Date: Wednesday, March 04, 1998 9:52 AM
Subject: Re: Reference Book
|>I have a book called "Domestic Electronic Fuel Injection and Computer
|>Systems." The author is Frederick D. Allen. It was published by Prentice
|>Hall.
|>
|>I only have a couple of chapters copied. It was borrowed from the
library.
|>I was specifically interested in converting a 4 BBL carb 4.1 L Buick V-6
to
|>Fuel Injection. The text was the best I came across so far.
|
|Well David, I will be buying that book - because I'm converting a 2bbl 4.1L
|Buick V6 to EFI, and have bene struggling with all the details for a while
:)
|
|BTW, you didn't happen to notice if they slopped on a Holley Projection, or
|did something a little more challenging - such as independant injectors per
|cyl?
|
|Thanks,
|
|
|Frederic Breitwieser
|Bridgeport, CT 06606
|
|Homebrew Automotive Website:
|http://www.xephic.dynip.com/
|
------------------------------
From: Clare Snyder <snyder at snyder.on.ca>
Date: Thu, 05 Mar 1998 01:35:53 -0500
Subject: Re: signal from coil and back emf......
Tony Bryant wrote:
>
> <snip>
>
> > to 12 volts with a 555c. The coil back-emf from a 2 ohm injector is
> > negligible - I would use the low impedence units with a limitting
> > resistor to start with, then go to a peak and hold driver if necessary.
> >
>
> The back emf of injectors is only limited by the zener in the driver
> - generally a 39V zener (see the LM1949 docs). This back-EMF is vital
> in allowing the injector to close fast.
>
> More than enough to pop a cmos gate.
>
>
But not nearly as fierce as the back emf of a 12 ohm injector!!!
- --
_/\_
--|-----([])-----|--
S 0/ \0 B
Alls well that ends well!! www.snyder.on.ca is back
E-Mail service is back to normal
To avoid bouncing E-Mail messages
Reply to Clare at snyder.on.ca
OR
Remove the R from clsnyder in my E-Mail Address to reply. Stop the
spammers!!!
It's hard to soar like an eagle when your stuck with a bunch of
Turkeys!!!
------------------------------
From: T Hergen <thergen at svn.net>
Date: Wed, 4 Mar 1998 23:00:43 -0800 (PST)
Subject: Re: signal from coil and back emf......
Simon,
filtered +12 ---/\/\/\----------|
r2 |
points---/\/\/\----o----| |-----o-----pin2 of 555
r1 | c1 |
-----|\|----| |
| |/| |
| z1 |
o------------/\/\/\------|
| r3
gnd
r1: 1k
r2: 5k
r3: 5k
c1: 0.1uF
d1: 1n5231 (5v zener)
A circuit I saw for a 555 tachometer had the
circuit shown (view with fixed font). In any case,
try to avoid taking the 12v for your circuit from
the 12v terminal on the coil.
Tom
Standard disclaimer, use at your own risk etc....
On Thu, 5 Mar 1998, Simon Quested wrote:
> Hi All
>
> I'm using a 555 timer set up as a one shot firing an injector. To trigger
it I want to
> use the negative of the coil. The circuit works great on the bench
> but the once I connect it it fries the input.... I think this is
> because of the back emf from the coil so I put a 12v zener across the
> input.
> Can anyone help me with a filter/clipper to stop this.
>
> Cheers
>
> Simon
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> Simon Quested (E-mail questeds at lincoln.ac.nz)
> Computer Technician, Silicon Graphics & Windows NT Support
> Centre for Computing and Biometrics
> LINCOLN UNIVERSITY OF NEW ZEALAND
> Phone (64)(03) 3252811 Ext. 8087
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> http://www.lincoln.ac.nz/ccb/techs/simon/default.htm
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> I drive way too fast to worry about cholesterol
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
------------------------------
End of DIY_EFI Digest V3 #79
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