DIY_EFI Digest Tuesday, 16 April 1996 Volume 01 : Number 111 In this issue: Re: Ignition questions & the Nat semi Injector driver Re: DIY_EFI Digest V1 #110 Re: 745 Re: EEC-IV Questions Speed Density SFI -possible? Re: Ignition questions Re: Speed Density SFI -possible? HEI vs CDI Re: Ignition questions & the Nat semi Injector driver Re: Outboard Motor Coils Re: O2 sensor Nasties zapping our electronics Re: Ignition questions & the Nat semi Injector driver Re: Heywood ref, Surface gap plugs Re: Speed Density SFI -possible? Re: Speed Density SFI -possible? Re: Ignition questions & the Nat semi Injector driver Batteries Re: type of eprom Re: Heywood ref, Surface gap plugs Re: type of eprom Re: Ignition questions & the Nat semi Injector driver See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: arthurok@xxx.com (ARTHUR OKUN ) Date: Mon, 15 Apr 1996 02:39:57 -0700 Subject: Re: Ignition questions & the Nat semi Injector driver you can make a low ohms resistor using copper wire just find a wire resistance table and cut a length of wire for the resistance you need ive done this to make low ohms current shunts . you can use 1 or 2 watt carbon high value resistors for forms if the wire will fit on it. ------------------------------ From: talltom Date: Mon, 15 Apr 1996 03:49:40 -0700 (PDT) Subject: Re: DIY_EFI Digest V1 #110 - --------------------------- > >From: Hoa T Nguyen >Date: Mon, 15 Apr 1996 01:07:38 -0700 (PDT) >Subject: Just a note... > >Thanks much to all for the Heywood references. I place my order tomorrow. > >Saab has been using individual coils per cylinder for quite a while. The >Trionic engine management system has the ability to monitor the current >flow through the coils, thus to the plug, to analize the combustion >quality. The system can then make changes to the spark / fuel on a >cylinder by cylinder basis. Basicly the same stuff being discussed on the >332 list. Saab did a neat demo where they pumped exhaust from an old >two-stroke car into the new 900 turbo (I think) where it was again used. >The cool part was it came out cleaner than it went in. What is the 332 list? subscription address? Engineers replaced the standard plug with a single isolated >electrode then built up a special piston with a peak in the middle. The >peak acts as the ground, causing a spark to jump across the combustion >chamber. By changing timing they can change the effective plug gap as >well. Sounds like the best plug to date. > >Thanks again to everyone else for the interest >- - Mike Kent The idea is unique, but I'm curious about the transfer of material between piston/ring/cylinder bore/crank/bearings? > >------------------------------ ------------------------------ From: talltom Date: Mon, 15 Apr 1996 03:49:38 -0700 (PDT) Subject: Re: 745 > >Hello everyone... I'm new to this list, so I hope this isn't off-topic. > I am modifying my '81 BMW 745i (factory intercooled turbo, L-Jetronic >injection without an 02 sensor). Stock was 252 hp with the original 3.2 >liter 6 cyl, and 7 psi boost. Are you sure? one of my customers has one of these and it has the o2 sensor, admittedly you have to be undernearth the thing to find it, but it's there. ------------------------------ From: ehernan3@xxx.com (Edward Hernandez (R)) Date: Mon, 15 Apr 1996 08:46:14 +0500 Subject: Re: EEC-IV Questions "Mind you, it has been 16 months now, it's all getting a bit hazy." No, no, you've got it exactly right. Failure Mode Effects Management. It's been couple years for me, but that's exactly what I did and how I did it. I was surprised how well it worked, too. In fact, we had some discussion over how transparent the failure mode was and if we should rough it up so the customer knew something was wrong! What's bugging me is that I did that over the winter, then I was transferred. I wonder how well it works when the weather is hotter. Anyone out there with a Mark VIII want to pull their MAS connector and give me some constructive criticism? :) ------------------------------ From: orlin steven jared Date: Mon, 15 Apr 1996 09:54:30 -0400 (EDT) Subject: Speed Density SFI -possible? Hi All, I finally read some info on fuel injection systems (the basics) in the March issue of Car Craft, and I have a question. It seems that only MAF based systems use sequential port injection, and the speed density systems use batch fire injection. At least, that's the way the article makes it look. I was wondering what the reason for this is, and if you can make up a system (without much difficulty) for SFI with a speed density system. For my future project (fuel injected BBC, homemade manifold), it seems that a speed density system would be the best choice, but SFI instead of batch fire would also seem to be an added bonus. BTW, has anyone compiled information on tunability of S-D systems? I couldn't find anything on the web page. Thanks, Steve ------------------------------ From: Fred Miranda Date: Mon, 15 Apr 1996 07:33:38 GMT Subject: Re: Ignition questions Jim If I remember correcty, primary flyback voltage is a reflection of secondary induced voltage, so I would think that limiting primary flyback to 60v would seriously limit potential spark voltage. Of course the best way to learn about this would be to try what you have, see how it performs then try something different. As for the balasting, my original post wasn't to suggest you use it, only to illistrate how something simple could work. Instead of the ballast, why not measure coil charge time and then give it that + a little extra dwell time, since you are doing the whole thing from scratch anyway. Fred >About the tip 120, I've got a good supply. (Radio shack 1 mile away) It also >carries internal protection for reverse voltage and high voltage (It's only 60V >max), of course I maybe able to slide by on luck and a handfull in case I blow >one! > > Jim Staff > > ------------------------------ From: Fred Miranda Date: Mon, 15 Apr 1996 07:48:01 GMT Subject: Re: Speed Density SFI -possible? Steve Several aftermarket efi systems do sequential + speed density. The ones I know of are: Autronic DFI Electomotive (the only one I know of that does MAF) Motec and I am sure, others. As for speed density tuneability, as long as the engine pulls decent vacuum, you should be ok. The more peaks and valleys in it's volumetric efficiency the more resolution you will need in your tables. I think Electomotive is the most limited while Autronic and Motec are the best in this respect. >I finally read some info on fuel injection systems (the basics) >in the March issue of Car Craft, and I have a question. > >It seems that only MAF based systems use sequential port injection, >and the speed density systems use batch fire injection. >BTW, has anyone compiled information on tunability of S-D systems? >I couldn't find anything on the web page. ------------------------------ From: MSargent@xxx. Sargent) Date: Mon, 15 Apr 1996 12:31:23 -0400 Subject: HEI vs CDI Why is everyone building a conventional points replacement ignition circuit rather than a capacative discharge ignition? My experience says that CDI (MSD-6M) is FAR superior to inductive discharge (points). If we are going so far as to build a complete engine management system, why are we making such a large concession in performance? Mike +--------------------------------------------------------------------------+ | Michael F. Sargent | Net: msargent@xxx.com | Phone: 1(613)721-0902 | | Gallium Software Inc.| | FAX: 1(613)721-1278 | +--------------------------------------------------------------------------+ ------------------------------ From: John S Gwynne Date: Mon, 15 Apr 96 12:44:25 -0400 Subject: Re: Ignition questions & the Nat semi Injector driver - -------- In message <199604140544.FAA25983@xxx.us> , you write: | 2nd, could I use this driver to control a ignition circuit? | | 3. What is a good design for an electronic igniton system. Particularly h | ow | do I stop the Back EMF from blowing everything apart after ignition? I though | | about placing several (4) tip120 darlingtons to switch the current, and then | a Jim, this is the proto circuit I used to evaluate the LM1949 with a Harris HGTP14N40F3VL (this part clamps the primary at 400V) for the efi332 project. It duplicates the data I collected from a Buick 3.1L V6 w/ DIS. lm1949 pin 1 : input pin 2 : IGBT gate pin 3 : 0.0022uF : 82k : IGBT gate pin 4 : 68 / 1.2k voltage divider to 0.147 sense resistor pin 5 : sense resistor ground pin 6 : +5VDC return pin 7 : +5VDC pin 8 : 10k to pin +5VDC comments: - - The 0.147 ohm sense resistor was only what I had on hand. It needs to be more like 0.03 ohms to ensure Vgate is large enough. - - a small resistor should be added between pin 2 and the IGBT gate. - - The "trick" in using this (any) circuit is stabilizing the feed back loop as on pin 3. (The feedback loop limits the maximum current.) If you use a different transistor or significantly change the circuit, you will have alter the compensation for a stable well behaved transfer function. - - 3mH at 10A is 150mJ. I seem to recall a stun gun is like 25mJ, and 50mJ through the heart can be fatal. (Is that correct???) Anyways, becareful with the thing. :) Buick system data: coil: Buick 3.1L V6 w/ DIS primary: 0.344 Ohms DC (room temp.; @250mA) 3.00 mH open @ 1 kHz (wo/ compensation of DC resistance) 0.235 mH short @ 1 kHz secondary: 5.47 k Ohms DC 28.0 H open @ 1 kHz 4.5 H short @ 1 kHz forgot to measure the turns ratio..(from inductance measurement, it must be around 90-100). The primary current waveform was very well behaved. | | -------| | / | | / | | / | | / | | / | | / | | / | -------------------------- build time 2.75mS hold time 0.70 mS peak current 8.9A (note: measured sense resistor (copper) at 70 deg. F.; made the test at about 30 deg. F. Should compensate for temp. Actual value may be closer to 10A.) driver voltage: | | | |------- | | | | | | | | | --------- |---- -------------------------- rose to 2V during build time abruptly transitioned to 7.5V during the hold time. (other side of coil was about 14V w/ a voltage drop of 3V at the peak) John S Gwynne Gwynne.1@xxx.edu _______________________________________________________________________________ T h e O h i o - S t a t e U n i v e r s i t y ElectroScience Laboratory, 1320 Kinnear Road, Columbus, Ohio 43212, USA Telephone: (614) 292-7981 * Fax: (614) 292-7297 - ------------------------------------------------------------------------------- ------------------------------ From: gtk110@xxx.edu Date: Mon, 15 Apr 1996 17:16:55 GMT Subject: Re: Outboard Motor Coils > > > Bruno. (u933234@xxx.au) > > "A sewer rat might taste like pumpkin pie, but I wouldn't know cos I > don't eat the filthy muthaf***a" > Pulp Fiction, eh OK "Say what again, I dare ya, I double dare ya muthaf***a" and "Baby, I had to crash that Honda" "Gripping the wheel, his knuckles went white with desire...the wheels of his Mustang exploding on the highway like a slug from a .45... True death... 400 horsepower, maximum performance piercing the night... This is BLACK SUNSHINE!" ------------------------------ From: gtk110@xxx.edu Date: Mon, 15 Apr 1996 17:29:04 GMT Subject: Re: O2 sensor I'd just like to thank the people for helping me out with the o2 sensor thing. I got the Lm3914 from national semi for nothing (actually 3 of them), and the LED's, resistors, project box, and board at Radio shack for about $10...sure beats Edelbrock's (I think, my friend has one) at the tune of $40-$50. If I had the Edelbrock box, mine would look exactly the same...It even performs the same way, which brings up a question: Is there any way to avoid the scanning effect this thing does. I used the second listing of the O2 sensor under the DIY_EFI Projects listing on the net....instead of trimmers, I used the 2.2kOhm resistors, and 5mm LED's....no capacitor Thanks a lot guys! Gannon "Gripping the wheel, his knuckles went white with desire...the wheels of his Mustang exploding on the highway like a slug from a .45... True death... 400 horsepower, maximum performance piercing the night... This is BLACK SUNSHINE!" ------------------------------ From: jsturs@xxx.nl (Jim Sturcbecher) Date: Mon, 15 Apr 1996 21:28:18 -0100 Subject: Nasties zapping our electronics I am posting this again since I didn't see it echo. Sorry if anyone has already received it. Since there has been some discussion recently about protecting the electronics against back emfs and other nastires I thought I would bring your attention to 3 application notes I found recently from SGS-Thomson. These are in PDF format (uses Adobe Acrobat to view and print). These ANs contain some interesting info about sources and types of signals that can not only give noise but also zap your carefully designed circuits unless you safeguard them. AN553/1292 - Protection Standards Applicable to Automobiles AN554/0393 - Choice of Protection in Automotive Applications AN555/0393 - Automotive Protection with the RBOxx Series. the URL is: http://www.st.com/STonLINE/books/pdf/alpha/an/index.html I have no connection with SGS-Thomson, just found these notes whilst browsing for automotive electronics components. Later, Jim Sturcbecher jsturs@xxx.nl ------------------------------ From: cmorris@xxx.com (Charles) Date: Mon, 15 Apr 1996 14:42:45 -0700 Subject: Re: Ignition questions & the Nat semi Injector driver You wrote: > >you can make a low ohms resistor using copper wire just find a wire >resistance table and cut a length of wire for the resistance you need >ive done this to make low ohms current shunts . Me too. This is only accurate at relatively low current flows where the wire stays cool, though, because copper has a pretty high temperature coefficient! There's a reason they use nichrome and other strange alloys for power resistors... - -Charles ------------------------------ From: ehernan3@xxx.com (Edward Hernandez (R)) Date: Thu, 11 Apr 1996 12:30:47 +0500 Subject: Re: Heywood ref, Surface gap plugs "I believe Heywood consults regularly with Ford (so I've heard)" Yes, he does, about once a quarter. Others have already posted the correct ISBN(glad to see how popular the book is). To the guy who described his 2S Mercury spark plugs: Those sound like what I call surface gap plugs. I'd seen ads for them a long time ago, and I've heard they may be used in certain NASCAR teams. Mercury 2S motors are pretty high strung things with great specific output, but before swapping the plugs into a car, think about about the re- quirements of a boat motor vs a car motor, or rather, what does a plug have to do in a car that it doesn't have to do in a 2S boat motor? idle longer, very low throttle settings, more frequent transients... Maybe these plugs behave "colder" than normal plugs? ------------------------------ From: orlin steven jared Date: Mon, 15 Apr 1996 18:28:23 -0400 (EDT) Subject: Re: Speed Density SFI -possible? > Several aftermarket efi systems do sequential + speed density. > The ones I know of are: > Autronic > DFI > Electomotive (the only one I know of that does MAF) > Motec > and I am sure, others. > > As for speed density tuneability, as long as the engine pulls > decent vacuum, you should be ok. The more peaks and > valleys in it's volumetric efficiency the more resolution you > will need in your tables. I think Electomotive is the most limited > while Autronic and Motec are the best in this respect. Great. I'll have to write to them and see what they offer. What do you consider 'decent' vacuum? Also, what is usually tuneable with these systems? spark map, injector timing, opening time, etc. ? I'm a real novice :-) Steve ------------------------------ From: Fred Miranda Date: Mon, 15 Apr 1996 16:18:47 GMT Subject: Re: Speed Density SFI -possible? >Great. I'll have to write to them and see what they offer. What >do you consider 'decent' vacuum? Lets say: idles below 60kpa (12") and will cruise at resonable speeds below 70kpa (9"). The main idea is, the more vacuum the better as the system operates over a wider range and will deal with altitude changes better. >Also, what is usually tuneable with these systems? spark map, injector >timing, opening time, etc. ? I'm a real novice :-) Yes, and much more. The better systems will blow your mind. (Motec will also blow your wallet) Fred ------------------------------ From: William Sarkozy Date: Mon, 15 Apr 1996 19:12:29 -0700 Subject: Re: Ignition questions & the Nat semi Injector driver At 05:44 AM 4/14/96 GMT, you wrote: > General: When the field in the primary collapses (the +12V side of the coil) >there is a sudden induced voltage, duh... But is it true that the direction of >the voltage is the reverse of it's initial condition? Also these back conditions >can have voltages which can be of several hundered volts--if anyone has done >anything in this area don't be shy!!!!! I know that the stupid point system can >take it so why can't a transistor and some diodes? Sometimes its convenient to think of mechanically equivilant systems.....The inductance of the ignition coil ("L"...a physical constant based on geometry and phisical characteristics) is similar to mass (M) in a mechanical system. Current (I) is similar to velocity and voltage (V) is similar to force. Now then, when you have a mass moving at a finite velocity (a finite current passing through an inductor) and you attempt to abruptly stop that mass (the "brick wall" syndrome), what have you? You guessed it: a force proportional to the time rate of change of velocity (F=m*dv/dt). So it goes with an inductor: V=L*di/dt. The polarity requires a little thought. When you "push" on a mass to accelerate it, it resists. We tend to think of this resistance as a "positive" force, although it really makes no difference. What is important is that once the mass is moving and we attempt to slow it down, it wants to "pull" us along (negative or opposite of "push"). Again so it goes with the inductor.....when you first close the points (or turn on the transistor), the current through the primary of the coil rises over some finite time. When you open the points....wham...small dt, finite di, finite L all add up to a large voltage. Note that since the current is FALLING (rising in the negative direction), the voltage is opposite of that when the inductor is being charged. How do you manage those small displacement, large forces in a mechanical system? You add springs at strategic locations. So it goes with the electrical system (note the capacitor across the ignition points). It is similar to a spring between you and the mass in the mechanical system. Note that the spring can't be too "soft" (capacitor value too large) or you'll not get those high di/dt values which are responsible for the induced secondary voltage. You want high di/dt, but not so high that you destroy the driver circuits. All is a trade-off. This is a simple explanation. Modern CD (Capacitor Discharge) circuits add subtle refinements which lead to ultimate performance increases. There once was a book by Markus called ELECTRONIC CIRCUITS MANUAL which has a dozen or so ignition schematics. They're probably all out of date by now, but are always good for reference. E-mail me and I'll fax them to you if you like. Bill ------------------------------ From: dzorde@xxx.au Date: Tue, 16 Apr 96 08:51:06 Subject: Batteries I hope this is not too far off the subject of EFI, but I desperately need an address and fax number for Eagle Picher (they produce batteries). So if anyone happen to know, could you please mail it. Thanx in advance (I hope) Dan dzorde@xxx.au ------------------------------ From: pjwales@xxx.net (Peter Wales) Date: Mon, 15 Apr 1996 21:17:57 -0400 Subject: Re: type of eprom >It's from a fiesta Rs turbo '90 >Do you know the pinout? I've made this offer before and am happy to do it again. I will supply a decoder for any EECIV computer complete with a copy of the ORIGINAL software in a 27256 for $100. You can then do what you want with 27256's and just plug them into the adaptor which plugs into the "service" port on the back of the computer. I will also identify the full and part throttle fuelling and timing maps for you. I won't identify boost limits, speed limits rev limits etc as they cost me too much to develop. If you're interested, mail me. Peter Wales pjwales@xxx.net President Superchips Inc Chairman Superchips Ltd "Timing is everything" Superchips home page with all the answers http://www.superchips.com ------------------------------ From: orlin steven jared Date: Mon, 15 Apr 1996 21:29:28 -0400 (EDT) Subject: Re: Heywood ref, Surface gap plugs > To the guy who described his 2S Mercury spark plugs: Those sound like > what I call surface gap plugs. I'd seen ads for them a long time > ago, and I've heard they may be used in certain NASCAR teams. Mercury > 2S motors are pretty high strung things with great specific output, > but before swapping the plugs into a car, think about about the re- > quirements of a boat motor vs a car motor, or rather, what does a plug > have to do in a car that it doesn't have to do in a 2S boat motor? > idle longer, very low throttle settings, more frequent transients... > Maybe these plugs behave "colder" than normal plugs? Surface gap plugs are the coldest plugs you can get. On the rating engines at Autolite they can't even be made to pre-ignite. They would also foul out pretty quickly after a few cold starts in a street motor. Steve ------------------------------ From: pjwales@xxx.net (Peter Wales) Date: Mon, 15 Apr 1996 21:14:03 -0400 Subject: Re: type of eprom >It's from a fiesta Rs turbo '90 >Do you know the pinout? Yes :) Peter Wales pjwales@xxx.net President Superchips Inc Chairman Superchips Ltd "Timing is everything" Superchips home page with all the answers http://www.superchips.com ------------------------------ From: MTaylorfi@xxx.com Date: Tue, 16 Apr 1996 00:12:52 -0400 Subject: Re: Ignition questions & the Nat semi Injector driver I would appreciate that. I can be reached at (303) 934-7205 at 6 o'clock (Colorado time) Tuesday evening. My computer is my fax machine so fisrt call me (Mike Taylor) and I'll set it up. BTW nice second order differental equation explaination. Thanks!! See ya, Mike ------------------------------ End of DIY_EFI Digest V1 #111 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. A non-digest (direct mail) version of this list is also available; to subscribe to that instead, replace "diy_efi-digest" in the command above with "diy_efi".