DIY_EFI Digest Tuesday, 8 October 1996 Volume 01 : Number 305 In this issue: Mounting Air Intake Temp Sensor? Ignition timing reference points RE: Mounting Air Intake Temp Sensor=?US-ASCII?Q?=3F?= RE: Mounting Air Intake Temp Sensor RE: Mounting Air Intake Temp Sensor RE: Using PC HW (& Ignition timing reference points) Re: Ignition timing reference points Re: FW: FW: DIY Traction Control? Re: MAP sensor, etc RE: Using PC HW (& Ignition timing reference points) Re: Ignition timing reference points Volume of fuel injected RE: 460 EEC-IV info FW: MAP sensor, etc Re: Using PC HW (& Ignition timing reference points) Re: Ignition timing reference points D Jet patents Boost retard Re: Volume of fuel injected Re: Volume of fuel injected Re: Ignition timing reference points RE: Using PC HW (& Ignition timing reference points) Re: Volume of fuel injected Re: Volume of fuel injected See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Jeremy Pronk Date: Tue, 8 Oct 1996 20:45:21 +1000 (EST) Subject: Mounting Air Intake Temp Sensor? Hi, I was just looking about the engine of my Alfa. I plan to removed the stock airbox housing, and replace it with "trumpets" bolted upto the weber throttle bodies. Now my question is, where should I re-mount the air intake temperator sensor? I mean I cant really tap it into one of the trumpets... regards, Jeremy, Sydney AUSTRALIA '83 AlfaSud Ti (Haltech E6 EFI) ------------------------------ From: Kalle Pihlajasaari Date: Tue, 8 Oct 1996 12:39:54 +0200 (sat) Subject: Ignition timing reference points Hi William and All, > From: William Boulton[SMTP:boultonw@xxx.au] > > Like to add 2cents to the debate. The best way (IMHO) to achieve any > degree of accuracy with timing prediction is to run as many reference > points per revolution as possible. I've see the result of 1/rev on a twin > and that was a disaster. Engines just do not maintain consistent angular > velocity during a revolution. I developed a simulator some time ago to > test theory on this and found that good results are obtained with at least > 6 reference points per rev. I tried a number of basic equations and > settled on a variation of the one Chaxel used. Just multiplied the result > by some large fraction just less than 1. Still easy in integer assembler. > The problem in predicting timing stems mostly from dA and not dV. I was thinking of adding a 256 or 360 slot optical interrupter disk into my distributor to give double the that number of edges every rev of the dizzy (or the same resolution on the crank). Is one degree on the crank accurate enough for a totally digital one or two of design for a mapped ignition. Interrupter disks like this are available alone and have usually got an index mark at another radius. I could then just replace the cam section with a nice shaft without the centrifugal advance (will the rotor still point close enough to the correct cap electrode if the rotor is not advanced at all and the timing is ? Just a few thoughts. Cheers - -- Kalle Pihlajasaari kalle@xxx.za Interface Products Box 15775, Doornfontein, 2028, South Africa +27 (11) 402-7750 Fax: +27 (11) 402-7751 ------------------------------ From: p.m.shackleton@xxx.uk (Paul Shackleton) Date: Tue, 08 Oct 1996 12:16:00 +0100 Subject: RE: Mounting Air Intake Temp Sensor=?US-ASCII?Q?=3F?= Can you describe what these throttle bodies look like? Are they standard = Alfa? Do they have an injector location, and are they one throttle butterfly= = per cylinder? I suppose what I am asking is could they be used as replacements for Weber = = DCOE sidedraught carbs to convert to EFi? Paul P.M.Shackleton@xxx.uk ---------- From: diy_efi To: diy_efi Subject: Mounting Air Intake Temp Sensor? Date: 08 October 1996 20:45 Hi, I was just looking about the engine of my Alfa. I plan to removed the stock airbox housing, and replace it with "trumpets" bolted upto the weber throttle bodies. Now my question is, where should I re-mount the air intake temperator = sensor? I mean I cant really tap it into one of the trumpets... regards, Jeremy, Sydney AUSTRALIA '83 AlfaSud Ti (Haltech E6 EFI) ------------------------------ From: Jeremy Pronk Date: Tue, 8 Oct 1996 22:24:37 +1000 (EST) Subject: RE: Mounting Air Intake Temp Sensor On Tue, 8 Oct 1996, Paul Shackleton wrote: > I suppose what I am asking is could they be used as replacements for > Weber DCOE sidedraught carbs to convert to EFi? I am not sure of all the different weber throttle body models, but the ones on my alfa are 45mm IDF throttle bodies, there is two of them. They are just in place of the stock 36mm IDF weber carbs. They are nearly exactly like the stock twin carbies, except they are bigger, and only have a butterfly and an injector mount. (ie the car has 4 throttle bodies). Does that answer your question? regards, Jeremy, Sydney AUSTRALIA '83 AlfaSud Ti (Haltech E6 EFI) ------------------------------ From: p.m.shackleton@xxx.uk (Paul Shackleton) Date: Tue, 08 Oct 1996 14:20:51 +0100 Subject: RE: Mounting Air Intake Temp Sensor Jeremy, Are these standard on an Alfasud? Paul Shackleton ---------- From: diy_efi To: diy_efi Subject: RE: Mounting Air Intake Temp Sensor Date: 08 October 1996 22:24 On Tue, 8 Oct 1996, Paul Shackleton wrote: > I suppose what I am asking is could they be used as replacements for > Weber DCOE sidedraught carbs to convert to EFi? I am not sure of all the different weber throttle body models, but the ones on my alfa are 45mm IDF throttle bodies, there is two of them. They are just in place of the stock 36mm IDF weber carbs. They are nearly exactly like the stock twin carbies, except they are bigger, and only have a butterfly and an injector mount. (ie the car has 4 throttle bodies).= Does that answer your question? regards, Jeremy, Sydney AUSTRALIA '83 AlfaSud Ti (Haltech E6 EFI) ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 8 Oct 1996 08:36:21 -0500 Subject: RE: Using PC HW (& Ignition timing reference points) Y'know, I've been reading with the greatest of anticipatory delight the posts on various efi schemes. But ... one thing keeps coming to my muddled mind (I've got old-timers disease). One of the 'cute' things about the original Apple that's sorta found its way down to the MAC is the mentality to save a few bucks by makin' the processor do all the work (used to have to scan the keyboard, be the disk controller, the video I/O, etc.) Saved money, didn't have to make any hardware changes, so was faster (as long as the processor could do it). Problem is, that it has disadvantages also. Processor is busier. Interrupt service routines become more impotent (no, not a slip'a da tongue). Timing becomes critical and an Al-Gore-ythm error can cause missed events. Back when I was a young tech (before monolithic op-amps), one watched their pennies. You didn't use too many transistors or zeners, etc as they cost money. Then along came the 709 op-amp. Quickly followed better versions and then the 741. One day I criticized a design that used an op-amp where a simple transistor would do, only to realize that the op-amp was less expensive and worked better. Pleez: what'm I trying to say? Am I mistaken, or do many of the posts here seem to want to make the cpu do everything? Take an A/D and read a noisy signal and let the software filter it (when a simple integrating lo-pass filter would save so much trouble -- and add, maybe, 32 cents to the cost). Or, try to do all the ignition timing via internal counters/timers and interrupts, when maybe a little PLL in the front end could process some of that and make the cpu / software task lots simpler. For example, I have a friend (who is a brilliant engineer), that designed a speed density system using blowers for racing jet skis. He didn't use a computer at all, but combined analog and digital techniques. He used a programmable up/down counter driven by a clock to produce the injector pulse. The counter was loaded with a number that corresponded to how long the injector stayed open, and was triggered by RPM. If that were used by a computer controlled system, that number would only be changed when the injector timing needed changing (and some filtering could spare lots of unnecessary changes due to slight variations). A similar system could be devised for ignition timing. Let a PLL take a few timing points from the crank or cam and produce any degree (pun) of resolution desired. Load a counter with the advance desired and let that peripheral circuit control the timing. Only change the advance when needed. Now, understand, I really haven't thought about perzactly how to do all these things. Just wondering if anyone else has. It is my experience that being too much the purist (i.e. a hacker / fanatic trying to make the confuser doo it all) puts you way up on the diminishing returns curve, when the most expeditious (isn't that a new Ford product?) approach would seem to be to use any and all tricks to get what we want. [Now, if what you want is to play wid da cornfuser, so be it. As I've said before, I wanna D-R-I-V-E !] Tom Cloud ------------------------------ From: Stephen Dubovsky Date: Tue, 8 Oct 1996 11:41:09 -0400 Subject: Re: Ignition timing reference points >I was thinking of adding a 256 or 360 slot optical interrupter disk into >my distributor to give double the that number of edges every rev ... The only problem I see w/ this is dirt. The guys in the motor industry very rarely use optical encoders because you get a few specs of dust on the encoder wheel and things go crazy. They almost always prefer some sort of magnetic/hall sensor type pickup or use a resolver (and then a resolver to digital converter) if higher accuracy is required. If your interested and dont know what a resolver is, I can type up some sort of "short" explanation;) Both of these methods are relatively insensitive to dirt and grime (unless its a ferrous material...) Hope this helps... SMD ------------------------------ From: Stephen Dubovsky Date: Tue, 8 Oct 1996 11:41:10 -0400 Subject: Re: FW: FW: DIY Traction Control? > I know dropping random cylinders is the way used to limit RPM and > regain traction, etc. But I dread everytime I hit the rev limiter in > the Chev, it feels like someone is trying to tear the engine out from > under the bonnet. And there is a similar feeling in the newer sports > cars (ie. relatively powerful cars). Is this normal ?? The revlimiter in my 83 911 doesn't seem to have this 'problem'. I believe it pulls spark (but not fuel) and does not sound terrible when Im against it. My FZR600 motorcycle pulls spark and it doesn't sound bad either (sort of like a lean misfire) although its tough to tell when it comes in at 11500 rpm (engine is sort of loud at that point;) It mostly feels like you hit a brick wall; your hanging on for dear life and all of a sudden your acceleration goes to zero. Kinda wants to throw you over the handlebars;) You try not to use it too often;) SMD ------------------------------ From: Todd King Date: Tue, 08 Oct 96 08:36:00 PDT Subject: Re: MAP sensor, etc <<< From: "Chuck Thigpen" Date: Mon, 7 Oct 1996 07:37:05 +0000 Subject: Air Pressure Transducer Does anyone know of a source for a fairly low cost Air Pressure Transducer that measures positive and negative gauge pressure? It doesn't have to measure extreme pressures. I'm looking for a transducer that will measure boost pressures of up to 30 psi and vacuum down to - 14.7 psi. It would also be helpful if the transducer was linear in measurement. Any help on any transducers>>> The GM 3 bar MAP sensor is about $50 from the "discount" GM parts dealers; I use it to log boost on the turbo Regal. Call 'em up, order one and you're good to go! <<>> We have a test facility called HALT (Highly Accelerated Lifecycle Testing) that shakes, heats, freezes, etc the system boards until failure is observed. The operator I speak with often expresses his amazement at how far the boards have to be pushed before failure occurs. Oscillatory excursions of several inches p-p for a board with add-in cpu cards, mem card (and IDE, SCSI connecters) hanging on for dear life is not uncommon. <<< So all these autos in the films is fairly accurate then... what do you guys out there in DIY EFI land prefer? (Manual or automatic transmission) >>> Well for turbo apps the automatic is a better choice (IMO) for full throttle acceleration, at least for keeping the turbo singing happily along during the shifts... Todd Todd_King@xxx.com ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 8 Oct 1996 10:46:09 -0500 Subject: RE: Using PC HW (& Ignition timing reference points) I received this response: >Hi Tom. > >On Tue, 8 Oct 1996, you wrote: >> Y'know, I've been reading with the greatest of anticipatory delight >> the posts on various efi schemes. But ... one thing keeps coming to >> my muddled mind (I've got old-timers disease). > >Ditto. > >> a programmable up/down counter driven by a clock to produce the injector >> pulse. The counter was loaded with a number that corresponded to how >> long the injector stayed open, and was triggered by RPM. If that >> were used by a computer controlled system, that number would only be >> changed when the injector timing needed changing (and some filtering >> could spare lots of unnecessary changes due to slight variations). >> >> A similar system could be devised for ignition timing. Let a PLL take >> a few timing points from the crank or cam and produce any degree (pun) >> of resolution desired. Load a counter with the advance desired and let >> that peripheral circuit control the timing. Only change the advance >> when needed. > >That's more like what I had envisioned also. The list majority seems to >be dead set that a Motorola CPU is the way to go, but I'm much in favor >of simple stupid hardware solution which is tweaked by a computer (PC?). >I'm preparing to buy a Data Acquistion & Control board (for research >and prototyping mainly) any day now. The other half of the design would >be similar to the system your friend designed but I don't know enough >about PLCs, PLLs (?), and PICs to make a good decision about which would >be better for that application. Can you give me any more insight >about the hardware he used to drive the injectors? > >BTW--I'd be glad to share my experiences/ideas offline until I get >something going. Many of the DIY_EFI Motorola guys are working on real >projects and I'm not going to interject my stupidity until I feel better >about proving my thoughts with a running motor. Could be the wrong >attitude, but then again...I'm just tinkering with very little time >and even less money. > >Thanks, to which I respondeth backeth: I think your thoughts would be very beneficial to the group -- I wish you'd re-post this to diy_efi. There's many on the list that feel just like you, and discussion can't occur if people don't do it or do it out of the group. I think what you've said is very relevant and would be of interest to the majority -- not the minority. [Actually, I'm gonna post it -- just won't use your name, okay?] As far as what my friend used? Dunno. I can ask him again, but he's moved on and has forgotten. He says that there are drivers available, but seems t'me a simple BJT or MOS transistor is adequate. Now, if you're trying to pulse the injector hard (with a 'high' current) and then holding it on with a lower current, that might take a little more thought (though, a capacitor can deliver the pulse). So, I'm green too. Maybe know more than some about a few things and definitely know less about others. Flame on the person that makes you feel bad 'cause you ask a 'dumb' question. Time honored 'dumb' question: "Why is the sky blue?" answer: Clearly that's a two part question. ... "Why?" Well, we'd all like to know that. And "Is the sky blue". Yes. Tom Cloud ------------------------------ From: M HILL Date: Tue, 8 Oct 1996 17:01:59 GMT0BST Subject: Re: Ignition timing reference points > From: Kalle Pihlajasaari > > I was thinking of adding a 256 or 360 slot optical interrupter disk into > my distributor to give double the that number of edges every rev > of the dizzy (or the same resolution on the crank). Is one degree > on the crank accurate enough for a totally digital one or two of > design for a mapped ignition. Interrupter disks like this are > available alone and have usually got an index mark at another > radius. I could then just replace the cam section with a nice > shaft without the centrifugal advance (will the rotor still point > close enough to the correct cap electrode if the rotor is not > advanced at all and the timing is ? > > Just a few thoughts. This is far more than enough for a digital system. Most systems these days use a 36 tooth wheel with one tooth missing to signify TDC. With the computer it is possible to get accurate enough timing form this. 360 teeth would provide so much information you would need a faster processor to keep up. Martin ------------------------------ From: Jason Walters Date: Tue, 08 Oct 1996 09:21:07 -0700 Subject: Volume of fuel injected I=92m most definitely not up to the level of expertise of this group, but I don=92t know where else to field my question. Here=92s my problem. I=92m trying to calculate the volume per burst for = a typical fuel injector. I=92ve downloaded some specifications, but I=92m = at a loss to break them down. If a given fuel injector has a flow off 150 cc/min, how many bursts/firings are we talking per 60 second interval? Is that a measurement with the injector wide open for 60 seconds, or is that a measurement for something like 50 bursts with a duration of 15 milliseconds per burst? (I just pulled those numbers out of a hat) I need to be able to calculate the volume output of a 500 millisecond burst from say, 130, 150, and 200 cc/min fuel injectors. The results don=92t have to be in metric (though I prefer them), as I=92ve also come across measurements like 45 lbs/hour. Any help would much be appreciated Jason Walters jasonw@xxx.com ------------------------------ From: Scott Hung Date: Tue, 8 Oct 1996 09:39:56 -0700 Subject: RE: 460 EEC-IV info [James wrote:] >I want to put the guts of a 302 distributor (sequential) into the >distributor housing of a 460 (batch). Thus making the 460 dist. capable >of supporting a sequential set-up. Perhaps a call to "SVO" would be appropriate? From Dave William's vendor list: (313)-337-1356. Scott - ---------- ------------------------------ From: Mark Pitts Date: Tue, 8 Oct 1996 19:24:44 +-100 Subject: FW: MAP sensor, etc Damn good point... hadn't thought of that. Mark - ---------- From: Todd King[SMTP:Todd_King@xxx.com] <<< So all these autos in the films is fairly accurate then... what do you guys out there in DIY EFI land prefer? (Manual or automatic transmission) >>> Well for turbo apps the automatic is a better choice (IMO) for full throttle acceleration, at least for keeping the turbo singing happily along during the shifts... Todd Todd_King@xxx.com ------------------------------ From: "Chuck Tomlinson" Date: Tue, 8 Oct 1996 13:18:58 -0400 Subject: Re: Using PC HW (& Ignition timing reference points) > From: tom cloud > > Am I mistaken, or do many of the posts here seem to want to make the cpu > do everything? Take an A/D and read a noisy signal and let the software > filter it (when a simple integrating lo-pass filter would save so much > trouble -- and add, maybe, 32 cents to the cost). Or, try to do all > the ignition timing via internal counters/timers and interrupts, when > maybe a little PLL in the front end could process some of that and make > the cpu / software task lots simpler. I agree in principle, but extra processor work is not a problem if your processor has power to spare. Also, software filters (and other signal processors) are adjustable on the fly. That saves a ton of time and effort, since you only need to write a filter routine once (if you don't just copy it from somewhere else). In our PC-based development controllers, we use software processing for any signal that *might* need to be tweaked. As a result, we build exactly one set of hardware, and do the fine-tuning in software. Our PC processors are so fast that we can simultaneously run the algorithm, process signals, log megabytes'o'data, and run a graphical user interface. All this in addition to being able to post-process the logged data and run the development environment. For the anti-PC folks: if you already know exactly what your algorithm and parameters are going to be, a PC may be the wrong platform. But for maximum development flexibility and fastest progress, *nothing* can beat a PC for anywhere near the money. I have experience with PCs and 68332s. When I build my "release" PCM, it will almost certainly be based on a 6833x or the like. But I will just as certainly do the bulk of my development with a PC. To each their own :-) - -- Chuck Tomlinson ------------------------------ From: Chris Morriss Date: Tue, 8 Oct 1996 18:59:08 +0100 Subject: Re: Ignition timing reference points In message <2.2.16.19961008113303.0c5f7c70@xxx.edu>, Stephen Dubovsky writes > >>I was thinking of adding a 256 or 360 slot optical interrupter disk into >>my distributor to give double the that number of edges every rev >... > > The only problem I see w/ this is dirt. The guys in the motor industry >very rarely use optical encoders because you get a few specs of dust on the >encoder wheel and things go crazy. They almost always prefer some sort of >magnetic/hall sensor type pickup or use a resolver (and then a resolver to >digital converter) if higher accuracy is required. If your interested and >dont know what a resolver is, I can type up some sort of "short" >explanation;) Both of these methods are relatively insensitive to dirt and >grime (unless its a ferrous material...) > > Hope this helps... >SMD > I have often wondered about using a resolver on the distributor drive to measure the position. Although the new price is frightening, there is a lot of old equipment around with them in at give-away prices. At least near me in Nottingham with its big military surplus dealer. (Anchor Surplus). My worry is whether they would tolerate going round at half crank speed for hours and hours. I know they have top quality bearings but is the life adequate? Its not too much problem digitising the sine and cosine output signals. - -- Chris Morriss ------------------------------ From: Dirk Wright Date: Tue, 8 Oct 1996 14:51:02 -0400 (EDT) Subject: D Jet patents OK, the 2 best patents that seem to be the final design choice for the Bosch D Jet system are: #3,430,616 & #3,570,460. There are several other patents that a somewhat related to the D Jet system, but Bosch chose not to use them. Usually, small bits of any system are in a single patent, so it's hard to get the "big picture." For example, there are several patents on variations of the manifold pressure sensor. These 2 patents give the best piscture I've yet found for the whole system. Enjoy. **************************************************************************** Dirk Wright wright@xxx.gov "I speak for myself and not my employer." 1974 Porsche 914 2.0 "A real hifi glows in the dark and has horns." 1965 Goodman House **************************************************************************** ------------------------------ From: marchildon@xxx.net (Alain Marchildon) Date: Tue, 8 Oct 1996 18:57:10 GMT Subject: Boost retard Hi all I would like to build a simple ign retard box similar to the ones by Jacobs and many others, i have a 84 RX-7 GSL-SE this is the first year they put a 13B with fuel injection., i will be adding a Vortech supercharger soon and i was thinking a using a MSD with boost retard but hey this list is up to this task. The rotary engine has a similar firing as a 4Cyl engine so don't be afraid of it ! I would prefer to use a 68HC11, i have a proto board for this. I plan on locking the mechanical and vacuum advance and us a lookup table. The ign pulse would come from the magnetic pickup process it, then send it to the amplifier and to the coil. Ultimately there would be a knock sensor just for safety if ever i go over board with the timing or get a bad batch of gasoline, but the main input for controlling the amount of retard would be vacuum/boost and RPM. If this is to complex maybe just have everything left alone and retard the timing proportional to boost. I could build the board program EPROM's but where i lack the most is in the software skills kneaded for this type of project any one interested give me a buzz. // Marchildon@xxx.net // // Alain Marchildon // // 1984 Mazda RX-7 GSL-SE Soon with Vortech supercharger "My toy // // 1989 Audi 90 "Family car" // ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Tue, 8 Oct 1996 14:03:42 -0500 Subject: Re: Volume of fuel injected ..... >Here's my problem. I'm trying to calculate the volume per burst for a >typical fuel injector. I've downloaded some specifications, but I'm at >a loss to break them down. why wouldn't you fire it 100 or 1000 times into a graduated cylinder and divide the volume by that number?? Tom Cloud ------------------------------ From: Chris Morriss Date: Tue, 8 Oct 1996 19:03:22 +0100 Subject: Re: Volume of fuel injected 1In message <325A7F73.5C5B@xxx.com>, Jason Walters=20 writes >I=92m most definitely not up to the level of expertise of this group, but >I don=92t know where else to field my question. > >Here=92s my problem. I=92m trying to calculate the volume per burst for a >typical fuel injector. I=92ve downloaded some specifications, but I=92m at >a loss to break them down. > >If a given fuel injector has a flow off 150 cc/min, how many >bursts/firings are we talking per 60 second interval? Is that a >measurement with the injector wide open for 60 seconds, or is that a >measurement for something like 50 bursts with a duration of 15 >milliseconds per burst? (I just pulled those numbers out of a hat) > >I need to be able to calculate the volume output of a 500 millisecond >burst from say, 130, 150, and 200 cc/min fuel injectors. The results >don=92t have to be in metric (though I prefer them), as I=92ve also come >across measurements like 45 lbs/hour. > >Any help would much be appreciated > >Jason Walters >jasonw@xxx.com Its normal to have one firing per crank revolution, so the volume per=20 minute is easy to calculate knowing the rpm and the manufacturers data=20 on flow rate. The maximum flow rate given in the specs is under continuous flow=20 conditions I think. (may be wrong though) - --=20 Chris Morriss ------------------------------ From: Kalle Pihlajasaari Date: Tue, 8 Oct 1996 21:35:46 +0200 (sat) Subject: Re: Ignition timing reference points Hi Mark, Stephen, Martin & All, Long message on adding mapped ignition to older vehicles. (Mark, putting our thread back onto the list, seems like there is general interest :-) ========== From: Mark Pitts > More or less exactly what I'm trying to do... My dizzy arm 'pops' on and = > off, why not get a 2nd arm to modify... if you are going to have to take = > the cap off to remove the 'point saver' clip... change the rotor arm as = > well. Yes, easy fix but if I want to keep running compatibility then I can't use the dizzy for the timing input so the centrifugal advance will be close enough to the ignition map for the distributor rotor and I won't need to stretch the rotor lobe as you suggested. > My system is going to be timed off the cranks front pully with some = > small drilled holes in it, and MAP from a T piece in the vac line, all = > I'll have to do is switch between points and electronics on the line = > into the coil. (I might just let the points get beaten to hell anyway! I am reluctant to fit a sensor that is not enclosed as someone/thing will bash it. If I have the point saver clip off one could indeed switch between the two timing systems if the original is left totally as is. On the 4 barrel Alfa I am not real comfotable with manifold pressure sensing as there is no common gallery, I was thinking of using just throttle position for the other map input (on top of RPM). > Next stage after this I to go to wasted sparks, using a pair of Citroen = > 2cv coils, never had one fail in years of motoring in those cars. Yes, I would just stick in 4 standard bosh coils and in this event I would rip out the whole dizzy and replace it with one that has no cap or rotor or centrifugal advance, just the optical encoder. With 4 (or 2) coils one can get 90 deg dwell by turning the next coil on as you fire the current coil. - ---------- From: Kalle Pihlajasaari[SMTP:kalle@xxx.za] > > Just file up a bit of brass plate to extend the edges of the rotor arm, > > and screw or solder it in place! Dont make it any more than the gap > > between the electrodes! Stupid comment but I eneded up with sparks to > > the WRONG cylinder! > > Sounds good. > > I am a little bit of a paranoid delusional maniac at times and am = > thinking > that I would like to leave the original igition untouched in the car > and have a totally separate circuit for my new electronic ignition. > > I figure I could set the timing on the points and dizzy correctly > and then pull the points open with a clip of sorts to avoid wear. > > If I don't put the encoder in the dizzy I would still have standard > centrifugal advance on the rotor and would not need to modify it. > > Then add somewhere on the crank or better yet the camshaft a sealed > optical encoder with a non-glass wheel that is tightly attached > with a 'something' to the cam shaft (DOHC) to give me a new reference. > > A friend suggested the electronic ignition from a V8 Mercedes as = > something > that would always give high energy sparks and then I could use all the > other stuff as standard and if my map fails I can just plug back into > the points to get the car home :-) ========== From: Stephen Dubovsky > >I was thinking of adding a 256 or 360 slot optical interrupter disk into > >my distributor to give double the that number of edges every rev > > The only problem I see w/ this is dirt. The guys in the motor industry > very rarely use optical encoders because you get a few specs of dust on the > encoder wheel and things go crazy. They almost always prefer some sort of > magnetic/hall sensor type pickup or use a resolver (and then a resolver to > digital converter) if higher accuracy is required. If your interested and > dont know what a resolver is, I can type up some sort of "short" > explanation;) Both of these methods are relatively insensitive to dirt and > grime (unless its a ferrous material...) Resolver I know but not realy the guy for the job as it will give you good indication in a alalog fashion and I am a digital person. Another alternative that I discussed with Mark was to couple a sealed insdustrial optical encoder to the overhead cam shaft. (I do not want to take the engine out, real lazy, and beyond me) ========== From: Martin Hill > > From: Kalle Pihlajasaari > > > > I was thinking of adding a 256 or 360 slot optical interrupter disk into > > my distributor to give double the that number of edges every rev > > of the dizzy (or the same resolution on the crank). Is one degree > > on the crank accurate enough for a totally digital one or two of > > design for a mapped ignition. Interrupter disks like this are > > available alone and have usually got an index mark at another > > radius. I could then just replace the cam section with a nice > > shaft without the centrifugal advance (will the rotor still point > > close enough to the correct cap electrode if the rotor is not > > advanced at all and the timing is ? > > > > Just a few thoughts. > > This is far more than enough for a digital system. Most systems > these days use a 36 tooth wheel with one tooth missing to signify > TDC. With the computer it is possible to get accurate enough timing > form this. 360 teeth would provide so much information you would > need a faster processor to keep up. As discussed on one of the other threads, I would make use of extra circuitry to grab the high speed timing, could be as simple as a flip-flop to gate on the timer input from the index mark and then do 4 compares of the timer value in the Micro and then gate of the signal and reset the timer and wait for the next index to start the input pulses again. There are only a few things I am not sure of one is that would a discreet resolution of 1 or 2 degrees crank angle be enough for timing and it seems probable. The second is that is there going to be too much jitter and backlash on the cam shaft, the distributor shaft or the crank shaft to accurately count one degree pulses, in other words would any hypothetical occilation exist that is greater than one degree that would cause multiple counts on the sensor ? Would I have to use of direction information on a quadrature encoder to subtract angle if there is a back fire on start or do I just assume every count edge is one more degree in the correct direction ? I want to do this the brute force way and will probably only ever make two units so am perpared to invest a bit in good encoders unless they actually make the system unworkable. I would however like to keep the system fully digital with timing changing stepwise at the encoder resolution. I would make provision in the circuitry to support the variable inlet valve timing system that could be canibalised from one of the 159i engines. Does anyone know off hand what else would be affected on a carburetted motor if the cam timing were to be changed. It is a step change of around 5 .. 15 degree if I recall. Yeah and what does one do if there are 4 butterflys and no common gallery for manifold vacuum if I were to consider a fuel injection system. The 159i had a flap flow sensor and one butterfly so avoided this problem. Cheers - -- Kalle Pihlajasaari kalle@xxx.za Interface Products Box 15775, Doornfontein, 2028, South Africa +27 (11) 402-7750 Fax: +27 (11) 402-7751 ------------------------------ From: Thor Johnson Date: Tue, 8 Oct 1996 16:41:34 -0400 (EDT) Subject: RE: Using PC HW (& Ignition timing reference points) On Tue, 8 Oct 1996, tom cloud wrote: ..[Mucho good stuff deleted]... > > Now, understand, I really haven't thought about perzactly how to do all > these things. Just wondering if anyone else has. It is my experience > that being too much the purist (i.e. a hacker / fanatic trying to make > the confuser doo it all) puts you way up on the diminishing returns curve, > when the most expeditious (isn't that a new Ford product?) approach would > seem to be to use any and all tricks to get what we want. [Now, if what > you want is to play wid da cornfuser, so be it. As I've said before, I > wanna D-R-I-V-E !] Well put! I have seen both extrems of design in IEEE hardware contests (one design was *completely* analog - to reprogram, change resistors), & I think that there is a lot to be sair for a hybrid design. It is amazing what one can do with a R & a C & a CMOS gate! Thor Johnson johnsont@xxx.edu http://falcon.mercer.peachnet.edu/~johnsont Have you seen the WarpMap lately? http://falcon.mercer.peachnet.edu/~johnsont/warpmap ------------------------------ From: Jason Walters Date: Tue, 08 Oct 1996 14:51:37 -0700 Subject: Re: Volume of fuel injected tom cloud wrote: > > ..... > > >Here's my problem. I'm trying to calculate the volume per burst for a > >typical fuel injector. I've downloaded some specifications, but I'm at > >a loss to break them down. > > why wouldn't you fire it 100 or 1000 times into a graduated cylinder > and divide the volume by that number?? > > Tom Cloud That's a very good idea, but I don't have an injector or a test bench (yet) to try it out on. I'm on a super fixed budged for this research project, and I'd hate to end up with an injector I couldn't use. (I'm doing some calculations to see if a device I came up with is viable.) Now that I know the CC/Min spec is for a wide open injector, I'll buy the appropriate injector, and calibrate my device's firing time/output with a graduated cylinder. Thanks for the quick turn around on my question!! Jason Walters jasonw@xxx.com ------------------------------ From: "S. McManus" Date: Tue, 8 Oct 1996 15:16:23 -0700 (PDT) Subject: Re: Volume of fuel injected Jason: The volume (or mass) flow rate usually given is for an injector being held open (static flow). For example, if you took an injector rated at 200cc/min= , supplied it with the recommended fuel pressure, and opened it for one minute, you should have very close to 200cc of fuel on your floor. =20 What's probably more important though is dynamic flow. You should be able to get a spec for the volume/mass for say a 2.5 ms pulse width. This will be quite different than what you would calculate from the static flow, due mainly to the fact that the fuel has mass and therefore takes a finite amount of time to accelerate to the static flow rate. (theoretical calculation: [volume delivered(grams)]=3D[pw(seconds)]*[static mass flow rate(grams/sec)]) On the other hand, if you truly had a 500 ms (1/2sec) second pw, dynamic and static flows would be practically equal. Sean McManus University of Washington Mechanical Engineering =20 On Tue, 8 Oct 1996, Jason Walters wrote: > I=92m most definitely not up to the level of expertise of this group, but > I don=92t know where else to field my question. >=20 > Here=92s my problem. I=92m trying to calculate the volume per burst for = a > typical fuel injector. I=92ve downloaded some specifications, but I=92m = at > a loss to break them down. >=20 > If a given fuel injector has a flow off 150 cc/min, how many > bursts/firings are we talking per 60 second interval? Is that a > measurement with the injector wide open for 60 seconds, or is that a > measurement for something like 50 bursts with a duration of 15 > milliseconds per burst? (I just pulled those numbers out of a hat) >=20 > I need to be able to calculate the volume output of a 500 millisecond > burst from say, 130, 150, and 200 cc/min fuel injectors. The results > don=92t have to be in metric (though I prefer them), as I=92ve also come > across measurements like 45 lbs/hour. >=20 > Any help would much be appreciated >=20 > Jason Walters > jasonw@xxx.com >=20 ------------------------------ End of DIY_EFI Digest V1 #305 ***************************** 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".