DIY_EFI Digest Wednesday, 14 February 1996 Volume 01 : Number 042 In this issue: Re: Fuel Injector Valve Phasing... Extra Fueler Re: MAP Questions... Re: MAP Questions... Re: MAP Questions... EFI 332 Home page?? Re: Multiprocessor system - Who uses intel ups Re: MAP Questions... Re: Multiprocessor system Re: MAP Questions... See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: dave.williams@xxx.us (Dave Williams) Date: Mon, 12 Feb 1996 21:11:00 +0000 Subject: Re: Fuel Injector Valve Phasing... - -> I have some photo's, taken by John De Armond, of two Rx7 injectors, - -> 280 Z injector, and a GM injector. All are port injectors (not - -> throttle body), and they have drastically different patterns. Actually, it was John who was showing me the patterns. The "pattern" in the photos is only present for a small percentage of the injector's cycle time. The rest of the time it's dribbling on or dribbling off. ------------------------------ From: Cliff@xxx.au (Cliff Tindall) Date: Tue, 13 Feb 96 21:00:53 +0800 Subject: Extra Fueler Hi. I have a small timer circuit that I have built that I have used to control an extra injector, under full load situations, in a modified engine (for off road racing)using the existing injector pulse to trigger the unit, and switches for full load etc. This works well in its current application. However I have someone who would like a unit to fit to their Turbo LPG (propane)to come on only at boost. This is no problem to do with a pressure switch, but the problem now is what to trigger the unit from. What I want to do is use the coil - signal. To pulse at the same rate as before I now need a divide by 3 circuit. So the unit will pulse once per engine revolution. My first thoughts were to use CMOS flip flops, but as I have seen from some of the posts on DIY_EFI I may be doing work that has previously been done. Any suggestions are welcome. Cliff Tindall Perth, Western Australia - -- - -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- Onramp BBS - Perth, Australia http://www.onramp.com.au/ - -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=- ------------------------------ From: atsakiri@xxx.com Date: Tue, 13 Feb 96 08:38:39 -0500 Subject: Re: MAP Questions... > This is what I know. The MAP sensor will give me a reading on the manifold > vacume. I can correct this with a temp sensor to give the amount of air that > the > engine desires. I was wondering how I would go about using this sensor to > determine how much air I need. That's got me a bit confused. Could you restate that part? > Is a MAP system just mapped out? Like an array. Where temp is one > demension, Vac is the second dimesnion and the array value is the fuel. Take > this data for several points on the RPM curve then when the engine is running > have it integrate the curve data and find the appropriate value for fuel? Isn't the goal of most MAP-based systems the same as that of MAF-based systems, namely to estimate the mass of air inducted into the cylinder? For a MAP-based system, this would be an application of the ideal gas law with the addition of a volumetric efficiency term. pV = mRTe where p = manifold absolute pressure V = cylinder displacement m = air mass inducted R = gas constant T = absolute temperature e = volumetric efficiency . . . This could also be expressed in rate terms ... pV = mRTe where V is determined by engine speed. This is a very simple approach. I think the difficulties arise in determining volumetric efficiency, which varies with temperature, barometric pressure (mainly an exhaust-side effect), etc. The maps you speak of would be of volumetric efficiency and various correction factors. As to size of the sensors, I've seen them at about 80 mm x 50 mm x 15 mm. Anthony Tsakiris - --------------------------------------------------------------------------- The opinions expressed are my own and not necessarily those of my employer. ------------------------------ From: robert dingli Date: Wed, 14 Feb 1996 10:54:25 +1100 (EST) Subject: Re: MAP Questions... > > Jim, have you considered a simple speed throttle system using throttle > > position > > and rpm to index a map? > > Robert, > The problem I have requires that it operate over very wide range of > temperatures and altitudes. A TPS system would be very simple and I could do it > with the scrap parts on my desk but it wouldn't be the best I could make it. > Also I would have to have a butload of calibration curves for it based on the > temp and altitude. I can check the temp no problem, I've got a small integrated > 0¡C to 100¡C National Semiconductor temp sensor. But I need some type of > correction for the pressure. Jim, you can simply map the injection duration per cycle as a function of rpm and throttle position and then correct for ambient air temperature and pressure. The air pressure would be measured in free air or, if you used some sort of ram air intake, inside the air box before the throttle. > This is what I know. The MAP sensor will give me a reading on the manifold > vacume. I can correct this with a temp sensor to give the amount of air that the > engine desires. I was wondering how I would go about using this sensor to > determine how much air I need. > Is a MAP system just mapped out? Like an array. Where temp is one > demension, Vac is the second dimesnion and the array value is the fuel. Take > this data for several points on the RPM curve then when the engine is running > have it integrate the curve data and find the appropriate value for fuel? With > an O2 sensor taking up the rear with corrections with are stored in some sort of > temp table? Just a thought----- After all I'm using a PC (286 w/ 287) So I > have all the horse power I need. As above, you can simply map the injection duration as a function of rpm and MAP value, and then correct for air temperature using the ideal gas law or whatever is most appropriate for your intake system. Thus, rpm is one dimension, MAP the other, and the array value the fuel injected per revolution (or cycle). Initially, you could meter the fuel as a linear function of MAP only. From my experiences with single cylinder engines, there generally isn't a suitable MAP value to work from. You could try mechanically filtering the MAP value with a restriction in the pressure line. I doubt your B&G will run well anywhere near stoiciometric, so unless you have a wide range UEGO (Universal Exhaust Gas Oxygen) sensor, you will have to run open loop. A 286 may be good as communicating with a screen or other computer peripherals but communicating with the real world is another matter. While the processor will have sufficient grunt, you will probably be restricted by the input and output systems. regards, Robert - -- Robert Dingli r.dingli@xxx.au Power and Control Systems (+613) 9344 7966 Thermodynamics Research Labs (+613) 9344 7712 University of Melbourne, AUSTRALIA ** he who dies with the most toys, wins ** ------------------------------ From: MTaylorfi@xxx.com Date: Tue, 13 Feb 1996 20:08:28 -0500 Subject: Re: MAP Questions... PV=nRT is for a static situation, which is rather boring for an engine! Try Bernoilli (sp?) equation. See ya, Mike ------------------------------ From: Jody Shapiro Date: Tue, 13 Feb 1996 20:32:35 -0500 Subject: EFI 332 Home page?? Is the EFI 332 home page still up at its (as far as I know) current location of: http://www.cim.swin.edu.au/wwwhome/aden/efi332/332_index.html Can't seem to get there, although the server seems to be up (www.cim.swin.edu) Thanks, - -Jody - --- http://www.cs.cornell.edu/Info/People/jshapiro/jshapiro.htm ------------------------------ From: "Zublin, Bryan (SD-MS)" Date: Tue, 13 Feb 1996 16:31:00 -0800 (PST) Subject: Re: Multiprocessor system - Who uses intel ups Martin Mayhead (mpm@xxx.com) writes: >If your question was aimed at discovering the pitfalls and/or >advantages of Intel uC's (in particular the 80196) I would be >happy to discuss this further - it is actually very straightforward >to use and well documented by Intel (yes that surprised me too). I'd like to hear more about the advantages/disadvantages of the 80196 when used for an efi/spark timing controller. We use quite a few of them in our satellite receivers, so they are readily available for me. The Motorola uC's seem to get the most attention on this list, it would be good to hear about the "competition." Bryan Zublin bzublin@xxx.com ------------------------------ From: pantera@xxx.com (David Doddek) Date: Tue, 13 Feb 1996 22:31:33 -0600 (CST) Subject: Re: MAP Questions... > Well, now that I know a ton about MAF. I came to a great revolation. I >checked the minimum air flow specs and I'm not even close to the turn on flow at >full power!!!!! > So much for the power of a briggs and stratton. But a MAP sensor is the next >bet, or any Barametric Pressure Sensor. Does anyone know of any good ones? > What are the dimesions of you average MAP? hieght, width, etc> > What is the output type, and range? >Analog Prefered of course. > Lastly how exactly can it tell me how much air is flowing in the engine? > > Thanks.... > Jim Staff > > Jim, A map sensor from a gm car will work just fine. It has a 0v (0kpa absolute) to 5V (100 kpa absolute) analog signal. One thing to remember about the briggs, is that the small displacemant 1 cylinder will not develop a stable vacuume signal. You may need to make an intake with some type of volume, say equal to the engine displacemant to act as a buffer. Or else use a very fast a-d converter and average or filter the signal in software. As has already been mentioned, the amount of air in the engine can be defined by the ideal gas law. Think about it this way, If there is little air pressure, then there is little air. A lot of air pressure means that there is a lot of air. Since the ratio of fuel to air is to be pretty much constant, the amount of fuel is related to the air pressure in the intake. This is pretty general, but is a start. The dimensions of the gm map sensor are roughly 1" by 1.5 " by 4" and uses a 3 pin packard connector operating on 5 volts. David J. Doddek |pantera@xxx.com Owner SGD Electronics & Development Engr for Caterpillar |h 309 685-7965 Formula SAE Team Sidewinder 94-95 |w 309 578-2931 89 T-bird SC, 69 Fairlane w/SGD EFI |fx 217 428-4686 74 Pantera w/Electromitive Tec-II Twin turbos and Nitros | Hey, If you are going to go fast, go REEEAAL FAST. | ------------------------------ From: Steve Baldwin Date: Wed, 14 Feb 1996 19:37:13 +1300 (NZDT) Subject: Re: Multiprocessor system > ************************************************** > Well by golly Peter...Don't YOU have a spell checker down there???? > >************************************************* You'll have to excuse him. I ran over his foot while trying to park the dragster. :-) Steve. ------------------------------ From: arthurok@xxx.com (ARTHUR OKUN ) Date: Tue, 13 Feb 1996 23:45:38 -0800 Subject: Re: MAP Questions... how about a servo controlled throttle plate if done propperly it might alliviate alot of efi problems caused by manualy controled throttles : just think no more lead foots causing the manafold pressure to go down to next to nothing. ------------------------------ End of DIY_EFI Digest V1 #42 **************************** 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".