DIY_EFI Digest Wednesday, 31 January 1996 Volume 01 : Number 027 In this issue: 1cylinder-ignition_68HC11 Re: Sensor Questions? DIY_EFI www pages RE: Commercial systems re: Re: Sensor Questions? What processor does GM use Re[2]: Commercial systems (regulator) Re: Finding out Fuel Consumption. re: Re: Sensor Questions? Still more questions... Re: Re[2]: Commercial systems (regulator) re: Re: Sensor Questions? Re: Sensor Questions? SBC TPI manifold questions Re: Nissan EFI connection Re: Sensor Questions? Re: Re: Sensor Questions? RE: Commercial systems MAF vs. MAP Re: Re: Sensor Questions? See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Hans Hintermaier" Date: Tue, 30 Jan 1996 11:02:10 MET Subject: 1cylinder-ignition_68HC11 My name is Hans Hintermaier, i am a 32years old toolmaker and live near Munich, germany. My hobbies are old motorcycles and combustion engines generally. Please pardon my english! I started to work on microcontrollers several months ago while i was trying to repair a flywheel-regulator of a 1956 NSU 1 cylinder 125ccm ignition. I AM a mechanic-freak, but that kind of regulator was never working as good as I wanted it to work, even when it was new. So i began with building an e-motor driven regulator-simulator.(maybe i'll send a photo of it later) The controller-breadboard was not the problem, nor to get development-software. The real problem was, that i had no experience in programming, generally. Though my (only simulator-tested) programs are very simple, but work quite well. The next step should be an EFI. So i searched for "fuel injection" in Internet, and was very surprised to find You! The source code of my programs is not jet documented, so i will send them later. If someone is interested in my work, contact me at HIHA@xxx.de hiha@xxx.de ------------------------------ From: Wayne Braun Date: Tue, 30 Jan 1996 09:55:00 -0600 Subject: Re: Sensor Questions? Stuff Deleted... > In the GM ECM's, whether you are in CL or not, the ECM is running > through the same 'preprogrammed' code. Closed loop adds the ability > for the BLM to learn. If not in closed loop, the BLM is still used, > and if not altered by a complete power off, will still correct the fuel > mixture from what it has learned. > > Part of the equation is: > > Fuel = Integrator * BLM * (rest of fuel calculation) > > In open loop, the integrator is set to neutral. The BLMs are whatever > has been learned, so the fuel correction still goes on. One caveat is > that some ECMs will check (and reset) the BLMs at ignition power on for > a tighter limit than is allowed during normal operation. The same > things happen when in PE, i.e., the integrator goes neutral, and the > BLM is whatever has been learned. > > The only thing that closed loop adds is the ability to learn, and > the integrator (with help) keeps the fuel about 14.7 AFR. > > Scot Sealander FIScot@xxx.com > O.K. call me what ever names you would like here ***BUT*** what are the acronyms BLM and PE supposed to stand for????? Yes I know in this context, CL is Closed Loop and conversly OL would be Open Loop. Many people seem to neglect to explain the shortened terms that they use. In a lot of cases, no one questions this. After all, if you do not even know what "THAT" means well you obviously don't know much at all. Well fine, I'll admit it, I don't. So educate me a little and explain what you mean. Unfortunately, this points directly at Mr. Sealander and I do not mean to single him out as the only person that does this. After all, he is NOT the only person that does this. I ended up re-reading one paragraph several times ( in someone elses posting ) before the term "catcon" fell into place as meaning catalytic converter. In North American automotive circles, when someone writes SBC, you can be reasonably assured that what they mean is the Small Block Chevrolet engine. However, this may not necessarily be the case in Germany, Sweden, or Australia. I an sure that each of these countries has developed their own set of abbreviations that have little or no meaning here ( unless explained ). If we could just be a bit more carefull about how we explain things some of the postings would be a lot clearer. Mr. Sealander, I do enjoy reading the information that you have provided even if I sometimes have to work to understand them ( that may not be a bad thing either 8^)). Regards Wayne Braun Wayne Braun Product Support Develcon Electronics Email: Wayne.Braun@xxx.com Phone: (306) 933-3300 or 1-800-667-9333 FAX: (306)978-8860 ------------------------------ From: fridman@xxx.ca (Robert Fridman) Date: Tue, 30 Jan 1996 10:08:56 -0700 Subject: DIY_EFI www pages For all new commers to the DIY_EFI list, the DIY_EFI web pages reside at http://www.cpsc.ucalgary.ca/~fridman/diy_efi If you want to add to this collection (private home pages or projects) please let me know. RF. - ------------------------------------------------------------------------- 83 R100 DoD 749 Robert Fridman 84 320i fridman@xxx.ca ------------------------------ From: Jim Pearl Date: Tue, 30 Jan 1996 13:32:30 -0600 Subject: RE: Commercial systems - ------ =_NextPart_000_01BAEF17.68538420 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I too have spoken to some of these guys. I currently own one of the = older DFI systems and I'm pretty sure it's either batch fire or bank = fire as you described. They DO however have a fully sequential system = I'm told but I'm sure it's more expensive. From the reading I've done = the fully sequential systems supposedly don't add much hp but I believe = that they will add mpg and possibly drivability. Make sure the system = you decide upon can handle peak hold injectors, I'm pretty sure most of = the after-market ones do but... I guess my biggest gripe with the DFI is = that it won't adjust for voltage drops well and that the software leaves = a bit to be desired. Some of the Electromotive software will actually = help you program the computer for you and can use a MAF sensor - not so = the DFI. You're MAP only and on your own to program the maps, even the = instructions aren't real clear with regards to the idle maps and decel = maps. Some of the "controls" aren't intuitive to me (sigh). I'm told = they are no longer doing development on this system or it's software, = Electromotive on the other hand doesn't ever seem to stand still. Electromotive. These guys seem to have a really good system although = I've been told their harnesses aren't terrific. Their software is also = outrageous unless the prices have dropped recently. IMHO Electromotive = IS a pretty good source for airdoors and throttlebodies etc.. Street and = performance might also be a good source for parts but Electromotive = sells fuel rail in bulk as well as the little bungs to be welded\epoxied = into a manifold. With the exception of the software pricing and some = stories of varying price quotes I've heard about them they're pretty = good (IMHO - they're also local to me.. My biggest reason for not going = with them was that it would be pretty obvious I didn't have the stock = computer with their system and PRICE. The DFI likely cost me HALF what = an Electromotive system would. Short of pirating the software there's no = way I could've afforded them, pretty sad.. As for fuel pressure, most fuel regulators are vacuum\boost referenced. = When vacuum hits it drops the pressure making for a better idle and then = jumps up when you hit 0 inches, depending upon the regulator boost is = 1:1 unless you use some sort of FMU. I myself prefer to stay away from = Fuel Management Units like Vortech and others use as the one's I've = tried were far from linear and deadheaded my pump - not good! Anyway, that's my $.02. Feel free to ask any questions you might have = and I'll try to help just keep in mind that a friend recently looked at = my maps and asked me if I had ANY idea what I was doing (grin)... - ---------- >From: Bill[SMTP:mymove@xxx.net] Sent: Monday, January 29, 1996 11:22 PM To: diy_efi@xxx.edu Subject: Commercial systems Although I am keenly interested in diy_efi, the schedule of my current project requires that I purchase a commercial system. I seems that the = big players are Haltech, DFI, and Electromotive. Does anybody have any experience with any of these organizations? I've spoken with them over = the phone and although all seem to be knowledgable, have imparted more than = a little confusion. I'm told by a competitor of Haltech, for example, = that Haltech is a "bank-fired" system.....meaning that after the calculations = are complete, all 4 injectors on 1 side of a V-8 are fired simultaneously, = then the sequence repeats for the other side, and so on. Has anyone ever = heard of such a system? =20 I'm also wondering about how the effect of manifold vacuum or pressure affects the rate of fuel delivery, all other factors being equal. For example, if a given pulse width results in 10 #/hr of fuel with a given = fuel rail pressure, does that mean "on the bench"? What happens when the = same injector is spraying into a 10" or 20" Hg vacuum? Does that tend to = suck extra fuel. Or what happens when the boost is run up to 20 psig? = Clearly, its the pressure differential that is at issue here. And nobody seems = to be talking about modulating fuel rail pressure in response to manifold conditions in an attempt to keep the pressure differential constant. Is this really an issue, or am I making this more complex than it has to = be? Lastly, does anyone know of a commercial system that is soon to be = retired in favor of a later model? Or does anyone have a funtional DIY_EFI for = sale at this time? My parameters are as follows: Small block Chevrolet motor (377 cu in) in flat-bottom V-drive = boat (2) AiResearch TO-4 turbos Powerglide Crank-driven ignition Gasoline fuel with methanol enrichment at higher power levels (>5 psig boost) 6000 RPM maximum Thanks for any and all information. = =20 William Sarkozy = =20 Kalamazoo, MI - ------ =_NextPart_000_01BAEF17.68538420 Content-Type: application/ms-tnef Content-Transfer-Encoding: base64 eJ8+IiATAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAENgAQAAgAAAAIAAgABBJAG AGQBAAABAAAADAAAAAMAADADAAAACwAPDgAAAAACAf8PAQAAAGMAAAAAAAAAgSsfpL6jEBmdbgDd AQ9UAgAAAABkaXlfZWZpQGNvdWxvbWIuZW5nLm9oaW8tc3RhdGUuZWR1AFNNVFAAZGl5X2VmaUBj b3Vsb21iLmVuZy5vaGlvLXN0YXRlLmVkdQAAHgACMAEAAAAFAAAAU01UUAAAAAAeAAMwAQAAACMA AABkaXlfZWZpQGNvdWxvbWIuZW5nLm9oaW8tc3RhdGUuZWR1AAADABUMAQAAAAMA/g8GAAAAHgAB MAEAAAAlAAAAJ2RpeV9lZmlAY291bG9tYi5lbmcub2hpby1zdGF0ZS5lZHUnAAAAAAIBCzABAAAA KAAAAFNNVFA6RElZX0VGSUBDT1VMT01CLkVORy5PSElPLVNUQVRFLkVEVQADAAA5AAAAAAsAQDoB 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FIScot@xxx.com Wrote: | >| Is this assumption correct, or have I credited the engine computer | >| with too much "intelligence"?? | >| John | | > John, you are correct, my description above was a little simplistic. | > As long as the ECM is in closed loop, it will adapt (within the block | > learn limits). If you aren't closed loop, though, pre-programmed | > values are used which will result in a lean condition. | > Steve Ravet | | In the GM ECM's, whether you are in CL or not, the ECM is running | through the same 'preprogrammed' code. Closed loop adds the ability | for the BLM to learn. If not in closed loop, the BLM is still used, | and if not altered by a complete power off, will still correct the fuel | mixture from what it has learned. | | Part of the equation is: | | Fuel = Integrator * BLM * (rest of fuel calculation) | | In open loop, the integrator is set to neutral. The BLMs are whatever | has been learned, so the fuel correction still goes on. One caveat is | that some ECMs will check (and reset) the BLMs at ignition power on for | a tighter limit than is allowed during normal operation. The same | things happen when in PE, i.e., the integrator goes neutral, and the | BLM is whatever has been learned. | | The only thing that closed loop adds is the ability to learn, and | the integrator (with help) keeps the fuel about 14.7 AFR. | | Scot Sealander FIScot@xxx.com Interesting, Scot. It doesn't seem that there is really a need for a MAF, then. Is MAF just an aid to enable the CPU to learn better? Or is there a MAF term in the fuel equation? - --steve Steve Ravet sravet@xxx.com Baby you're a genius when it comes to cooking up some chili sauce... ------------------------------ From: frank.micciola@xxx.com (Frank Micciola) Date: Tue, 30 Jan 1996 14:53:41 -0500 Subject: What processor does GM use Could anyone tell me what micro processors GM uses for it's ECM boxes Thank You frank.micciola@xxx.com ------------------------------ From: wmcgonegal@xxx.ca Date: Tue, 30 Jan 96 15:06:07 EST Subject: Re[2]: Commercial systems (regulator) >Bosch makes a nice one for only about 60 CND. Have par number if you >need it, but you need to get an adaptor to make it pressure regulated. >Muhammed Hadzic >Queens University >Kingston, Ontario >Canada I would like to get the part number and supplier of the Bosch pressure regulator you mentioned. Will McGonegal Mobile Sources Emissions Division Environment Canada wmcgonegal@xxx.ca ------------------------------ From: "Brian Warburton, c/o Turbo Systems Ltd" Date: Tue, 30 Jan 1996 20:29:08 Subject: Re: Finding out Fuel Consumption. >I am currently doing a microprocessor project using an 8051. >What I am building is a simple Fuel / Trip computer. > >I have a 1993 Ford Thunderbird with a 5.0H.O. engine. Someone told me = >that Pin 34 on the EEC computer relates to how long the fuel injector is = >open. Almost the right answer, but wrong enough to waste you a lot of time assuming that NAAO (North American Automotive Operations) trip-minders work the same as FOE (Ford of Europe) ones. In FOE, pin 34 outputs a series of pulses which relates to fuel consumption. The relationship tho' is the number of pulses not the pulse width. It used to be either 6000 or 8000 pulses to the (euro) gallon, but that's something that can easily be determined by testing (i.e. fill the tank and count up the pulses while waiting for the fuel to run out). ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Brian Warburton, "Still searching for the perfect curve....." email: bwarb@xxx.net Advanced Automotive Electronics Ltd, Van-Nuys House, Scotlands Drive, Farnham Common, England. SL2-3ES ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ------------------------------ From: Markus Strobl Date: Tue, 30 Jan 1996 15:47:52 -0600 Subject: re: Re: Sensor Questions? The Q of MAF vs speed density has come up in 2 mailing lists at once, so this goes out to both lists... > Interesting, Scot. It doesn't seem that there is really a need for a MAF, > then. Is MAF just an aid to enable the CPU to learn better? Or is there a > MAF term in the fuel equation? > > --steve I like to think about it this way (it is a bit simplified, but it's basically true): A speed density (SD) system will only know how much air is entering the engine as a percentage of the maximum flow. For instance, driving at half throttle at a certain condition may tell the ECM the engine is using 50% of maximum flow. Dyno test run by the manufacturer indicate that max flow is 600 cfm (cubic feet per minute) of air. The ECM then knows how much fuel to inject for 300 cfm of air. This sounds like a perfect setup, until you start to think about it. Production tolerances will affect max flow in an engine (casting flash, mismatched cylinderheads-to-manifold, etc). Also, max flow will change as the engine ages. And we haven't even started considering modifications such as ported heads, hotter cam etc. So as soon mods are made to a SD engine, a new chip has to be burnt. The solution to this is the MAF (mass air flow) sensor. Instead of measuring the percentage of maximum flow, it measures the actual amount of air that enters the engine. After some corrections for air temperature (simple) the ECM can then calculate the required amount of fuel. A MAF engine will respond very well to modifications, aging, production tolerances etc. Only drawback is slightly higher cost, and the restriction of the sensor in the intake path. Modern MAF systems also have a MAP (manifold absolute pressure) sensor that makes it a complete SD system. The ECM continuesly compares MAF to SD while in closed loop to try and catch a MAF failure. If it determines that the MAF has failed (ie MAF value is *really* out of whack compared to SD), the ECM will run in SD mode and disable the MAF. > Steve Ravet Markus Strobl 96 Z28 6M Black/grph. Borla, !CAGS, PEG2, QLC Dallas, Texas 1LE driveshaft, Honker, T-tops, CD, leather F-member 9/93 14.09 @xxx.5mpg @85mph ------------------------------ From: "Jim Staff" Date: Tue, 30 Jan 1996 23:56:15 GMT Subject: Still more questions... Thanks to everyone who's been keeping me informed about all this stuff. I've made a great deal of progress. To the point were I have it all the way down to the timing system!!!! I've settled for a DAC for O2 and a DAC for temp. I'm using a standard CTC @ 8mhz. So I have great resolution 2µs. I run it to a D type Flip flop for the switching component. I address the counter, load the timer information. Then I set the D flip flop to a 1 and trigger the counter at the same time. The counter counts down after the trigger signal and then sends a +5V pulse at timeout. This resets the Flip flop ending the pulse cycle. The Ignition system is being run most likely straight from a bipolar transistor. Rated for 25V @xxx. A D typr flip flop is again used as an addressable switch and is then fed into an or gate which resets the correct position. (NOTE : The excess volatage is dropped by a series of 2 diodes that sink 1.0V apeice. So a logic 0@xxx. Only a 1 @xxx.) Question #1 : Can a magnetic field collapse in 125ns? If not what is the recomended minimum time? The injection system for my application must be very small. Since a B&S 3hp lawn mower engine has a very small cylinder. Question #2 : What is the typical flow of an injector? What is the best/typical way to hook up a port injector? Part 3 what is the best kind of fuel pump setup that I could use to power an injector? The last thing I have to do is to set up this stuff on my Briggs. I'll probably weld a Port injector holder next to the intake port with a fuel line hose attachment. I'll place my MAF sensor in a carb hood. The temp sensor I'll put next to the MAF, and the O2 sensor next to the exhaust port as close as possible because I have it set up as a straight pipe. But after I set all this stuff up I need something to use as a model so could you answer problem #3. Question #3 : What is the general equation for air to fuel mixture? I know is has a temp term, a fuel term (Å14.3:1 ideal), a MAF derived term (If I'm not mistaken it pulses for every X liters/sec) Add in question : What are the specs on some MAF sensors, Temp Sensors, O2 sensors, and any general help about their placement.. Thanks for answering my questions. I know I must be an horrible burden on everyone but I have to beat Grand Rapids. They obtained a bosch injector and adapted it to thier car and got Å750 MPG. Our school ran stock class and got 128MPG wich won us 3rd place!!! Jim Staff ------------------------------ From: pantera@xxx.com (David Doddek) Date: Tue, 30 Jan 1996 19:39:35 -0600 (CST) Subject: Re: Re[2]: Commercial systems (regulator) >>Bosch makes a nice one for only about 60 CND. Have par number if you >>need it, but you need to get an adaptor to make it pressure regulated. > >>Muhammed Hadzic >>Queens University >>Kingston, Ontario >>Canada There is another good pressure regulator on the market. It is made by mallory. It has an adjustment range of 3 to 60 psi and is vacuume referenced for EFI. It has a high flow rating and can be used on engines in excess of 1000HP. That is what I am using on my car. The connections are also in 3/8 pipe thread, so it can be attached with hose barbs or attached directly to a fuel rail. The part number is Mallory 250 series 3 port regulator the price is $66.95 US They can be ordered from Summit automotive The summit part number MAA-4309 And phone 216-630-0200 And Summit will ship any where in the world. 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: arthurok@xxx.com (ARTHUR OKUN ) Date: Tue, 30 Jan 1996 18:09:10 -0800 Subject: re: Re: Sensor Questions? You wrote: > >The Q of MAF vs speed density has come up in 2 mailing lists at once, >so this goes out to both lists... > > >> Interesting, Scot. It doesn't seem that there is really a need for a MAF, >> then. Is MAF just an aid to enable the CPU to learn better? Or is there a >> MAF term in the fuel equation? >> >> --steve > >I like to think about it this way (it is a bit simplified, but it's >basically true): > >A speed density (SD) system will only know how much air is entering the >engine as a percentage of the maximum flow. For instance, driving at half >throttle at a certain condition may tell the ECM the engine is using 50% >of maximum flow. Dyno test run by the manufacturer indicate that max >flow is 600 cfm (cubic feet per minute) of air. The ECM then knows how >much fuel to inject for 300 cfm of air. > >This sounds like a perfect setup, until you start to think about it. >Production tolerances will affect max flow in an engine (casting flash, >mismatched cylinderheads-to-manifold, etc). Also, max flow will change >as the engine ages. And we haven't even started considering modifications >such as ported heads, hotter cam etc. > >So as soon mods are made to a SD engine, a new chip has to be burnt. > >The solution to this is the MAF (mass air flow) sensor. Instead of measuring >the percentage of maximum flow, it measures the actual amount of air that >enters the engine. After some corrections for air temperature (simple) >the ECM can then calculate the required amount of fuel. A MAF engine >will respond very well to modifications, aging, production tolerances >etc. Only drawback is slightly higher cost, and the restriction of the >sensor in the intake path. > >Modern MAF systems also have a MAP (manifold absolute pressure) sensor that >makes it a complete SD system. The ECM continuesly compares MAF to SD while >in closed loop to try and catch a MAF failure. If it determines that the >MAF has failed (ie MAF value is *really* out of whack compared to SD), the >ECM will run in SD mode and disable the MAF. > > >> Steve Ravet > >Markus Strobl 96 Z28 6M Black/grph. Borla, !CAGS, PEG2, QLC >Dallas, Texas 1LE driveshaft, Honker, T-tops, CD, its >F-member 9/93 14.09 @xxx.5mpg @85mph > its hard to build a non microprocessor based fi system without a maf ; think about it. ------------------------------ From: FIScot@xxx.com Date: Tue, 30 Jan 1996 21:40:27 -0500 Subject: Re: Sensor Questions? Subj: Re: Sensor Questions? Date: 96-01-30 15:17:01 EST From: Wayne.Braun@xxx.com (Wayne Braun) > O.K. call me what ever names you would like here ***BUT*** what are > the acronyms BLM and PE supposed to stand for????? BLM = Block Learn Memory PE = Power Enrichment > Yes I know in this context, CL is Closed Loop and conversly OL would be > Open Loop. > Many people seem to neglect to explain the shortened terms that they > use. In a lot of cases, no one questions this. After all, if you do > not even know what "THAT" means well you obviously don't know much at > all. Well fine, I'll admit it, I don't. So educate me a little and > explain what you mean. Guilty as charged. BLM is usually a 4x4 matrix that has on one axis an RPM component and on the other, a load component. This matrix is updated when the ECM is in closed loop and BLM learn conditions are met. The particular BLM that is used is defined by the particular combination of RPM and load. If the ECM is operating in open loop, the ECM can still operate close to the ideal AFR (air/fuel ratio) by using the 'learned' value of BLM. Seeing as GM does not necessarily use hard and fast rules, the number of BLM locations can be as few as 2, to as many as 16 BLM locs. (Personal experience cited.) > Unfortunately, this points directly at Mr. Sealander and I do not mean > to single him out as the only person that does this. After all, he is > NOT the only person that does this. I ended up re-reading one > paragraph several times ( in someone elses posting ) before the term > "catcon" fell into place as meaning catalytic converter. I guess we all sometimes assume a basic level of understanding that is uniform all around. [text deleted] > If we could just be a bit more carefull about how we explain things > some of the postings would be a lot clearer. I suppose that I could take a little more time. I forget that everyone on the list may not understand all those acronyms. ;-) I can't give proper credit here, but someone did define a lot of acronyms here on the list. Look in the archives for the info. > Mr. Sealander, I do enjoy reading the information that you have > provided even if I sometimes have to work to understand them ( that may > not be a bad thing either 8^)). Hey, that's good for you! There is really is no substitute for personal effort! Scot Sealander FIScot@xxx.) ------------------------------ From: jsg (John S Gwynne) Date: Tue, 30 Jan 1996 21:52:18 -0500 Subject: SBC TPI manifold questions Just a couple of quick question... I don't really want to buy a service manual for this car since I only have its manifold. Manifold: 89 Camaro TPI 305 w/ cold start injector Q) The EGR valve has what looks like a temperature sensor built into its base. How is that used? Q) I've traced the idle air passages down through the base plate. Near the cold start injector there is a hose nipple. What attaches here? Does this tee-off to the MAP sensor which I assume is attached to the rear left nipple on the plenum? Q) How did GM originally route the radiator bypass hoses? One through the throttle body then back to the block and a second to the heater? Thanks, John Gwynne ------------------------------ From: Wayne Cox Date: Tue, 30 Jan 1996 22:03:33 -0500 Subject: Re: Nissan EFI connection Hi All. I just got on diy-efi today so hopefully this is not too obnoxious a question. I have a '92 Nissan SE-R and would like to talk to the stock ECU. Has anyone reverse-engineered Nissan's interface, or are its specs available elsewhere? Nissan dealers have a 3K$ "Consult" computer to do this. I've seen cheap PC interfaces for GM systems. With specs, I think I can make a DOS machine interface, but need somewhere to start from. For a stock box, it's a nice hot-wire MAF SFI controller with 27lb injectors that should handle my needs... Thanks in advance for any information. -Wayne Cox wcox@xxx.com ------------------------------ From: FIScot@xxx.com Date: Tue, 30 Jan 1996 22:31:15 -0500 Subject: Re: Sensor Questions? Subj: re: Re: Sensor Questions? Date: 96-01-30 19:26:41 EST From: SRavet@xxx.com > Interesting, Scot. It doesn't seem that there is really a need for a > MAF, then. Is MAF just an aid to enable the CPU to learn better? Or > is there a MAF term in the fuel equation? Right, the MAF term was included in the right hand part of the equation. The MAF is the primary input the cpu considers for injecting fuel. The BLM is a correction term. (MAF = Mass AirFlow sensor) Scot Sealander FIScot@xxx.com ------------------------------ From: robert dingli Date: Wed, 31 Jan 1996 14:39:29 +1100 (EST) Subject: Re: Re: Sensor Questions? > its hard to build a non microprocessor based fi system without > a maf ; think about it. > I disagree. It would be quite simple. The airflow into the ports per revolution is almost directly related to the manifold pressure for most engines with a relatively flat volumetric efficiency characteristic. A simple linear mapping between the MAP signal and the injection period with injection timed to occur once per revolution works well. Injection every ignition pulse tends to magnify the injector dead time non linearity. Low load conditions such as idle tend to be erratic since the injector pulse widths are close to injector cutoff. A close look at a typical speed density map will show a relatively constant characteristic as a function of rpm and a near linear dependence on the MAP value. FWIW, I installed an aftermarket speed-density system on the weekend and was able to tune the efi and distributorless ignition system to a driveable state within two minutes. Constant slope fuelling maps work very well. ('76 Celica, ~'87 3SG 2 litre, Wolf3D efi/ignition) - 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: jgn@xxx. Napoli) Date: Tue, 30 Jan 1996 18:21:14 -0500 Subject: RE: Commercial systems >My parameters are as follows: > > Small block Chevrolet motor (377 cu in) in flat-bottom V-drive boat > (2) AiResearch TO-4 turbos > Powerglide > Crank-driven ignition > Gasoline fuel with methanol enrichment at higher power levels (>5 >psig boost) > 6000 RPM maximum > WOW! How long is the boat? What does it weigh? What size prop are you spinning? Napoli ------------------------------ From: Land Shark Date: Tue, 30 Jan 1996 21:14:33 -0700 Subject: MAF vs. MAP Guys, a MAP system is no harder to DESIGN than a MAF system The difference is that a MAF system is much more flexible in the real world ... with a MAP system, you have a calculated map of the engines VOLUMETRIC EFFICIENCY, which is changed by things such as exhausts, etc ... you measure MAP, calculate air density, and with the rpm and VE know how much fuel you need ... If you change the SHAPE of the VE "map" of the engine, not even the EGO corrections (BLM for you GM'ers) will compensate completely, since the BLM cells are much coarser than the actual VE map ... only a few places will be actually "on" the rest, a bit off .. A MAF system measures actual air into the engine, and needs only minor corrections in general ... Jim Conforti Converting Flappers to HFM's and Speed-Density for racing use only ------------------------------ From: Craig Pugsley Date: Wed, 31 Jan 1996 15:49:37 +1100 (EST) Subject: Re: Re: Sensor Questions? > > its hard to build a non microprocessor based fi system without > > a maf ; think about it. > I disagree. It would be quite simple. The airflow into the ports per > revolution is almost directly related to the manifold pressure for most > engines with a relatively flat volumetric efficiency characteristic. > > A simple linear mapping between the MAP signal and the injection period > with injection timed to occur once per revolution works well. This is how (some??) microtech systems work. The steady state injection on time is only dependent upon the MAP value, not RPM apart from it triggering the timer (But when on boost there is some RPM compensation) This assumes that the VE is linear across the RPM scale. (But when on turbo/supercharger boost there is some RPM compensation). I presume that this means if the 'slope' is set at RPM of max VE, it will be richer than nessecary when the VE is lower. As long as this over-richness isn't hugely too much it should be OK > Injection every ignition pulse tends to magnify the injector dead time > non linearity. Low load conditions such as idle tend to be erratic since > the injector pulse widths are close to injector cutoff. Hence staged injectors eg in 13B turbos, due to wide fuelling requirements FWIW, the microtech is an analog unit with screwdriver adjustments. I'd suggest it's a reverse engineered L-jetronic (or similar) using readily available commercial parts, and a MAP instead of a trapdoor air flow sensor. It is the cheapest adjustable EFI computer available, at $800aus ($~600 us), but isn't as flexible as the programmable stuff (Haltech, Motec, Wolf etc). Cheers, Craig. Glossary :-) MAF = Mass Air Flow sensor (hot wire) MAP = Manifold Absolute Pressure sensor RPM = Revolutions per minute VE = Volumetric efficiency (how much air the engine can take in as a % of the engine capacity 13B = Mazda wankel engine FWIW= For what it's worth ------------------------------ End of DIY_EFI Digest V1 #27 **************************** 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".