DIY_EFI Digest Wednesday, August 4 1999 Volume 04 : Number 448 In this issue: RE: ECU7 / diy-efi development, Lots of EFI articles re: From Cranking to Idle request info motronic See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Tue, 3 Aug 1999 16:35:15 -0700 From: "Al Lipper" Subject: RE: ECU7 / diy-efi development, Lots of EFI articles I'm glad to hear you're getting started. > From: Chris Caloto [mailto:caloto@xxx.edu] > > Hi Al. > > Got your e-mail. > Thanks for your well thought out replies. > I've got enough information to get started. > > What I plan to do is study the software and > ECU6 / ECU7 hardware and then build a test > box as you described. I can then try > improving your learning algorithm. > Depending on my progress / how well things go > I will then think about getting a rust bucket > car to try to install the ECU6 or ECU7 on. > If not I will e-mail you my results as you suggested > and we can collaborate via e-mail. > > I've read on the diy_efi List that you have > ECU6 boards for sale for $30 some dollars. > Do you have any ECU7 boards for sale ? I do not yet have ECU7 boards - still working on getting them made. A number of people are interested in the ECU6 boards, but I think I'l have 1 or 2 left. I don't want to make any promises on the ECU7 boards since I have not built one yet - we'll have to wait and see. > Here's an I'm just curious question: > I read that you insist that the Oxygen > sensor must be the heated type. > If it's not heated does the system really crash/ > perform THAT badly ? > How about rotary engines ? > Rotary engines run so hot (by nature of their > design) that exhaust temps are 1600 - 1800 degrees > Fahrenheit (honest.) > Mazda doesn't use heated Oxygen sensors on the > rotaries that have EFI (to the best of my knowledge.) > Anyways, what's the deal with the heated Oxygen sensor ? Actually, they don't work at all. The EGO sensor needs to be heated to approx. 280C before it starts outputting ANY voltage. Unheated sensors are located in the exhaust manifold where the exhaust is hot enough to keep them at operating temp. Since we are putting them downstream, it must be a heated sensor. I know some are "more heated" than others. It is best to use one designed to be used a ways downstream (yes, I know they're expensive). Your questions have encouraged me to dig out my journal articled accumulated over years of EFI research. Perhaps they may save you some time in your research. Most of them are from the SAE proceedings, so I will just give their reference numbers. SAE number: 841297 (or C444/84) 840141 930856 800539 790143 770400 770401 840152 800164 930854 Also, check out: International Journal of Vehicle design, vol 8, num 2. 1987, p.49 Int'l journal of mech. engineering 1985, C221/85 (G. Fegler) Int'l journal of mech. engineering 1985, C245/85 (J.L. Pfeifer) IEEE control systems, June 1994, p.31 IFAC Control Science and Technology proceedings, Kyoto Japan, 1981, p.2161 (N. Endo, T. Fukui, et. al.) Note, I'm not positive of the exact title of what I have listed as "Int'l journal of mech. engineering", but it is somthing like that. I hope these help. Looking them up on ei-web compendex (or a similar academic engineering database might help. They used to have trial subscriptions at: http://www.ei.org/, but I think any decent university library should have one). I know how much work a thesis can be, so I hope this helps some. Good luck. Al ------------------------------ Date: Tue, 3 Aug 1999 19:54:47 -0700 From: "John Dammeyer" Subject: re: From Cranking to Idle Hi Phil, Great response. Thanks. I'ved add some more questions. >Date: Wed, 04 Aug 1999 03:28:28 +1000 >From: Phil Lamovie >Subject: Re: From Cranking to Idle.DIY_EFI Digest V4 #443 > >Hi All, > >The problem of Injection timing at cranking is one of engine requirements. > >The problem is not as it seems. The engine doesn't run on petrol it runs on >vapor. >When the engine is cold very little vaporization takes place in the cold >air stream. I thought one of the injector's jobs was to atomize the fuel though. > >In fact the only physics available to aid us is low pressure. Thus the >time to inject is during the exhaust stroke. This allows maximum time for >latent heat absorption and thus vaporization and allows for a vacuum build >up during intake as long a you can convince the customer to keep their foot >of the acc. pedal. Not a problem. Most cars instructions are to leave the throttle alone. On the Honda, there is a cold start system that increases the air flow so that it acts as if the throttle has been cracked a bit. However, we've removed that to save weight and a couple of extra coolent hoses that could crack or break at altitude. (This is an remanufactured engine turning a propellor on a hovercraft or aircraft). So we have to crack the throttle a little bit at startup. This has been the biggest obsticle to cold starting. If we open the throttle too far the MAP is wrong compared to RPM and mixture is off. > >You will need approx. 300% excess fuel to start the engine. This is due to >the partial vaporization of the fuel. A cranking engine often has HC >components in the exhaust of 50-60% raw fuel. Don't assume that the >compression of the air will supply sufficient heat as the pressure builds >up very late in the piece. And the dwell time at that temp is only a few >ms. Worse still if you get the A/F wrong you have just chilled your >combustion chamber with a dose of raw fuel. Makes it important to really >over fuel. > We've found that we do need that much extra fuel. We inject just after the intake valve starts to open and pulse width at cranking is about 6ms. Once the engine starts and while the engine is cold the warmup enhancement keeps the pulse width at about 3.5 to 4ms. Once warmed up it drops to 2ms at idle and the loop is closed because the O2 sensor is used for closed loop control. > >You can either multiple fire the injectors by dropping the input divisor or >simply have a table with very big numbers. You may still run out of pulse >width if your injectors are too small. (See Toyota for several hundred >million examples) they still fit cold start injectors in place with very >low winter temps. Yes. I'm somewhat worried about really cold temperatures. My problem is that on Vancouver Island we rarely drop below 0 C. However, the injector pulse width at starting is tied to engine coolent temperature and the pulse width is also tied to engine intake manifold air temperature so hopefully it should work when cold. We'll find out this winter. > >The aim of the game is to use the smallest injector possible that fulfills >the requirements. Often 85% duty cycle is the target. that is of course 85% >of 720 Deg. >or 612 Deg. Based on the last dynamometer run, we found we were at about 12ms at 6000RPM and pulling 111 HP and our goal is 125HP; We've been able to get over 250ft/lbs Torque. This, at a little less than 75% duty cycle. As I understand the reason for 'the name of the game' is to provide a smooth unloaded idle. Since we turn a prop idling at about 900RPM we have a little bit of a load so a slightly larger injector might keep me under 75%. (I have a hardware limitation on pulse widths longer than 75% if I plan my injection at low rpm for the intake stroke). > >Due to the acc of the engine 0 to 600 in 1 to 1.5 seconds the pulses must >be linked to the crank. This will ensure that there are no missed pulses. >This also means that the crank trigger event must result in an injectio n >event even if the output buffer has not been updated with a sensible rpm >measurement and thus in fact the ecu may not know how fast the engine is >tuning. And in fact I do that. I use a double Hall Effect Sensor buried under the CAM Shaft timing pulley so not only do I detect TDC for each cylinder but the pattern is such I know which cylinder since only one Hall Effect sensor changes at each TDC. > >Most manufacturers use a cranking table that cuts out at say 350 rpm. Below >that >each trigger pulse is greeted with the same ms injector output regardless >of vacuum.. Now that's a good idea. Just say the heck with MAP,Water Temp, Air Temp and Throttle position and inject at fixed value under about 350 to 500 RPM. > >If you hard link the events then it doesn't matter how fast the acc of the >engine really is. If the fueling is wrong it will simply acc more slowly. > >The clue is to use the micro to set up a timer/off event from the >instigation of injection. Yes. I do that too. >Your electric motor should not be able to unsync a magnetic trigger firing >a gate on a transistor. Though it would confound the heck out of an input >capture rpm reading >as it is using clock events to determine rpm. During cranking it would be >very late in it's determination. By the time it has worked out the rpm it >could be 200% wrong in >its phasing as the engine speed could more than double on a 1/4 revolution. > It doesn't unsync the injectors, since I tie injector on with the TDC of the intake stroke. What perhaps isn't working as well as I'd like is the mixture at cranking due to the high acceleration from cranking to idle. But you are right about figuring out RPM during that initial high acceleration moment from cranking to idle; doesn't work. >Hope this cures some headaches and creates many others. Yes, thanks again. I still have an issue of when to actually trip the injector on. I've seen carburated cars start after only a half a revolution although as they get older it usually takes a turn or two. This implies that the fuel leaving the carburator gets into the cylinder easily enough although a cold engine leaves lots on the intake manifold walls. Explains why intake manifolds have a hot water path in them and gobs of fuel are needed when first starting. 8-) But, injection is supposed to get rid of the need for a lot of the excess fuel because it's sprayed almost directly onto the intake valve. Spraying onto a closed intake valve when the engine is cold or just warming up doesn't seem logical for a low pollution fuel efficient engine. My SAAB 99 used to be multi-port injection with the K-Jetronic Bosch system that varied fuel flow via fuel pressure. Engine ran fine but had lousy altitude compensation and it had a cold start injector. My 900 is much more sophisticated with multi-port sequential and has the luxury of having a MAF but no cold start injector; runs fine at any altitude but I think the turbine helps a little there. 8-) My JEEP uses MAP but has to be cranked a while before starting and I don't think it has a cold start injector. If I knew where to tap into I could sync the scope on the TDC sensor and look at the fuel injection pulse to see when they do it. But, isn't the idle quite a bit rougher if injection were to be started on the POP part of the stroke. Obviously at high RPM and 85% duty cycle it no longer matters but in-between.... Thanks, John ------------------------------ Date: Wed, 4 Aug 1999 00:23:00 +0200 From: "TT" Subject: request info motronic Hy dear friends i'm a very enthusiast appassionated of engine i have a pocket programmer and my car is equipped with bosch motronic mp.3.2 system ecu i have read eprom 's file in a 27c256 and have a version demo of software to remapping eprom i have find map of injection and spark advance but i want understand if are in axis rpm or loaded and hex value how corresponding in spark advance and time of ignition? please help me and give me all info to motronic system i have build a 02 sensor led and have notated that at full load mixture is too rich about 0.8 0.9 v how can adjust it? where are table of mixture and injection and lambda system? with stechiometric air fuel can to improve horse power and torque? because with this mixture rich engine not very good ..... ciao and help me if you want a original file to study it ask me p.s. i'm interested to understand disassembler code utilizzing in ecu to modify ecu system scientif and not a groplingly!!! ciao and many regards giuseppe rossetti italy ------------------------------ End of DIY_EFI Digest V4 #448 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. 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