DIY_EFI Digest Sunday, August 15 1999 Volume 04 : Number 469 In this issue: Laptop Management New to DIY_EFI promedit/ecu files See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Sun, 15 Aug 1999 05:56:53 +1000 From: Phil Lamovie Subject: Laptop Management Try this for size. RPM = 5500 or 91.6 RPS or 32,999 degrees/sec. People live in days and hours engines live in degrees. In order to digitally plot 33,000 degrees to an accuracy of 1 degree you will need to have some very flexible timers. You are going to have to calculate RPM a minimum of 4 times per revolution otherwise your ignition timing will fall in a heap as the engine accelerates. If your rate of change is 2500 rpm/sec that is from 2500 to 5000 in one second ! Then the rate of change per rev is on average 7 degrees. If you wait until after the end of the revolution and then start your calculation you would be lucky to be within 12 -14 degree of MBT timing. The very first thing is to establish the task. What am I controlling and what are it's requirements. Is it a requirement that the system be of a certain standard ? Do you need closed loop for catalytic converter feeding or can it be dispensed with. Do you need one pressure sensor or two ? I wish someone would slap me with a solid answer on this as I feel it's still not firmly established what is going on. As much as every control engineer loves a closed loop. It is the solution that works the slowest. The sensor takes for ever to register a change. most brand new broadband sensors take 200 - 300 ms that's enough time to do 25 to 30 revolutions or 120 firing strokes without a clue. Most carbys can do as well if not better. Your system, if it is to inspire others, should be of a Linux vs M$ battle do better than the big companies not worse. > If I need to be able to control at 1 msec intervals then I would need to be > able to output at 1 kHz. I think I will require clever electronics in order > to address 8 injectors individually or in pairs (any ideas for this)? Would > I need a system with 8 digital outputs at 1 kHz each? The resolution for injector control is 0.01 ms or 10 micro seconds which ever comes sooner. The grouping of injectors is very much a peripheral issue compared to accuracy of the injection duration. If your engine performs 120 firing strokes without you updating the output buffer then 119 of them will have the wrong A/F ratio regardless of your target. The A/D on your load sensing should be updated a a minimum of once per combustion so as to give minimum accuracy. > If I was to control the ignition timing electronically, it would probably > be using a control to advance and retard the timing using a servo I can't think why an engineer would suggest such a thing. Maybe your pentium has a valve with a faulty heater element. Or perhaps the clock work spring in the computers dynamo power supply has run down ???? Nissan often uses 180 pulses per revolution to measure engine speed. Toyota 12/rev, Ford 8 /rev, GM 18/rev. Why would they bother if it could be done using the postal system. I know that this might sound a tad sarcastic but I'm desperately trying to bring you a couple of orders of magnitude closer to the problem. It is some what akin to me thinking that the "K" in my processor is dead because when I hit it on the keyboard it doesn't come out onto the screen. We both know that there are many many layers of software and hardware between the two events but I'm standing in the shop asking the repair man to put a new "K" in my chip. Once again please forgive my tone I'm just an aging fool with a bee in his bonnet Regards Phil Lamovie injec@xxx.au cogito ergo zoom ------------------------------ Date: Sat, 14 Aug 1999 23:25:52 +0300 From: Pekka Ripatti Subject: New to DIY_EFI Hi all. I've subscribed few days ago to this list and thought that you would like to know my aim. I'm a member of a Mileage Marathon -team in our school (Lappeenranta University of Technology, Finland), the team is named Tippa-Team. Our engine concept is quite simple - a 4 stroke, 42 cc, petrol (98 oct) powered, single cylinder engine ran for short periods at full throttle. The rule is that the average speed of one run is 25 km/h and one run is approx. 20 km of round track with standing start. We accelerate 35 km/h and turn off the engine. The vehicle (named Titanic Sauna) then rolls and at 17 km/h (or so) we start the engine again (with a motorbike's electric starter) and accelerate to 35 again. This goes on until the last lap, where the aim is to have close to no speed at the finish line. We are planning to build a completely new engine and it would be challenging (and awarding) to build our EFI, because commercial applications aren't too well suited for this use. for more info see http://www.ltky.lut.fi/org/tippateam/Englanti/vehicle.html ------------------------------ Date: Sat, 14 Aug 1999 20:24:43 EDT From: Mikepoore@xxx.com Subject: promedit/ecu files I am curious as to what compatibility lies in the ecu files used with promedit. Someone please correct me if I am wrong, but aren't the table locations going to be the same for any 256k eprom out of a '727 ecm regardless the GM application. The thing I was confused about is that I thought that 727's were used on both TPI and TBI applications. Does this change table locations, sizes, and definitions? I guess what I am asking is would an ecu file for a 727 TBI system work for a 727 TPI system? Mike Poore ------------------------------ End of DIY_EFI Digest V4 #469 ***************************** 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".