DIY_EFI Digest Thursday, February 17 2000 Volume 05 : Number 065 In this issue: Re: Mixture measurement using Lamda and EGT IGBT's Mass airflow sensors. Re: Mass airflow sensors. RE: Mass airflow sensors. RE: EFI Re: Mass airflow sensors. Re: Mass airflow sensors. Re: Mass airflow sensors. Re: Mass airflow sensors. RE: Mass airflow sensors. Parallel Port Interface DIS and the MC3334? See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 16 Feb 2000 07:25:50 -0700 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: Mixture measurement using Lamda and EGT At 1:03 PM 2/15/00, Ade + Lamb Chop wrote: >Hi All, > >This has sort of thing has been basically covered recently however. What is >the principal behind it? > >I understand about Lamda sensors and how they are so nonlinear that not >very far off of Lamda 1 is in the region of full rail. I also understand >that the EGT goes up with a lean mixture and down with a rich mixture. Actually, EGT peaks at lambda = 1, drops going to either the rich or the lean side. Combustion flame temp is always hottest at lambda = 1. > Greg - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 16:20:12 -0500 From: "Vitek, Joseph" Subject: IGBT's Have you looked at International Rectifier's IGBT's and their HEXFET Power MOSFET's? They have a lot of good parts for applications just like ours. http://www.irf.com Check it out. Joe --------------------------------------------- He who trades necessary liberty for temporary security deserves neither liberty nor security. -Benjamin Franklin- >Date: Wed, 16 Feb 2000 10:18:21 -0000 >From: "Rich M" >Subject: RE: MC3334 based ignition > >Hi Guys, >A normal bipolar would have Vce(sat) around 0.7V, but not a darlington! >MJ10012 quotes Vce(sat)=2V at Ic=6A, Ib=0.6A and Vb=2.5V - that's 1.6Watts >dissipation just for base drive! > >How about a IGBT? Look at Motorola MGP20N40CL - Vce=400V (internally >clamped), Ic=20A cont. Vce(sat)=1.8V max.(at 10A) Gate drive is like a >logic-level mosfet ie. guaranteed fully on at TTL logic high(min) level, >gate current is statically negligible, but highish gate capacitance requires >a reasonably stiff drive for high speed switching. The gate is zener clamped >to avoid damage from voltage spikes. >This device was designed for coil switching and all in a TO220 package >style. >www.mot-sps.com for details. >Hope this helps. > >Rich > - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 15:25:58 -0800 From: "Andrew Brownsword" Subject: Mass airflow sensors. Hello again, I am looking at how to replace my car's stock airflow sensor (a VAF, or vane airflow sensor) with some other kind. I've worked out most of the logic changes that are required in the ECU. The main reason for doing this is the highly non-linear nature of the VAF's output -- at high airflow rates the device saturates and large airflow changes results in tiny voltage changes. One possibility is a device made by Link Technologies called the Link AFM. It is a computer with a MAP sensor and an RPM interface that generates a voltage signal that can be hooked to the stock ECU's airflow input. It is programmable, allowing extensive tuning. Its also expensive, and Link won't part with an information about the shape of its output curve. The other possibility is to install a MAF. Unfortunately I know almost nothing about MAF's and their output characteristics, and that is why I'm writing to the list... If I use a MAF, should I just ignore the IAT input? What kind of MAF should I use, and where should I get it from? What are their output voltage curves like? What kind of processing should I do on the value from the MAF, or can I just convert it straight into the internal airmass representation? What level of boost can a MAF sense? (my car has an aftermarket turbo, which is the whole reason for doing this). Thanks, Andrew - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 18:58:50 -0500 From: "nacelp" Subject: Re: Mass airflow sensors. > The other possibility is to install a MAF. Unfortunately I know almost > nothing about MAF's and their output characteristics, and that is why I'm > writing to the list... Two very different types of GM MAFs, voltage output or frquency. Rated by grams per second. You'd need to match applications for getting one about the same flow range as what you need. > If I use a MAF, should I just ignore the IAT input? ??. MAFs measure Mass Air Flow, which automatically means it, compensates for temp.. What kind of MAF should > I use, and where should I get it from? You have to figure what you need before you need to find where to get it. What are their output voltage curves > like? What kind of processing should I do on the value from the MAF, or can > I just convert it straight into the internal airmass representation? One of the Ford guys had some flow bench numbers at the ford ecu list, no I don't have a URL. What > level of boost can a MAF sense? (my car has an aftermarket turbo, which is > the whole reason for doing this). MAFs don't care about boost just how much air is flowing thru em. The trick is getting the fuel calibration right. Might try reading some more in the archives, about MAFs MAPs etc Grumpy > > Thanks, > Andrew > > > > -------------------------------------------------------------------------- - -- > To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) > in the body of a message (not the subject) to majordomo@xxx.org > - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 16:11:32 -0800 From: "Buchholz, Steven" Subject: RE: Mass airflow sensors. Well, it seems to me that you could hook the MAP sensor up to your car and hook up a data collection system that included information about the "VAF", MAF and tach inputs which should give you the necessary transfer functions. Once this info was available it should be a simple matter to create a computer that would take the MAF and tach inputs and output the simulated VAF. AAMOF, one could design a computer that "learns" the transfer functions by accepting the VAF, MAF and RPM inputs in a learn mode. This is probably why Link is tight lipped about what they do. The thing that makes me wonder why you would even want to do this is that the ECU to which the VAF is attached is calibrated to the characteristics of the VAF. It is expecting that small signal change for a given change in flow at high rates. What do you expect to accomplish with this mod? Please don't take this message as being a flame ... I'm working with limited information here ... I don't even know what kind of car we are discussing here. If you were talking about reprogramming the maps in the ECU then this sort of swap might make a lot more sense ... and might make it possible to simplify things. Many ECUs already have an independent RPM input that becomes one of the input variables to the fuel/timing maps. If you know how the inputs are processed to access the maps it seems to me that it should be completely possible to hook the MAP sensor directly to the input to the ECU and account for the differences in the behavior of the two signals by simply programming the map appropriately. You will probably still need to do some experimentation to determine the different behavior of the VAF vs MAP sensors. Good luck with your project! Steve Buchholz San Jose, CA (USA) > -----Original Message----- > > I am looking at how to replace my car's stock airflow sensor (a VAF, or vane > airflow sensor) with some other kind. I've worked out most of the logic > changes that are required in the ECU. The main reason for doing this is the > highly non-linear nature of the VAF's output -- at high airflow rates the > device saturates and large airflow changes results in tiny > voltage changes. > > One possibility is a device made by Link Technologies called the Link AFM. > It is a computer with a MAP sensor and an RPM interface that generates a > voltage signal that can be hooked to the stock ECU's airflow input. It is > programmable, allowing extensive tuning. Its also expensive, and Link won't > part with an information about the shape of its output curve. - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 16:32:35 -0800 From: "Al Lipper" Subject: RE: EFI Actually, I've sold all the ECU6 boards I have. The plans are available online, but I'm not currently in the business of selling kits. In the future, I may have some ECU7 boards to sell, but I'm not sure of that at this time. Al > -----Original Message----- > From: RSRACE@xxx.com] > Sent: Wednesday, February 16, 2000 10:00 AM > To: efi@xxx.com > Subject: EFI > > > Are you selling the systems complete and assembled? Or are you > selling the > boards and parts still. > > Thanks > Tom > - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 16:57:57 -0800 From: "Andrew Brownsword" Subject: Re: Mass airflow sensors. >> The other possibility is to install a MAF. Unfortunately I know almost >> nothing about MAF's and their output characteristics, and that is why I'm >> writing to the list... > >Two very different types of GM MAFs, voltage output or frquency. Rated by >grams per second. You'd need to match applications for getting one about >the same flow range as what you need. I need a voltage output in the range 0..5v. The car's flow rate limit is about 360 cfm at my target boost level (I think... I don't have my tables in front of me, and its been a bad day), so a device that read 5v @ 400 cfm should give enough of a buffer zone. >> If I use a MAF, should I just ignore the IAT input? >??. MAFs measure Mass Air Flow, which automatically means it, compensates >for temp.. Thats what my thinking is... but I don't know much about MAF's so I don't know if a bit more compensation might be required? The ECU in its original condition uses the VAF, IAT and Baro readings to calculate airmass. > What kind of MAF should I use, and where should I get it from? > >You have to figure what you need before you need to find where to get it. Good point, but what are my options? > What are their output voltage curves >> like? What kind of processing should I do on the value from the MAF, or >can >> I just convert it straight into the internal airmass representation? > >One of the Ford guys had some flow bench numbers at the ford ecu list, no I >don't have a URL. Pity... does anyone else out there have flow bench numbers of this sort, or the URL to this page? Search engines these days don't seem to be worth a hill of beans -- I've been trying all sorts of different searches with no luck. But then it has been a bad day. > What level of boost can a MAF sense? (my car has an aftermarket turbo, which is >> the whole reason for doing this). > >MAFs don't care about boost just how much air is flowing thru em. The trick >is getting the fuel calibration right. No doubt -- but I've got a Techtom and a dyno for this. >Might try reading some more in the archives, about MAFs MAPs etc Good idea, thanks. Andrew - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 17:25:31 -0800 From: "Andrew Brownsword" Subject: Re: Mass airflow sensors. >Well, it seems to me that you could hook the MAP sensor up to your car and >hook up a data collection system that included information about the "VAF", >MAF and tach inputs which should give you the necessary transfer functions. >Once this info was available it should be a simple matter to create a >computer that would take the MAF and tach inputs and output the simulated >VAF. AAMOF, one could design a computer that "learns" the transfer >functions by accepting the VAF, MAF and RPM inputs in a learn mode. This is >probably why Link is tight lipped about what they do. Yes, no doubt... but I'm still a little annoyed with them. I offered to sign an NDA or whatever... and all I want is the rough shape of their output curve, i.e. "linear" "parabolic" "1/x^2". From there I could tune using their interface. >The thing that makes me wonder why you would even want to do this is that >the ECU to which the VAF is attached is calibrated to the characteristics of >the VAF. It is expecting that small signal change for a given change in >flow at high rates. What do you expect to accomplish with this mod? Please >don't take this message as being a flame ... I'm working with limited >information here ... I don't even know what kind of car we are discussing >here. No problem, I appreciate any help you can give. The car is a 1993 Ford Probe GT, 2.5L DOHC V6 with an aftermarket turbocharger. The initial problem is that the stock injectors are rather anemic and can't support over about 3psi of boost using an FMU (spray pattern goes completely to kak at >80psi). To solve this I bought a set of high flow injectors from VENOM -- unfortunately they might be a little TOO high flow (350 cc/min, I bought them while under the delusion that the stock rate was 220 cc/min, now I have strong reasons to believe they are closer to 180). So... I've reverse engineered enough of the ROM to figure out how to recalibrate for the injector flow rate. The main sticking point could be getting the car to idle nicely, but I won't know that until I try and it depends on what the minimum practical on-time for the injectors is. Now, assuming that I get the injectors working properly, I need a plan to get the pulse widths up when confronted by a higher airflow. Problem #1 is that ECU's programming has an explicit limit built into it based 1 atmosphere. Problem #2 is that the VAF generates a voltage based on (1 / airflow^2 )... which results in a nearly vertical slope at high airflows. I've followed the logic from the reading of the VAF input voltage through to the fuel logic, and there don't seem to be any other issues. Problem #1 I can just remove -- I'm pretty sure the reason it is there is because of the slop in the VAF at high airflows. Problem #2 is solved by a new airflow meter, hence my question to the list. > If you were talking about reprogramming the maps in the ECU then this >sort of swap might make a lot more sense ... and might make it possible to >simplify things. Many ECUs already have an independent RPM input that >becomes one of the input variables to the fuel/timing maps. If you know how >the inputs are processed to access the maps it seems to me that it should be >completely possible to hook the MAP sensor directly to the input to the ECU >and account for the differences in the behavior of the two signals by simply >programming the map appropriately. You will probably still need to do some >experimentation to determine the different behavior of the VAF vs MAP >sensors. The RPM is factored into the equation in the ECU because the VAF measures CFM and the ECU wants essentially "airmass per revolution". I do want to simplify as much as possible, and ROM space is limited... which is why I have essentially ruled out using a MAP sensor directly. A speed/density system needs to have a pressure/RPM map, and I don't have the space to implement that, nor the debugging facilities to make it work! A MAF sensor, on the other hand, generates an input similar in nature to the VAF -- except that the curve is replaced by some kind of almost-linear ascending function that already incorporates air temperature and humidity. Whew. So... now that I've given you the whole spiel, do you have any thoughts? Am I completely insane, or is this just the kind of challenge you guys love. :) Andrew PS: we've been around and around and around on getting the fueling on this car right, and this is the best direction we've got. Aftermarket parts for it are fairly rare, and a replacement ECU is very expensive and doesn't have all the nice features of the stock ECU (i.e. emissions control and 1 O2 sensor feedback loop per bank of 3 cylinders). - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 20:49:55 -0500 From: "nacelp" Subject: Re: Mass airflow sensors. If your as sharp as you sound, I'd run a map sensor, and plot a bunch of points and compare them to the VAF. Then use a pic to translate things, it would need a rpm input and IAT to get things right, and would be involved, but sounds like you have lots of work to do here, anyway to get this right. Grumpy What kinda of signal does your TPS output?. How many wires on your IAC?. > Whew. > So... now that I've given you the whole spiel, do you have any thoughts? Am > I completely insane, or is this just the kind of challenge you guys love. > Andrew PS: we've been around and around and around on getting the fueling on this > car right, and this is the best direction we've got. Aftermarket parts for > it are fairly rare, and a replacement ECU is very expensive and doesn't have > all the nice features of the stock ECU (i.e. emissions control and 1 O2 > sensor feedback loop per bank of 3 cylinders). - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 18:46:47 -0800 From: "Andrew Brownsword" Subject: Re: Mass airflow sensors. Heh, I hope I'm that sharp. But I'm a software guy, so I'd prefer a software solution and building a PIC isn't something I want to get into if I can help it. The ECU has the right number of inputs as it is, and has nice calibrated RPM, IAT, TPS, and Baro readings. If I get a set of voltage vs. airflow readings for the MAF I'm going to use, then I can start from there and tune the new table I'll put in place of the VAF table. Plenty of room for that, and the code is trivial (uses existing subroutines). A full pressure vs. RPM map would want to be pretty big and would take longer to tune... I'd guess that I have room for about a 15x10 entry map of 1 byte entries, and that doesn't seem like enough. Yeah, its going to take work... but that the whole point of a project car, isn't it? Thanks, Andrew - -----Original Message----- From: nacelp To: diy_efi@xxx.org> Date: Wednesday, February 16, 2000 5:56 PM Subject: Re: Mass airflow sensors. >If your as sharp as you sound, I'd run a map sensor, and plot a bunch of >points and compare them to the VAF. Then use a pic to translate things, it >would need a rpm input and IAT to get things right, and would be involved, >but sounds like you have lots of work to do here, anyway to get this right. >Grumpy > What kinda of signal does your TPS output?. > How many wires on your IAC?. > >> Whew. >> So... now that I've given you the whole spiel, do you have any thoughts? >Am >> I completely insane, or is this just the kind of challenge you guys love. >> Andrew > PS: we've been around and around and around on getting the fueling on this >> car right, and this is the best direction we've got. Aftermarket parts >for >> it are fairly rare, and a replacement ECU is very expensive and doesn't >have >> all the nice features of the stock ECU (i.e. emissions control and 1 O2 >> sensor feedback loop per bank of 3 cylinders). > > >--------------------------------------------------------------------------- - - >To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) >in the body of a message (not the subject) to majordomo@xxx.org > - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Thu, 17 Feb 2000 06:38:21 +0100 From: =?iso-8859-1?Q?J=F6rgen_Karlsson?= Subject: RE: Mass airflow sensors. There is a box called IFT from Perfect Power in South Africa, it is designed to modify up to two sensor signals and/or one ignition trigger timing. One of the two versions has a built in MAP sensor, I haven't checked but I guess that it could be used to simulate the air flow sensor. The manual and software is available on the web. Check it out at http://www.perfectpower.co.za/ift1.htm I don't know the price, but their other stuff is very inexpensive. The turbo fueller is great, modifies ignition timing and drives a bunch of additional injectors for only4 $200. Jörgen - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Wed, 16 Feb 2000 23:34:03 -0800 (PST) From: Chris Wilkinson Subject: Parallel Port Interface Hi I am new to the list (joined this weekend). my name is Chris Wilkinson, and I am very interested in all types of fuel injection projects. My particular project is to build a PC based fuel injection system, to be developed around one of my race bike engines. These engines are 250cc 2-stroke engnies which produce 45-50 H.P. @xxx. This project is not meant for any particular purpose except that of my further education. my engine only needs one injector (1 cylinder) and I would like to run it from a parallel port. My limited knowledge of this subject gives me the inclination to develop a C or C++ coded piece of software which can send a Puls Width Modulation signal out the first data pin on a parallel port. I would amplify this (using a switching transistor) to 12v to directly control my injector. I also need to devise a way (probably using an Analog/Digital Conv.) to read my MAP sensor and Temp sensor. I can use my existing digital ignition pulse generator to read RPM. Using these sensors and my stock carb I hope to create a 4 Dimensional table (MAP*Temp*RPM*TPS) for lookup table type injection. then replace the carb with a Throttle body and injection manifold. few... with all that said I am looking for any suggestions on how to amplify the injector signal from the parallel port, and how to convert the sensor analog data (MAP TEMP TPS) to usable digital data. Also I am not much of a programmer so Is there anyone who can tell me how to code (C or assembler in a DOS environment) to modulate my injector signal. I also thought of using a sound card or USB to modulate the signal. If any of you can help me or steer me straight I would be very greatfull. __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Thu, 17 Feb 2000 09:25:19 +0100 From: =?iso-8859-1?Q?J=F6rgen_Karlsson?= Subject: DIS and the MC3334? I saw one thing about the 3334, the compensation for low voltage when cranking. It is plenty of time for it to fade out on a V8 with distributor. Running at around 50Hz ignition frequency at idle, but on a waste spark dis with the same idle it is only aound 13-14hz. I can't use waste spark on my car, five cylinders. At idle, 1000rpm, I get only 8.3Hz. Does someone know what the typical on time will be at 14v and 8.3Hz? I think that it will give me trouble, what do you guys think? Is the fading out of the low voltage compensation enough to let my car idle without huge heat sinks on the drive transistors? Jörgen Karlsson Gothenburg, Sweden. - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ End of DIY_EFI Digest V5 #65 **************************** 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".