DIY_EFI Digest Wednesday, 19 June 1996 Volume 01 : Number 171 In this issue: 1/4 Wave Tuning Re: Anybody build their own 5th wheel? Re: 1/4 Wave Tuning Re: Anybody build their own 5th wheel? AFR control Re: AFR control Re: 1/4 Wave Tuning Re: Anybody build their own 5th wheel? Diesel EFI oxygen sensor Re: Diesel EFI Re: Home-grown 5th wheel project [none] Re: oxygen sensor Re: Home-grown 5th wheel project Re: AFR control See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Donald Whisnant Date: Tue, 18 Jun 1996 09:42:32 -0400 Subject: 1/4 Wave Tuning Hi guys... Does anyone know the exact reason for the "1/4 wave tuning" modules (or that is what GM shop manual calls them) on the intakes of a lot of vehicles?? It appears to me that it is just an extra box or chamber in between the air filter and the throttle body ... My Formula Firebird has one as well as most SFI and CMFI injected pickups and vans) ... My only guess is that it is a method of "tuning the intake" kind of like length tuning of exhausts... My next question is how is it's volume calculated? 1/4 wave of what? How much extra horses does it produce (if any)? Also, does the shape matter? My Firebird has a round one mounted vertically between the two cooling fans... The vans and trucks that I've seen with them have more of a square box mounted at the top (toward the inside) of the radiator... ... Can anyone answer these questions?? (or has anyone even looked at or thought about it? -- as I never noticed until I was hooking up a CMFI 4.3 engine that came out of a van into my '85 Grand Prix and noticed it in several diagrams of the GM shop manual) ... Thanks... Donald Whisnant dewhisna@xxx.com ------------------------------ From: Steve Powers Date: Tue, 18 Jun 1996 08:27:35 -0700 Subject: Re: Anybody build their own 5th wheel? Orin suggests: > Why not use a bicycle computer pickup - a magnet (or however many you want) > bolted to the spokes and the pickup coil bolted to the wheel's mount? > > Orin. further to that, get an Avocet magnet ring and sensor. The Avocet provides 20 pulses per revolution in the form of a analog signal. Just go to any decent bicycle store and ask for a mounting kit for an Avocet 50 computer. You will get the sensor and magnet ring for about $10. - -- steve powers stratos product development group spowers@xxx.com seattle, washington ------------------------------ From: Gary W Harris Date: Tue, 18 Jun 96 08:46:00 PDT Subject: Re: 1/4 Wave Tuning Text item: I think tghis may be used for noise suppression (in the case of Vans) or noise ("sound") enhancement in the case of a Firebird. Need to get that distinctive power sound, a fair amount of which orginates from the intake system. Gary Hi guys... Does anyone know the exact reason for the "1/4 wave tuning" modules (or that is what GM shop manual calls them) on the intakes of a lot of vehicles?? It appears to me that it is just an extra box or chamber in between the air filter and the throttle body ... My Formula Firebird has one as well as most SFI and CMFI injected pickups and vans) ... My only guess is that it is a method of "tuning the intake" kind of like length tuning of exhausts... My next question is how is it's volume calculated? 1/4 wave of what? How much extra horses does it produce (if any)? Also, does the shape matter? My Firebird has a round one mounted vertically between the two cooling fans... The vans and trucks that I've seen with them have more of a square box mounted at the top (toward the inside) of the radiator... ... Can anyone answer these questions?? (or has anyone even looked at or thought about it? -- as I never noticed until I was hooking up a CMFI 4.3 engine that came out of a van into my '85 Grand Prix and noticed it in several diagrams of the GM shop manual) ... Thanks... Donald Whisnant dewhisna@xxx.com Text item: External Message Header The following mail header is for administrative use and may be ignored unless there are problems. ***IF THERE ARE PROBLEMS SAVE THESE HEADERS***. Reply-To: diy_efi@xxx.edu Precedence: bulk Sender: owner-diy_efi@xxx.edu Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii References: <199606180900.JAA23180@xxx.edu> Subject: 1/4 Wave Tuning To: diy_efi@xxx.edu MIME-Version: 1.0 X-Mailer: Mozilla 2.01 (X11; I; SunOS 4.1.3_U1 sun4c) From: Donald Whisnant Date: Tue, 18 Jun 1996 09:42:32 -0400 Message-ID: <31C6B248.2781E494@xxx.com> Received: from splinter by atl.lmco.com (8.6.13/ATL 1.14) with SMTP id JAA03856; Tue, 18 Jun 1996 09:42:33 -0400 Received: from atl.lmco.com (hannibal.ATL.LMCO.COM [166.20.244.250]) by franklin .vf.lmco.com (8.7.5/8.7.3) with SMTP id JAA13594; Tue, 18 Jun 1996 09:42:34 -040 0 (EDT) Received: from franklin.vf.lmco.com (franklin.vf.lmco.com [166.17.5.51]) by deka lb.vf.mmc.com (8.7.5/8.7.3) with ESMTP id JAA24277; Tue, 18 Jun 1996 09:42:36 -0 400 (EDT) Received: from dekalb.vf.mmc.com by coulomb.eng.ohio-state.edu via ESMTP (940816 .SGI.8.6.9/940406.SGI) for id JAA24328; Tue, 18 Jun 1996 09:4 2:36 -0400 Received: by coulomb.eng.ohio-state.edu (940816.SGI.8.6.9/940406.SGI) id NAA24333; Tue, 18 Jun 1996 13:42:40 GMT Received: from coulomb.eng.ohio-state.edu (coulomb.eng.ohio-state.edu [128.146.9 0.150]) by ormail.intel.com (8.7.4/8.7.3) with SMTP id IAA15942 for ; Tue, 18 Jun 1996 08:37:51 -0700 (PDT) Received: from ormail.intel.com (ormail.intel.com [134.134.248.3]) by relay.jf.i ntel.com (8.7.4/8.7.3) with ESMTP id IAA15667 for ; Tue, 18 Jun 1996 08:37:51 -0700 (PDT) Return-Path: owner-diy_efi-outgoing@xxx.edu ------------------------------ From: ptimmerm@xxx.GOV Date: Tue, 18 Jun 1996 08:52:46 -0700 Subject: Re: Anybody build their own 5th wheel? I have sent away for an electronic fifth wheel. Sort of anyhow. This unit, G-Tek Pro for $139 has micro accelerometers. Program in weight and it gives 0-60 acceleration times, 60-0, 1/4 miles, instantaneous horsepower at rear (front, all) wheels, and lateral acceleration. I can report how well it works in a couple of weeks. paul timmerman ------------------------------ From: eric_e@xxx.com (Eric Elliott ) Date: Tue, 18 Jun 1996 09:30:46 -0700 Subject: AFR control Hello, Having read so much mail about wanting a linear exhaust gas sensor, I considered how to do with what we have. Could be an original thought or maybe this is in a book I haven’t read yet, but here goes.... Maybe the HEGO could be used at stoich to get the correct non-stoich AFR. Given: We need accurate air/fuel ratio (AFR) control over a wide range of AFR’s. The HEGO is accurate only at stoich. Accurate direct linear AFR measurement is expensive and shortlived. Volumetric efficiency varies wildly with RPM, throttle opening, weather, temperature, etc. Engines can’t sustain operation at high load and stoich AFR. Maybe: Starting with conservative (rich) fuel fuel table values, the 332 could determine in a few power cycles the injection duration needed to get stoich (get a useable stoich output from the HEGO), then return to the conservative (rich) fuel fuel table value. Desired AFR could then be calculated from the stoich value, and the original fuel table value altered. Restated, the engine could, at a given RPM & load, be switched to operation at near stoich for a few cycles, then returned to safe rich operation. After a few trials, stoich operation could be measured via the HEGO, then accurate calculation of the desired fueling could be done. In economy cruise this could be easy and risk free. At max effort, to avoid engine damage, the 332 would have to severely limit consecutive cycles near stoich. If the stoich determination is done on a cylinder by cylinder basis, the momentary (V8) power deviation would be much less than a 6% power loss at worst. At the same time, individual cylinder & injector matching data could be collected. Arbitrary open loop fuel table values could be replaced by ideal values without extensive dynamometer time. The 332 could always be refining the fuel table values. Is this a workable AFR control procedure? Eric ------------------------------ From: MSargent@xxx. Sargent) Date: Tue, 18 Jun 1996 13:22:59 -0400 Subject: Re: AFR control > Engines cant sustain operation at high load and stoich AFR. I don't think this statement is correct. You certainly don't want to go lean at WOT, but stoich should be OK. Normally you run rich at WOT to get more power. Stoich is a 14.7:1 A/F ratio, and max power is around 12:1 AFR. +--------------------------------------------------------------------------+ | Michael F. Sargent | Net: msargent@xxx.com | Phone: 1(613)721-0902 | | Gallium Software Inc.| | FAX: 1(613)721-1278 | +--------------------------------------------------------------------------+ ------------------------------ From: Chuck Tomlinson Date: Tue, 18 Jun 1996 14:05:41 -0400 Subject: Re: 1/4 Wave Tuning Donald wrote: > >Does anyone know the exact reason for the "1/4 wave tuning" modules (or that is >what GM shop manual calls them) on the intakes of a lot of vehicles?? It appears >to me that it is just an extra box or chamber in between the air filter and >the throttle body The module is called a Helmholtz resonator, and its primary (I think only) purpose is noise reduction near a particular frequency. >... My Formula Firebird has one as well as most SFI and CMFI >injected pickups and vans) ... My only guess is that it is a method of "tuning >the intake" kind of like length tuning of exhausts... My next question is how is >it's volume calculated? 1/4 wave of what? How much extra horses does it >produce (if any)? Also, does the shape matter? According to the Bosch Automotive Handbook, Volume = (Sm/l)*(c/omega)^2, where Sm = avg. cross-section area of the runner l = runner length c = speed of sound in air omega = resonant frequency = 2.pi.f, for f in Hz. AFAIK, it adds no power (maybe reduces power slightly), and the shape does _not_ matter. I don't know why the GM manual calls them "1/4 wave" modules, because the volume (not the length) is the important parameter for a Helmholtz resonator. Chuck Tomlinson tomlinsc@xxx.com ------------------------------ From: orin@xxx.com (Orin Eman) Date: Tue, 18 Jun 1996 11:16:13 -0700 (PDT) Subject: Re: Anybody build their own 5th wheel? > further to that, get an Avocet magnet ring and sensor. The Avocet provides > 20 pulses per revolution in the form of a analog signal. Just go to any > decent bicycle store and ask for a mounting kit for an Avocet 50 computer. > You will get the sensor and magnet ring for about $10. Have you used an Avocet recently? I used to have one and it didn't work very well, had Audi battery contacts I think, I had to wedge bits of paper in there to make sure it didn't lose power. Orin. ------------------------------ From: Pete Sterrantino Date: Tue, 18 Jun 1996 16:23:08 -0400 (EDT) Subject: Diesel EFI I have recently joined these mailing lists (diy-efi and efi-332) and am learning a great deal about EFI. I currently work with 68HC11 and 68332 based controllers and am looking to develop an EFI system for a large (about 3000 HP), fixed-speed, turbocharged diesel. I have joined the SAE, collected a series of papers and books, including several from Bosch, and attended a couple of seminars. I have picked up quite a bit, but several core questions remain unanswered. I may be barking up the wrong tree, but am hoping someone on the list can answer or at least point me in the right direction. I do not understand the generation of the fueling maps. I understand I can use PV=nRT to calculate the amount of air (or O2) being inducted, but how does that correspond to the amount of fuel used? What is (are) the correct A/F (or O2/F) ratios for diesel engines of this type? Secondly, in a fixed speed engine, fuel consumption varies with load. If I am applying this correctly, and a fixed RPM corresponds to a certain volume/stroke, how is load accounted for? Do you just add more fuel up to a certain limit? Is this linear? I have tried to "cheat" and get the answers to these questions by determining the amount of fuel injected by a mechanical injector over the full stroke range, however, this information is not easy to get. I would also like to be able to back up any calculational values with real injector data and vice-versa. Any suggestions? Thanks in advance. Pete Sterrantino email: sterrant@xxx.com ------------------------------ From: "Zublin, Bryan (SD-MS)" Date: Tue, 18 Jun 1996 13:19:00 -0700 (PDT) Subject: oxygen sensor ---------- From: toyota-mods-owner To: Craig A Terlau Cc: Daucott; mr2-digest; Toyota-mods Subject: oxygen sensor Date: Tuesday, June 18, 1996 3:35PM Here's one for the fuel injection experts. I'm presently running in my fuel injected turboed 18RG (without the turbo till the head gets retensioned) and i would like to run an O2 sensor, firstly to help tuning and secondly as a warning of lean outs at high boost. Apparently single wire sensors only last about a week when using leaded fuel as they get lead coated at low exhaust temps. Someone suggested that the 3 wire sensors (which are heated) may last longer. Has anyone tried this or know if it has been sucessfully used in a leaded fuel car. Cheers, ~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~ Justen Simpson simpson@xxx.au CRC for Freshwater Ecology, Uni of Canberra, Australia ~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~ ------------------------------ From: MSargent@xxx. Sargent) Date: Tue, 18 Jun 1996 16:40:15 -0400 Subject: Re: Diesel EFI > What is (are) the correct A/F (or O2/F) ratios for diesel engines of this type? You've got it easy. Diesel engines don't really care about an A/F ratio. You just put in all the air you can (most normally aspirated diesels don't even have a throttle), and add as much diesel fuel as needed to produce the amount of power needed. The A/F ratio is not important, only the amount of fuel and the power desired. Given this, you'll see that a two bit governor which adds more fuel as the engine speed drops, and less as it overspeeds, is sufficient for most fixed speed applications. Naturally you'll want to use a micro, and a whole bunch of sensors, but you can build a perfectly good mechanical system for a lot less. +--------------------------------------------------------------------------+ | Michael F. Sargent | Net: msargent@xxx.com | Phone: 1(613)721-0902 | | Gallium Software Inc.| | FAX: 1(613)721-1278 | +--------------------------------------------------------------------------+ ------------------------------ From: ws6transam@xxx.net (Daniel R Burk) Date: Tue, 18 Jun 1996 21:20:31 -0400 (EDT) Subject: Re: Home-grown 5th wheel project Thanks Bruce, Orin, Dan and Peter for the wonderful input. I'll zip over to the bicycle shop and get an idea of what the mag pickup looks like. I might be able to do just as you suggested and mount a small magnet onto every other spoke. There seem to be approx. 36 spokes on a typical wheel so that would be 18 positions which is one every twenty degrees. Based on my initial calculations using 36 spokes on a 26 inch O.D. tire/rim combo, I would get a 1000 Hz signal at approx. 129 MPH. Thus, with only 18 spokes, I should get a 500 Hz signal. I did a quick check on how much time a .100" thick spoke would break my light beam if I was monitoring near the edge of the rim. (20.5" dia.) I found that the spoke would obstruct the beam for only 60 microseconds at 129 MPH!! I'd have to widen that pulse width by either using a 1 shot timer, or by moving the sensor closer to the hub. The research continues. BTW, I like the idea of correlating the data via integration of the accelerometer data. I'll probably load it all into MATLAB and crunch it in just that fashion. Cheers! --Dan. ------------------------------ From: mcherriman@xxx.au Date: Wed, 19 Jun 96 09:18:46 Subject: [none] Hello, I am building a simple MAP controlled system for a 2litre turbo. It is micro-controlled and basically fires each injector with the spark signal, and the duration is based linearly on the MAP output. There is also a 3d correction table which gives a correction factor for RPM and MAP (to adjust mixture, and to compensate for changes in volumentric efficiency with rpm & boost). This works quite well, but I dont know what mixtures should be used theoretically at boost. I have assumed a 14:1 mixture at light loads (about 1/2 bar absolute) and 12:1 at 1 bar (absolute). Presumably I should keep enrichening the mixture as boost increases, but what to!!! (I am ignoring volumetric efficiency changes with rpm at the moment) My aim is 1 bar boost pressure, so does anyone know approx. what mixtures you should use at this level with an intercooled motor. It must level off at some point (maybe 8 or 9:1). I have heard that turbo motors like very rich mixtures under boost. Any help appreciated. Mark. ------------------------------ From: Frank F Parker Date: Tue, 18 Jun 1996 22:30:46 -0400 (EDT) Subject: Re: oxygen sensor > ---------- > From: toyota-mods-owner > To: Craig A Terlau > Cc: Daucott; mr2-digest; Toyota-mods > Subject: oxygen sensor > Date: Tuesday, June 18, 1996 3:35PM > > Here's one for the fuel injection experts. I'm presently running in my > fuel injected turboed 18RG (without the turbo till the head gets > retensioned) and i would like to run an O2 sensor, firstly to help tuning > and secondly as a warning of lean outs at high boost. Apparently single > wire sensors only last about a week when using leaded fuel as they get > lead coated at low exhaust temps. Someone suggested that the 3 wire > sensors (which are heated) may last longer. Has anyone tried this or know > if it has been sucessfully used in a leaded fuel car. > > Cheers, > > ~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~ > Justen Simpson simpson@xxx.au > CRC for Freshwater Ecology, Uni of Canberra, Australia > ~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~^~ > Yes, a heated sensor works very well. If you use both a digital vm to read voltage and a fast responding led readout meter so you can see excursions sensor makes, you can tell when sensor is getting poisoned as range of excersions will reduce. Can regenerate sensor for furthur use by running in unleaded car for few weeks. Be aware that special sensors are used for a/f meters for reduced flow and constant 650 deg C temperature. Frank Parker 93 Civic EX vtec custom turbo 89 S-10 L98 V-8 with TFS/DFI/SuperRam > ------------------------------ From: "Lebens, Rick J" Date: Tue, 18 Jun 1996 22:30:32 CST Subject: Re: Home-grown 5th wheel project don't most bicycle speedos work with a reed relay and a magnet?? Will this work turning your bike wheel at 129 mph? ------------------------------ From: pfenske@xxx.ca (peter paul fenske) Date: Wed, 19 Jun 1996 00:36:54 -0700 Subject: Re: AFR control >Munch......... >We need accurate air/fuel ratio (AFR) control over a wide range of >chomp.......... >Hi Eric >I suppose you could do what most of the OEMs do. That is use >corrector tables based on O2 feedback. Use a lookup table >that is close and have the ECM build a modifier table. This is based >on the time the O2 sensor spends above and below the set point. >Most closed loop systems use this approach. >For WOT closed loop around 14.7 is really not a good idea. Even with >EFI fuel distribution is not perfect and I believe best power and torque >are closer to 13 to 1. For this I suggest using the closest load point >modifier from the ECM closed loop table to the current WOT setting >and then enriching that modifier to get the richer mix. Thus closed loop >setting could still correct open loop operation. >I quess there are many ways to do this. Just my 2 sense. > >Is this a workable AFR control procedure? > >Prob works just as well >Eric > > >GL: peter ------------------------------ End of DIY_EFI Digest V1 #171 ***************************** 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".