DIY_EFI Digest Wednesday, 22 July 1998 Volume 03 : Number 345 In this issue: Re: force sensor... RE: More truck stuff Re: force sensor... Re: Thermal Sensor and Load Sensor Re: force sensor... Re: Web site for DIY_EFI Re: projects, when are are they going up? Re: force sensor... trouble codes on a 1995 Eagle Talon 735i DME on BMW 325. Re: Thermal Sensor and Load Sensor Re: force sensor... Re: force sensor... See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Daniel R. Henriksson" Date: Tue, 21 Jul 1998 16:28:12 +0200 (MET DST) Subject: Re: force sensor... I recently acuired a water-brake dynamometer. I'm now looking for some force sensing device, to use as a torque-meter, it should be a robust temp compensated one, drag or pull doesn't matter. It should have a voltage or PWM output. Any ideas? Finally i can make some serius mapping of my home efi... ;-) /Daniel ------------------------------ From: "Reiswig, George" Date: Tue, 21 Jul 1998 08:48:38 -0700 Subject: RE: More truck stuff [George Reiswig] Dan wrote: > Yeah that's kinda what I was trying to say. It does effect the computer > though. These all signal with a 0 - 5 v signal so if the larger MAF > signals > 4 volts say, the computer is calibrated to the stock MAF and is expecting > a certain mass of air but is actually getting something more. So, it runs > leaner in open loop and maybe in closed loop as well (depending on how big > the difference is). > [George Reiswig] This bears out under the experiments I did last night. BTW, Randy, I was right in my logic but wrong in my premise when I talked to you last evening...restricting the flow over the bypass hole (where the hotwires are) makes the engine run leaner. Makes sense, because the ECM thinks that less air is coming in. Duh. For clarity's sake, hereafter when I refer to the "bypass oriface," I'm talking about the little ~8mm hole where the hot wires are. Interestingly, my engine idled very rough with my air cleaner assembly taken off the MAF unit. Put it back on, and the idle smoothed out. The rough idle was also due to a lean condition, judging from the O2 sensor output. Why, I asked, would it run lean without the cleaner assembly on? If you recall, my intake is now positioned almost directly above my headers. If I put anything below the MAF intake (hand, paper, aluminum), anything that would block the convection coming off the headers, the idle and mixture improved. Apparently, the really hot air coming off the headers is fooling the hot wires. An interesting point...one might theorize that, since the air actually going into the engine is the same temp as that being measured, the MAF should compensate for the change in temp/density. But it couldn't, at least at that flow rate. I also tried it at part throttle, with similar results. One wonders what the actual effective temperature range for a hot wire MAF really is. [George Reiswig] (SNIP) > computer uses a voltage passed by the hot wires as its data to determine air > > flow (is that right, it's looking at a voltage, not a resistance?), then > > On mine, it measure voltage. Yours is more than likely the same. > [George Reiswig] So an increase in voltage signals an increase in air flow, or what? > > multiplying that voltage by a factor of two should get you in the > ballpark. > > Nes pas? > > Maybe. That's assuming that the relationship between the mass flowing > through the MAF is linear with the voltage output. It probably is or is > very close to it but I'd want documentation or flow test results to make > sure. [George Reiswig] Actually, all I think I'm assuming here is that the relationship between voltage out and flow rate is one which the computer expects, a safe bet. In other words, suppose that throttle position X gives you flow rate F, and the MAF registers that as voltage +V. If you add a second oriface that also can flow F, then your POTENTIAL (this is the sticking point, I think) flow rate is 2F. The computer, in order to put in the appropriate fuel mixture, should see a voltage of +2V. In actuality under these conditions, the MAF would probably see something less than +V, say +.8V (I'm guessing that opening up the second large oriface will decrease the flow over the wires by less than half...that could be the showstopper. Also, it may be the case that halving the flow over the hot wires will not cut the voltage out in half. But, in theory, you should be able to find the right multiple for the voltage, and the relationship between air flow and voltage would be maintained)(Getting tired of parenthetical statements?). So, you should be able to multiply the measured voltage by (2/.8), or 2.5, and you'll end up with 2V. It could happen! [George Reiswig] (MORE SNIPPAGE) > Cost is minimal (although I do like the idea of a Vortec better). I > already have most of the hardware I need. Total cost including the > injector (maybe 2) and development tools should come in under about > $300. Most of that is the tools. Once I get one working, follow-ons > could be as little as $100 - $150 depending on the injector source (new > or used) and how many I end up using. I'm leaning towards two right > now. Switched alternately to give a steady supply of fuel rather than > pulses and still not exceed the duty cycle of a single injector. > [George Reiswig] This is interesting. What's the breakdown that you have on parts? How much is the turbo, how much is the second MAF, and so forth. Shoot, *I* could almost afford $300! As I mentioned to Randy, I looked under some hoods yesterday. Most vehicles with similar displacement engines have larger MAF openings. Toyotas, for example, look positively massive by comparison. My guess is that there is a ratio of bypass hole size to main oriface size. If the bypass for the hot wires is 5mm in diameter, and the main oriface is 40mm, that's a 1:8 ratio. Again theoretically, if you increased one diameter by 50%, you should be able to do the same to the other diameter and maintain the ratio. However, I don't know exactly what the relationship is of the slot inside the main oriface to the flow over the hot wires. It looks like it's almost a venturi setup, such that flow over the main oriface walls will create a partial vacuum in that slot, sucking air in through the bypass oriface. I don't know whether or not I'd have to also change that slot size correspondingly, but that wouldn't be too hard. In fact, you could make that adjustable, just as you could the bypass oriface. GR ------------------------------ From: rhuish@xxx.com Date: Tue, 21 Jul 1998 09:27:35 -0700 Subject: Re: force sensor... How about a "load cell".....multi positional on an arm / lever for different power levels? Just an idea. > > I recently acuired a water-brake dynamometer. > I'm now looking for some force sensing device, to use as a torque-meter, > it should be a robust temp compensated one, drag or pull doesn't matter. > It should have a voltage or PWM output. > > Any ideas? > > Finally i can make some serius mapping of my home efi... ;-) >From: "Daniel R. Henriksson" Bob Cuda-65 - Angels Camp, Calif. cudabob@xxx.com http://www.goldrush.com/~rhuish/ ------------------------------ From: steve ravet Date: Tue, 21 Jul 1998 11:10:10 +0000 Subject: Re: Thermal Sensor and Load Sensor Mike Fahrion wrote: > > >Mike Fahrion wrote: > >> > >> Some newer GM systems have a parameter called "Gearbox > Torque" > >> and "Delivered Engine Torque" that is supported on some of > the > >> higher end cars. These are (nearly) real time values, does > >> anyone know how they are derived? There are seperate > parameters > >> labeled "Engine Load Value" that is derived from air flow. There was a mention of this some time ago, either here or somewhere else. It had to do with measuring hydraulic pressure somewhere inside the transmission - --steve - -- Steve Ravet International Meta Systems http://www.imes.com steve@xxx.com ------------------------------ From: goflo@xxx.net Date: Tue, 21 Jul 1998 09:19:40 -0700 Subject: Re: force sensor... The water brake setups I'm familiar with have a torque arm take-off designed to push on a hydraulic cylinder - The torque is read off an appropriately calibrated pressure gauge, and HP is calculated from RPM & torque. Many kinds of pressure sensors could be adapted to the task. Piezo transducers come to mind, but I know of no reasonable way to acquire small quantities of them - Perhaps someone on the list does. Failing that my approach would be to use a small hydraulic cylinder to pressurize a gas captured in a tube, and measure the gas pressure with a Motorola MPX5XXX transducer, 0-5 V output, available in various pressure ranges. Presume you wish to interface this output with a computer. If you need more specifics post the details of your dyno & what torque range you are trying to measure - A lot of guys on this list are familiar with this stuff. Regards, Jack Daniel R. Henriksson wrote: > I recently acuired a water-brake dynamometer. > I'm now looking for some force sensing device, to use as a torque-meter, > it should be a robust temp compensated one, drag or pull doesn't matter. > It should have a voltage or PWM output. > Any ideas? > Finally i can make some serius mapping of my home efi... ;-) ------------------------------ From: steve ravet Date: Tue, 21 Jul 1998 11:26:32 +0000 Subject: Re: Web site for DIY_EFI TWong29770@xxx.com wrote: > > can someone tell me what the website address for our list is? > > Thanks in Advance, > > Tom Wong try efi332.eng.ohio-state.edu That's the main page, with a link to the diy-efi page, and a link to the efi332 page. - --steve - -- Steve Ravet International Meta Systems http://www.imes.com steve@xxx.com ------------------------------ From: steve ravet Date: Tue, 21 Jul 1998 11:34:50 +0000 Subject: Re: projects, when are are they going up? Mattz wrote: > > I was wondering when the info for the ION (knock detection) > and EGOR was going to be updated on the web site. > ??? > > z That's still on my todo list. Since Gar took his ball and went home, there probably won't be any new information, but I still want to go through the archives and pull out as much as is in there. When? Soon, hopefully. I don't get as much time as I'd like to work on diy-efi. - --steve - -- Steve Ravet International Meta Systems http://www.imes.com steve@xxx.com ------------------------------ From: goflo@xxx.net Date: Tue, 21 Jul 1998 09:54:34 -0700 Subject: Re: force sensor... The piezo transducers I referred to are called load cells by the trade. There are hundreds of sites devoted to these things, but I have not found a reasonably priced onesy-twosy source. Anybody know? Regards, Jack rhuish@xxx.com wrote: > > How about a "load cell".....multi positional on an arm / lever for different power > levels? Just an idea. > > > > I recently acuired a water-brake dynamometer. > > I'm now looking for some force sensing device, to use as a torque-meter, ------------------------------ From: "Jim Wackermann Jr." Date: Tue, 21 Jul 1998 14:13:43 -0400 Subject: trouble codes on a 1995 Eagle Talon My sister has a Talon ESI with a 2.0 liter engine, 5 spd. The "check engine" light has come on and remains on. I work on my own cars, which are chevys but i am not to familiar with chrysler cars. I ran the code test by turning the key on = off 3 times and i got a 3,3,6,5,5. could someone please help me figure out what these codes mean and give me some insight as to what the problem could be. thank you, Jim bungy@xxx.net ------------------------------ From: "bmw digest" Date: Tue, 21 Jul 1998 11:33:03 PDT Subject: 735i DME on BMW 325. Hi all! I'm about to buy a BMW 325i -93 but it has an broken DME box. The sales gay says that he will replace it with a one from a 735i.Will that fit? Also is it a good thing to buy a car that has had a broken DME? Please respond to this address and also send a copy with less than 130 digits to +46707176352@xxx.se Thanks in advance Magnus J ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com ------------------------------ From: Shannen Durphey Date: Tue, 21 Jul 1998 22:41:31 -0600 Subject: Re: Thermal Sensor and Load Sensor Mike Fahrion wrote: > > >Mike Fahrion wrote: > >> > >> Some newer GM systems have a parameter called "Gearbox > Torque" > >> and "Delivered Engine Torque" that is supported on some of > the > >> higher end cars. These are (nearly) real time values, does > >> anyone know how they are derived? There are seperate > parameters > >> labeled "Engine Load Value" that is derived from air flow. > >> > >> -mike > >> mfahrion@xxx.com > > > >First saw that on 96 pickup w/5.0l Vortech, and automatic > trans. > >I wonder if auto trans is the key there. Also think that fuel > >consumption was displayed, too, which is unusual on gasoline > >engines. > >Shannen > > I am under the impression also that the automatic transmission > plays a part in this. Any ideas how its done? If it is > entirely in the tranny, it is compensated because it reads about > 5 ft-lbs at idle in park. > > -mike > mfahrion@xxx.com No, but I'm kinda curious. Need to get in touch with the guy who teaches trans classes here. He'd be really curious, especially if he could use it in a hot rod. ; ) Shannen ------------------------------ From: bamcknig@xxx.com Date: Tue, 21 Jul 1998 23:31:54 +0000 Subject: Re: force sensor... Daniel I vote for Jack's solution, Hydraulic cylinder to Motorola sensor. I think I have bought them for under 25 in 1s and 2s. Bob McKnight Phx AZ PS I think Newark has them ------------------------------ From: "Andrew W. Macfadyen" Date: Wed, 22 Jul 1998 09:02:11 +0100 Subject: Re: force sensor... The only really viable option is a strain gauges either applied directly to some part of the reaction mountings of the brake or in the form of separate load cell. The simplest application is too mount the strain gauges on the upper and lower surfaces of a beam (bar) in plain bending, as most dyno usually have a reaction bar which was connected to the traditional spring balance this would be the ideal arrangement. Temperature compensation is achieved by mounting 4 strain gauges in a Wheatstone Bridge arrangement, with the gauge in tension in the diagonally position from that in compression, the other 2 gauges are dummies for temperature compensation mounted on an unstressed part of the structure. Add a constant voltage source and an instrumentation grade OP amp such as an AD622N and you have your sensor. I have designed a couple of load cells for industrial robots using wire strain gauges and can assure that these will give highly accurate repeatable results. Daniel R. Henriksson wrote: > I recently acuired a water-brake dynamometer. > I'm now looking for some force sensing device, to use as a torque-meter, > it should be a robust temp compensated one, drag or pull doesn't matter. > It should have a voltage or PWM output. > > Any ideas? > > Finally i can make some serius mapping of my home efi... ;-) > > /Daniel ------------------------------ End of DIY_EFI Digest V3 #345 ***************************** 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".