From owner-diy_efi Thu Sep 1 15:21:09 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA23417; Thu, 1 Sep 94 15:21:09 GMT Received: from psi.com by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA23412; Thu, 1 Sep 94 11:21:05 -0400 Received: from khis.com (charon.khis.com) by psi.com (4.1/2.1-PSI/PSINet) id AA05029; Thu, 1 Sep 94 11:20:56 EDT Received: from alamo by khis.com (4.1/SMI-4.1) id AA01051; Thu, 1 Sep 94 10:24:14 CDT Received: from khan.khis.com by alamo (4.1/SMI-4.1) id AA01425; Thu, 1 Sep 94 10:12:09 CDT From: king@khis.com (Robert King) Message-Id: <9409011512.AA01425@alamo> Subject: Re: Injection of a siamesed(sp?) head To: DIY_EFI Date: Thu, 1 Sep 1994 10:15:54 -0500 (CDT) In-Reply-To: <9408312229.AA09503@mercury.uah.ualberta.ca> from "Andrei Chichak" at Aug 31, 94 04:33:39 pm X-Mailer: ELM [version 2.4 PL23] Content-Type: text Content-Length: 1559 Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI > > Okay here's the problem... a BMC/Leyland/Rover "A" series engine (as used > in an Austin Mini or MG Midget) has a siamesed head. That means that each > pair of cylinders shares a common intake port. In this case a four > cylinder engine has 2 intake ports and 3 exhausts. The BMC "B" series > engine is the same (as used in the MGB). > > Here is the question...with a sequential injection system, should one use > two injectors in each port - one per cylinder - or one injector servicing a > pair of cylinders firing twice the rate? You might have a problem mounting two injectors in one port. From a real estate point of view, one injector doing double duty would be a better solution, but I don't know how the injector would react to the increased load. You may also have troubles wiring the thing, but I expect that could easily be overcome with some simple electronics. +-----------------------------------------------------------------------+ | Robert A. King | | | Systems Software Engineer | | | Kodak Health Imaging Systems | "I drank WHAT?!?" -- Socrates | | | | | king@khan.khis.com | | +-----------------------------------------------------------------------+ | The opinions expressed here arn't even mine, much less my employer's! | +-----------------------------------------------------------------------+ From owner-diy_efi Thu Sep 1 16:04:23 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA24007; Thu, 1 Sep 94 16:04:23 GMT Received: from relay1.UU.NET by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA24002; Thu, 1 Sep 94 12:04:19 -0400 Received: from camelot.dsccc.com by relay1.UU.NET with SMTP id QQxfmm29356; Thu, 1 Sep 1994 12:04:07 -0400 Received: from optilink.dsccc.com by camelot.dsccc.com (5.65c/SMI-V1.8) id AA16879; Thu, 1 Sep 1994 11:07:30 -0500 Received: from montreal by optilink.dsccc.com (4.1/SMI-4.0) id AA19425; Thu, 1 Sep 94 09:03:44 PDT From: marrone@optilink.dsccc.com (Frank Marrone) Message-Id: <9409010858.ZM1446@montreal> Date: Thu, 1 Sep 1994 08:58:48 -0700 In-Reply-To: John S Gwynne "Project update (long)" (Aug 31, 10:30pm) References: <9409010230.AA20841@coulomb.eng.ohio-state.edu> X-Mailer: Z-Mail (3.0.1 23feb94) To: DIY_EFI Subject: Re: Project update (long) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI > - I need a ``smart'' power supply for use in the car..... What is a smart power supply? Inquiring power supply engineers want to know. -- Frank Marrone at marrone@optilink.dsccc.com 1965 Sunbeam Tiger B9471116 From owner-diy_efi Thu Sep 1 18:12:03 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA24609; Thu, 1 Sep 94 18:12:03 GMT Received: from mercury.uah.ualberta.ca by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA24604; Thu, 1 Sep 94 14:12:00 -0400 Received: from [129.128.109.42] by mercury.uah.ualberta.ca (5.4.2/200.1.1.4) id AA11901; Thu, 1 Sep 1994 12:10:05 -0600 Message-Id: <9409011810.AA11901@mercury.uah.ualberta.ca> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Thu, 1 Sep 1994 12:14:11 -0700 To: DIY_EFI From: agc@mercury.uah.ualberta.ca (Andrei Chichak) Subject: Re: Injection of a siamesed(sp?) head Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI At 9:04 AM 9/1/94 +0930, Don Gossink wrote: >After many discussions with people all over the place, the best solution would >involve six injectors. Two Large ones and four smaller ones, this shouldn't >be to bad for a standard cpu to handle seeing most handle up to 8 injectors. > > >Anyway why 6? >Ill attempt to Draw how they should be placed > > > Cylinder Head > >Inlet Manifold \ | / \ | / > *\ /* *\ /* > # # > ># - Large Injectors >* - smaller injectors. ... >Goodluck > >Don Interesting idea, now two supplimentary questions: 1) are there injectors small enough to do this task, the beast I'm looking at is a 60 over 1275 Cooper 'S which weighs in at about 1330CC...aren't 6 injectors going to have a problem OPENING with a pulse that narrow? 2) since the timing is 1342 or equivalently 34-21 the cylinders within the intake ports are 180 degrees apart. How long do injectors have to be quiescent before you can hit them again. In your diagram, or with a total of 2 injectors, you are asking the large injectors to dance to a Reggae beat, will they have a problem closing reliably at higher RPM? Andrei -- Andrei Chichak | Information Systems agc@mercury.uah.ualberta.ca | University of Alberta Hospitals (403) 492 - 4431 (work) | 8440 112 Street Edmonton, Alberta (403) 492 - 3090 (fax) | CANADA T6G 2B7 From owner-diy_efi Fri Sep 2 01:21:51 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA27155; Fri, 2 Sep 94 01:21:51 GMT Received: from audrey.Levels.UniSA.Edu.Au by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA27126; Thu, 1 Sep 94 21:21:42 -0400 Received: from pepe.levels.unisa.edu.au by spri.levels.unisa.edu.au with ESMTP id KAA16238; Fri, 2 Sep 1994 10:51:38 +0930 Received: from localhost by pepe.levels.unisa.edu.au id KAA01033; Fri, 2 Sep 1994 10:49:20 +0930 Date: Fri, 2 Sep 1994 10:49:20 +0930 From: don@spri.levels.unisa.edu.au (Don Gossink) Message-Id: <199409020119.KAA01033@pepe.levels.unisa.edu.au> To: DIY_EFI Subject: Re: Injection of a siamesed(sp?) head Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI > Blah > Blah >Interesting idea, now two supplimentary questions: >1) are there injectors small enough to do this task, the beast I'm looking >at is a 60 over 1275 Cooper 'S which weighs in at about 1330CC...aren't 6 >injectors going to have a problem OPENING with a pulse that narrow? Yes, there are a variety of injectors available, lets see Ducatti use multipoint injection on their 750cc bikes. Suzuki, use multipoint injection on the swift (1000cc - 1300cc car). Just as apoint of interest my little fire breather being built is a balanced and blueprinted 1310cc (Cooper 'S' motor) withg lots of nice little goodies in it. >2) since the timing is 1342 or equivalently 34-21 the cylinders within the >intake ports are 180 degrees apart. How long do injectors have to be >quiescent before you can hit them again. In your diagram, or with a total >of 2 injectors, you are asking the large injectors to dance to a Reggae >beat, will they have a problem closing reliably at higher RPM? Of course injectors should be able to cope with this sort of treatment, I mean to say the Rover offering has to open and close 4 times as often as a multipoint version and apparently it is very reliable above 7000rpm. The question is how hard are you going to turn your engine over. I'm aiming for an upper bound of 8000rpm myself. A word of caution though you get what you pay for. I think the harder problem is supplying the fuel pressure for the fuel rail. Where to put the extra fuel pump? It must be near the engine but where? Don >Andrei From owner-diy_efi Fri Sep 2 03:44:54 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA27946; Fri, 2 Sep 94 03:44:54 GMT Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA27941; Thu, 1 Sep 94 23:44:52 -0400 Date: Thu, 1 Sep 94 23:44:52 -0400 From: jsg (John S Gwynne) Message-Id: <9409020344.AA27941@coulomb.eng.ohio-state.edu> To: DIY_EFI Cc: jsg Subject: Re: Project update (long) In-Reply-To: Your message of "Thu, 01 Sep 94 08:58:48 PDT." <9409010858.ZM1446@montreal> Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI -------- -------- In message <9409010858.ZM1446@montreal> , you write: | | | > - I need a ``smart'' power supply for use in the car..... | | What is a smart power supply? Inquiring power supply engineers want to know. Did I hear VOLUNTEER ????? Smart huh.... how about a "real" supply. I'm not prepared to make specifications yet, but... here's what I had in mind. - +5VDC +/-5% at 2A max continuous (0mA min) - +/-15VDC +/- 10% at 0.5A - input 8-16VDC w/the spikes and dropouts associated with the starter running. - industrial temperature range (no internal ventilation; i.e., no external air vented into the case) - short circuit protected - power on diagnostics that will not turn-on the outputs unless voltages are within tolerance. (what can we do to prevent damage to the rest of the circuit in the event of a supply failure?) - notify cpu of "power off" condition (see next item). - supply power for say 0.1 sec after input power is removed. - shutdown command from cpu. - LED indicators for +5VDC, +15VDC, -15VDC, and input power. - power-on lamp test function for the above. - external voltage (load voltage) sensing - must be able to reverse the polarity of the input supply without damage. - turn-on to output voltages within tolerance delay of less than 0.3 sec. Comments? I'm not real concern with efficiency (the car has a 140A alt. :) ) or the technology used... I just want it to work and last... I'm tired of buying after-market crap that doesn't work... John S Gwynne Gwynne.1@osu.edu _______________________________________________________________________________ T h e O h i o - S t a t e U n i v e r s i t y ElectroScience Laboratory, 1320 Kinnear Road, Columbus, Ohio 43212, USA Telephone: (614) 292-7981 * Fax: (614) 292-7292 ------------------------------------------------------------------------------- From owner-diy_efi Fri Sep 2 06:29:18 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA28257; Fri, 2 Sep 94 06:29:18 GMT Received: from kcbbs.gen.nz by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA28252; Fri, 2 Sep 94 02:29:10 -0400 Received: from localhost (steveb@localhost) by kcbbs.gen.nz (8.5/8.5) id SAA22871; Fri, 2 Sep 1994 18:28:58 +1200 From: Steve Baldwin Message-Id: <199409020628.SAA22871@kcbbs.gen.nz> Subject: Something a little different To: DIY_EFI Date: Fri, 2 Sep 1994 18:28:57 +1200 (NZST) In-Reply-To: <9408312135.AA09944@alamo> from "Robert King" at Aug 31, 94 04:39:43 pm X-Mailer: ELM [version 2.4 PL21] Content-Type: text Content-Length: 1111 Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI In the interest of getting the traffic moving again, maybe somebody has some ideas for me to pursue. The motor I want to play with is a flathead for which I have a blower. This motor is most likely to see service in a deuce coupe so looks count as much as the other benefits of re-inventing the wheel. Since the motor is blown, I have to run the fuel through from the top rather than port injecting to keep the blower cool. Port injection on the flathead would require the injectors in the valley to get the charge to hit the valve head anyway. I'm not too keen on that. So since the mixture is going to get all munched up in the blower, there is little advantage in individually controlled injectors. What I am thinking of is similar to the Hilborn type of setup but with a bit more control than used with the standard pill arrangement. Sort of progressive use of injectors combined with PWM to the distribution block. I really haven't thought this part out too far yet, so I'm open to any suggestions or comments. What sort of pressure ranges do the injector nozzles used in nitrous systems use ? Steve. From owner-diy_efi Fri Sep 2 15:24:28 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA00375; Fri, 2 Sep 94 15:24:28 GMT Received: from tomcat.al.noaa.gov by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA00370; Fri, 2 Sep 94 11:24:25 -0400 Received: from aztec.al.noaa.gov by tomcat.al.noaa.gov with SMTP id AA10609 (5.65c/IDA-1.4.4 for ); Fri, 2 Sep 1994 09:30:11 -0600 Message-Id: <199409021530.AA10609@tomcat.al.noaa.gov> Date: 2 Sep 1994 09:22:51 U From: "Ciciora Steve" Subject: FW: Re: Project update (long) To: DIY_EFI Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI In message <9409010858.ZM1446@montreal> , you write: I'm not prepared to make specifications yet, but... here's what I had in mind. - +5VDC +/-5% at 2A max continuous (0mA min) - +/-15VDC +/- 10% at 0.5A - input 8-16VDC w/the spikes and dropouts associated with the starter running. - industrial temperature range (no internal ventilation; i.e., no external air vented into the case) - short circuit protected - power on diagnostics that will not turn-on the outputs unless voltages are within tolerance. (what can we do to prevent damage to the rest of the circuit in the event of a supply failure?) - notify cpu of "power off" condition (see next item). - supply power for say 0.1 sec after input power is removed. - shutdown command from cpu. - LED indicators for +5VDC, +15VDC, -15VDC, and input power. - power-on lamp test function for the above. - external voltage (load voltage) sensing - must be able to reverse the polarity of the input supply without damage. - turn-on to output voltages within tolerance delay of less than 0.3 sec. Wow, I'm not sure I want to see the specs when you _do_ have a chance to think about it! After you build yourself one, can you build me one? :-) What I'm doing for now is to take a 12V DC to 120V AC inverter and run some lambda switching power supplies off of it. I even run my old 8Mhz '286 off of it (don't have a laptop... yet). I found a bunch of surplus compaqu 12V DC EGA monochrome monitors for $5. Anyway, I'm getting carried away. Do you really need to have it supply power for about 0.1 sec? I was planing on having the computer powered all the time, and can enter a low-current shutdown mode. Or at least the power supply always on. Or wait, how about this: The ignition switch turns on the power supply, and when the key turns the car off, the computer does it's shut down routines, and then the computer shuts off the power supply. Guss What! I'm getting a REAL C compiler for the 6811! In exchange, I have to write a few simple programs for the group next door... While I know other CPUs would be better suited for this project, I'm now very committed to the 6811. -Steven Ciciora From owner-diy_efi Tue Sep 6 15:44:33 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA02834; Tue, 6 Sep 94 15:44:33 GMT Received: from smtp.utexas.edu by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA02829; Tue, 6 Sep 94 11:44:30 -0400 Received: from mail.utexas.edu (mail.utexas.edu [128.83.126.1]) by smtp.utexas.edu (8.6.7/8.6.6) with ESMTP id KAA21977 for ; Tue, 6 Sep 1994 10:44:01 -0500 From: BigBrother@mail.utexas.edu Received: from [128.83.128.88] (slip-10-8.ots.utexas.edu [128.83.128.88]) by mail.utexas.edu (8.6.7/8.6.6) with SMTP id KAA20515 for ; Tue, 6 Sep 1994 10:43:55 -0500 Message-Id: <199409061543.KAA20515@mail.utexas.edu> X-Sender: BigBrother@mail.utexas.edu (Unverified) Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Date: Tue, 6 Sep 1994 10:43:40 -0600 To: DIY_EFI Subject: Frequency to Voltage Conversion: how? Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI MAP and BP sensors apparently do not return voltage as output. Instead the oscillate at a frequency which corresponds to the absolute pressure. What electronics are involved with frequency to voltage conversion? This brings up another point: what output frequency corresponds to what pressure level? I'm sure we could test one to find out, but isn't there already some book or manual that gives in depth data on sensor readings? If we have to test every sensor, it is going to take a LONG time. Surely Ford, Chevy, and/or Bosch, publishes a manual for servicing EFI that describes how each particular type of sensor responds. From owner-diy_efi Tue Sep 6 15:55:45 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA02867; Tue, 6 Sep 94 15:55:45 GMT Received: from abacus.gsfc.nasa.gov by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA02862; Tue, 6 Sep 94 11:55:43 -0400 Date: Tue, 6 Sep 1994 12:00:59 -0400 (EDT) From: Dirk Broer To: DIY_EFI Message-Id: <940906120059.18c1@abacus.gsfc.nasa.gov> Subject: Re: frequency to voltage conversion. Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI >MAP and BP sensors apparently do not return voltage as output. Instead >the oscillate at a frequency which corresponds to the absolute pressure. >What electronics are involved with frequency to voltage conversion? Your best bet for accuracy is a frequency counter - this would also tend to eliminate noise (a digital filter if you will). Suppose you find out the MAP sensor outputs between 50-150 HZ depending on pressure. Hook up an 8-bit counter and read it every 10Hz. You'll expect readings between 5-15 counts - this is a little low on accuracy but allows for rapidly changing pressure levels. On the flip side, if you read once a second you may end up with 50 to 150 counts but a rapid change would not be noticed - or rather it would be averaged in. Every time you latch the current count you clear the counter. Dirk From owner-diy_efi Tue Sep 6 16:04:39 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA02933; Tue, 6 Sep 94 16:04:39 GMT Received: from tomcat.al.noaa.gov by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA02928; Tue, 6 Sep 94 12:04:33 -0400 Received: from aztec.al.noaa.gov by tomcat.al.noaa.gov with SMTP id AA16676 (5.65c/IDA-1.4.4 for ); Tue, 6 Sep 1994 10:10:30 -0600 Message-Id: <199409061610.AA16676@tomcat.al.noaa.gov> Date: 6 Sep 1994 10:01:54 U From: "Ciciora Steve" Subject: FW: Frequency to Voltage Conversion: how? To: DIY_EFI Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI Someone writes: MAP and BP sensors apparently do not return voltage as output. Instead the oscillate at a frequency which corresponds to the absolute pressure. What electronics are involved with frequency to voltage conversion? This brings up another point: what output frequency corresponds to what pressure level? I'm sure we could test one to find out, but isn't there already some book or manual that gives in depth data on sensor readings? If we have to test every sensor, it is going to take a LONG time. Surely Ford, Chevy, and/or Bosch, publishes a manual for servicing EFI that describes how each particular type of sensor responds. Most single chip computers can measure frequency much better than voltage, which is why MAF sensors output frequency. Since I don't know the frequency range for this sensor, I can't comment on the best circut to do a freq. to voltage conversion. My GM map sensor outputs a voltage proportional to the pressure *and reference voltage*. I did a pressure calibration and found it to be extreemly linear and very dependent on ref. voltage. Three terminals: ground, ref in, and output voltage. I gave mine 5.0 volts. I don't have the data handy, but can post if you would wish. I plan on calibrating all that I own to find out repeatability info. The MAP sensor I use is used in my '89 Berettas (4 and 6 cyl), my sister's '89 Corsica, and my friend's Jeep. - Steven ciciora From owner-diy_efi Tue Sep 6 18:20:36 1994 Received: by coulomb.eng.ohio-state.edu (920330.SGI/920502.SGI) id AA03377; Tue, 6 Sep 94 18:20:36 GMT Received: from rain.org by coulomb.eng.ohio-state.edu via SMTP (920330.SGI/920502.SGI) for /usr/local/mail/majordomo-1.92/wrapper resend -p bulk -M 10000 -l Diy_Efi -f Diy_Efi-Owner -h coulomb.eng.ohio-state.edu -s -r DIY_EFI diy_efi-outgoing id AA03372; Tue, 6 Sep 94 14:20:26 -0400 Received: from diginst.UUCP by rain.org with UUCP (4.1/25-eef) id AA29569; Tue, 6 Sep 94 11:17:20 PDT Received: by di.com (UUPC/extended 1.11z); Tue, 06 Sep 1994 10:55:42 PDT Date: Tue, 06 Sep 1994 10:55:42 PDT From: "Dan Bocek" Message-Id: <2e6cad1e.diginst@di.com> Organization: Digital Instruments, Santa Barbara, CA To: "diy_efi"DIY_EFI Subject: Re: Frequency to Voltage Conversion: how? Sender: owner-diy_efi Precedence: bulk Reply-To: DIY_EFI > MAP and BP sensors apparently do not return voltage as output. Instead > the oscillate at a frequency which corresponds to the absolute pressure. > What electronics are involved with frequency to voltage conversion? While it is true that some airflow measuring techniques have a frequency output (the Karmen-vortex sensor, as used on a lot of Mitsubishi cars, comes to mind, although its output is pulse width modulated, so all you have to do is low pass filter the output to get DC) I've never heard of a MAP sensor outputting AC. Where did you get this info? -- Dan Bocek dan@di.com