DIY_EFI Digest Thursday, 27 June 1996 Volume 01 : Number 181 In this issue: Re: Re: DIY_EFI Digest V1 #180 RE: Bosch Motronic AFM => Point - Counterpoint RE: Bosch Motronic AFM => Point - Counterpoint Re: RE: Bosch Motronic AFM => Point - Counterpoint Re: DIY_EFI Digest V1 #180 AC Delco ECM GM Coolant Temp Sensor RE: Bosch Motronic AFM => Point - Counterpoint Re: DIY_EFI Digest V1 #180 Re: Darwin Awards Re: AC Delco ECM A.C. Delco Ecm Re[2]: Re: AC Delco ECM RE: Bosch Motronic AFM => Point - Counterpoint RE: Bosch Motronic AFM => Point - Counterpoint someone tried to reach me? GM Mass Airflow Sensor Re: AC Delco ECM Re: Bosch Motronic AFM => Point - Counterpoint Re: GM Mass Airflow Sensor Missing teeth Re: AC Delco ECM See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: walter.kaufmann@xxx.ch (Walter Kaufmann) Date: Wed, 26 Jun 1996 11:35:03 +0200 Subject: Re: > Wow, the car will have more processing power than engine power (only > kidding). If there is no space why not consider a MAP based system ? Can you get my more information about a MAP based system? (I have look at it. Differential pressure measurment over the butterfly and temparatur compensation and maybe huminity correction and so on...) Is there a manufacturer for this device (body and butterfly)? Thanks Walter P.S. Processing power is cheaper than engine power.... ------------------------------ From: talltom Date: Wed, 26 Jun 1996 04:08:52 -0700 Subject: Re: DIY_EFI Digest V1 #180 My bet would be it would be far easier to fix the system on the BMW. My 81 bmw 745i I believe is analog, l system, has approx 185 rear wheel horsepower(chassis dyno) and gets 18mpg+.(unless I mash it, which I can't do for long) > Re: 280ZX ECU in '78 BMW > Re: Looking for Cadillac Error Codes > Re: OEM CONTROLLERS Intel 8051? > [none] > Re: > So, I need to do something. My options are to try to monkey with the > L-Jet that is in there and see if I can improve things, trial and > error, or to start over and replace the entire ECU and harness. > Nobody says I have to run this thing in a closed loop if I put the > Nissan ECU in there. My bet is that the ECU from the 280ZX is tuned > to run the car maybe a hair rich based upon the input from the AFM, > TPS and O2 sennsor. So, seems like if I tune the AFM and perhaps the > fuel pressure with the Nissan computer then I should be in good > shape, eh? Maybe just an adjustable pressure regulator is what I > need. This must be better to make broad-band changes in the fuel > curve than AFM mucking. > > Later- > _____________________________________________________________________________ > Josh Karnes joshk@xxx.com ------------------------------ From: Brad Anesi Date: Wed, 26 Jun 1996 07:01:58 -0600 Subject: RE: Bosch Motronic AFM => Point - Counterpoint At the risk of continuing this discussion into the new millennium, I present this response from Pat Braden, author of the book "The Alfa Romeo Owners' Bible", in response to our recent discussion. ************************* Forwarded Text ****************************** "2-3 notches on the spring will change the Air Fuel ratio by about 2%" Hate to disagree. Presuming that the spring has any effect on air/fuel ratio, loosening it (that is, allowing more air to enter) would _lean_ the mixture, not richen it. Conceivably, weakening the spring could allow the flapper valve to swing further for a given air velocity, indicating a higher volume of air, for which the control module would immediately provide a richer mixture. However, the mixture would immediately be corrected to the stoichiometric value of about 13.4:1 by the control module, acting on information from the Oxygen sensor. My understanding of the system is that the spring is there only to return the flapper and act as a damper on its actions. Weakening the spring reduces the damping effect, allowing a faster throttle response but not changing the A/F ratio. With any Motronic system, presuming it is in working order, nothing you do to the mixture will change the actual air/fuel ratio because the Oxygen sensor signal will simply force the control module to correct the mixture strength to stoichiometery. With the Oxygen sensor disabled, the easiest way to get a richer mixture is to fool the coolant temperature sensor by putting resistance in line. ------------------------------ From: Mark Reichert Date: Wed, 26 Jun 1996 11:26:15 -0400 Subject: RE: Bosch Motronic AFM => Point - Counterpoint > With any Motronic system, presuming it is in working order, nothing you > do to the mixture will change the actual air/fuel ratio because the Oxygen > sensor signal will simply force the control module to correct the mixture > strength to stoichiometery. Then why even bother to measure it? Mark Reichert markr@xxx.com ------------------------------ From: Land Shark Date: Wed, 26 Jun 1996 09:29:40 -0600 Subject: Re: At 04:02 PM 6/26/96, you wrote: >What system would you recommend for air flow(or air mass flow) measurment? >I know three systems: This one with the round plate in the air flow, the system >with the air 'trap' and that one with the platinium wire(air mass). None of the above :) I would recommend a Bosch hot film mass air sensor ... I know there is one for small engines .. 1.9l and smaller ... Used on the BMW 318i and Z3 for starters... Jim ------------------------------ From: Land Shark Date: Wed, 26 Jun 1996 09:43:09 -0600 Subject: RE: Bosch Motronic AFM => Point - Counterpoint At 07:01 AM 6/26/96 -0600, you wrote: >At the risk of continuing this discussion into the new millennium, I present >this response from Pat Braden, author of the book "The Alfa Romeo >Owners' Bible", in response to our recent discussion. With all due respect to Mr. Braden he has not a CLUE how Motronic works!! >Hate to disagree. Presuming that the spring has any effect on air/fuel >ratio, loosening it (that is, allowing more air to enter) would _lean_ the >mixture, not richen it. Conceivably, weakening the spring could allow the >flapper valve to swing further for a given air velocity, indicating a >higher volume of air, for which the control module would immediately >provide a richer mixture. However, the mixture would immediately be >corrected to the stoichiometric value of about 13.4:1 by the control >module, acting on information from the Oxygen sensor. Really?? Well, #1, stoich. for GASOLINE is arounf 14.68:1 (14.7:1 is the common number) Second, in for example .. a porsche 911 :), the oxygen sensor is only active in the area necessary to pass the emissions test (FTP - Federal Test Procedure) This is done with a WINDOW of speed and load .. any speed (rpm) value greater than X .. or any load (Tl) value greater than Y for Z seconds will cause the system to run open loop .. as does .. 1) WOT 2) Accel 3) Decel fuel cut off 4) Warmup cycle So in ALL these cases the EGO feedback is OFF, and the car acts as if it had none, with the EGO correction in the DME defaulting to 0x8000 which is "one" Now on to the effect of messing with the spring .. if you loosen the spring you will INDEED richen the mixture .. the problem is that while the output function of the meter is a simple Log (base E) function of the air flow, that function is comprised of the COMPLEX functions of the individual components in the DME ... Which are: 1) The flap 2) The spring 3) The cailbrated pot trace Loosening the spring DOES richen things up ALL over the scale, but also CHANGES the function of the curve.. i.e. it's SHAPE ... Since the average joe cannot then tweak the internal Motronic tables to correct this, you start to generate a FALSE load signal in the DME.. This is not good, because the relationship of the whole thing is mathematical and now you have broken it! Those relationships (for a flapper) are .. Q=f(Uv/Up) (fcn is a log function scaled by 2 constants) Tl=Q/(n*Ki) Tl or LOAD is the base for the injection time .. Thou shouldst not mess with T sub ell ... :) >My understanding of the system is that the spring is there only to return >the flapper and act as a damper on its actions. Weakening the spring >reduces the damping effect, allowing a faster throttle response but not >changing the A/F ratio. No, loosening the spring richens the mixture, on accell we add even MORE fuel and get better transitions .. we can do the SAME thing by bumping up the main (non idle, non WOT) fuel table a bit (usually 3-7%).. During EGO, there is no extra emissions, but upon accel, you get more fuel for better transitions .. >With any Motronic system, presuming it is in working order, nothing you >do to the mixture will change the actual air/fuel ratio because the Oxygen >sensor signal will simply force the control module to correct the mixture >strength to stoichiometery. I wont even start talking about skewing the AFR from Lambda=1 by modifying the constants in the EGO feedpack PID control loop .. you can make a normal EGO sensor control things either a bit lean or rich of center this way! >With the Oxygen sensor disabled, the easiest >way to get a richer mixture is to fool the coolant temperature sensor by >putting resistance in line. Actually on most DME's the EASIEST way is to simply adjust the FQS which is on most DME's from 88 and earlier years .. and 8 position (3 bit binary) encoder which changes fueling and spark base parameters .. Jim PS: Sorry to pontificate, but I've just had to UNDO too many messes that were prompted by "experts" ... most people have no IDEA how Motronic DME works They try to make it complicated when in fact it is a SIMPLE deal .. I can always show you commented source code if you are from Missouri ;) ------------------------------ From: WERNER_HAUSSMANN@xxx.com Date: Wed, 26 Jun 96 10:14:08 -0600 Subject: Re: DIY_EFI Digest V1 #180 Yes, I second that. You really don't know what to expect by mixing the Bosch Air Meter with the Nissan ECU. Better to 'fix' what you have, or if it is not broken, then I am sure you can modify it to have it operate better. First thing to do is to measure the AF mixture with the air pump disconnected. If it is too rich you will know you can make it better. Werner ______________________________ Reply Separator _________________________________ Subject: Re: DIY_EFI Digest V1 #180 Author: Non-HP-owner-diy-efi (owner-diy_efi@xxx.edu) at HP-ColSprings,mimegw2 Date: 6/26/96 6:08 AM My bet would be it would be far easier to fix the system on the BMW. My 81 bmw 745i I believe is analog, l system, has approx 185 rear wheel horsepower(chassis dyno) and gets 18mpg+.(unless I mash it, which I can't do for long) > Re: 280ZX ECU in '78 BMW > Re: Looking for Cadillac Error Codes > Re: OEM CONTROLLERS Intel 8051? > [none] > Re: > So, I need to do something. My options are to try to monkey with the > L-Jet that is in there and see if I can improve things, trial and > error, or to start over and replace the entire ECU and harness. > Nobody says I have to run this thing in a closed loop if I put the > Nissan ECU in there. My bet is that the ECU from the 280ZX is tuned > to run the car maybe a hair rich based upon the input from the AFM, > TPS and O2 sennsor. So, seems like if I tune the AFM and perhaps the > fuel pressure with the Nissan computer then I should be in good > shape, eh? Maybe just an adjustable pressure regulator is what I > need. This must be better to make broad-band changes in the fuel > curve than AFM mucking. > > Later- > _____________________________________________________________________________ > Josh Karnes joshk@xxx.com ------------------------------ From: pfenske@xxx.ca (peter paul fenske) Date: Wed, 26 Jun 1996 08:52:02 -0700 Subject: AC Delco ECM Hello Gang Just some more info on GM ECM. FYI the more desirable ECMs are those used in port operation from about 1986 to 1992. The last #s are 165 and 730 on the PN. These two ECMs can use a 16K and a 32K respectably. On the weekend picked up two 165s, one complete tpi harness, and a firebird aircleaner assembly for 50$ can. 730s a bit harder to find though. There are usually several K of unused prom space, as well as several unused inputs and outputs. GM sensors and actuators are just as cheap. About the only hindrance so far is untangling the IO. So if anybody has any info or clues please let me know If someone would like to run a BMW or whatever with one of these let me know. There are virually hundreds of calibrations for these ECMs. Anything from 5.7L to 2.0L. What I have managed to untangle so far are Spark Control, Idle control, Fan control, Speed limiter function. Untested as yet are checksum control and some fueling. If anyone has info to correlate please let me know. With the price and availability these ECMS would be the answer for many EFIers. Also the electronics is far superior to what can be made and believe me I have access to good PCB manufacturing. WEll GL all: peter pfenske@xxx.ca ------------------------------ From: pfenske@xxx.ca (peter paul fenske) Date: Wed, 26 Jun 1996 08:59:11 -0700 Subject: GM Coolant Temp Sensor Hi All FYI The 730 ECM GM uses and others use two pullup resistors in their scheme to linearize their tempeture sensor. This sensor turns out to be a thermistor with a neg temp coef. When cold up to about 122 degrees a 348 and 3.65K resistor are used. This matches to sensor linearity from about 80 to 122 degrees with an error of about 1%. When the ECM senses 122 degrees from the A-D the 348 ohm resistor is switched in. There is less than 1% deviation from straight line between 122 and 250 degrees. True a bit of code with breaks and a shift right(/2) must be used but for most a correction table is necessary only below70 degrees. This results in hex values 0-255 representing temp in celsius. Well Tnx all: peter ------------------------------ From: WERNER_HAUSSMANN@xxx.com Date: Wed, 26 Jun 1996 12:57:43 -0400 Subject: RE: Bosch Motronic AFM => Point - Counterpoint I think both views are correct in the point counterpoint. Most EFI systems do NOT run at closed loop (Stoichiometric) unde r heavy load or WOT. At this time loosening the Air Meter will richen t he mixture. Some older EFI systems and many DIY systems do not run closed lo op at all, and for these the 'spring' allows for fine tuning the AF ratio. There are other ways and this is one that works. For the Bosch systems with the air meter, when changing the trot tle, the air meter will overshoot, the ECU will sense the rate of change and and provide an accelerator pump action. 'Loosening the spring' will increase that accelerator pump action. That is kind of the intend of the discussion. Using the coolent sensor is not as good because the cooling temp erature is not stable. Using the air temperature sensor in the Air meter i s another way to make small adjustments. Werner ______________________________ Reply Separator _________________ ________________ Subject: RE: Bosch Motronic AFM => Point - Counterpoint Author: Non-HP-owner-diy-efi (owner-diy_efi@xxx.ohio-st ate.edu) at HP-ColSprings,uugw2 Date: 6/26/96 8:01 AM At the risk of continuing this discussion into the new millenniu m, I present this response from Pat Braden, author of the book "The Alfa Rome o Owners' Bible", in response to our recent discussion. ************************* Forwarded Text ********************* ********* "2-3 notches on the spring will change the Air Fuel ratio by abo ut 2%" Hate to disagree. Presuming that the spring has any effect on ai r/fuel ratio, loosening it (that is, allowing more air to enter) would _lean_ the mixture, not richen it. Conceivably, weakening the spring could allow the flapper valve to swing further for a given air velocity, indicat ing a higher volume of air, for which the control module would immedia tely provide a richer mixture. However, the mixture would immediately be corrected to the stoichiometric value of about 13.4:1 by the con trol module, acting on information from the Oxygen sensor. My understanding of the system is that the spring is there only to return the flapper and act as a damper on its actions. Weakening the sp ring reduces the damping effect, allowing a faster throttle response but not changing the A/F ratio. With any Motronic system, presuming it is in working order, noth ing you do to the mixture will change the actual air/fuel ratio because the Oxygen sensor signal will simply force the control module to correct th e mixture strength to stoichiometery. With the Oxygen sensor disabled, the easiest way to get a richer mixture is to fool the coolant temperature s ensor by putting resistance in line. ------------------------------ From: WERNER_HAUSSMANN@xxx.com Date: Wed, 26 Jun 96 13:05:07 -0600 Subject: Re: DIY_EFI Digest V1 #180 Hi Josh I don't know as much as Jim. (He let the 'Alfa' guy have it, and rightly so.). But then Jim seems to like the digital ECU better. I don't have access to the Motronic units in the junk yard. 1. You can't get a good idea what the mixture is doing with an O2 sensor. The O2 sensor is only useful to tell you if the mixture is rich or lean, not how much. Try to find someone with a CO meter. or emission meter. Using a dynamometer, accelerometers, or time trials is too hard. You need a way to measure the AFR in the garage so you can see what happens when you change something. A CO meter is the easiest. I have never been able to make a O2 sensor do that. Besides I don't think you have a place for an O2 sensor. 2. If you change the spring slightly, or the fuel pressure slightly, at one point (say no load, 3000rpm) the rest will stay close to calibration. Jim is right, changing the spring position screws up the calibration, especially if you change it a lot. The idea is to calibrate it at cruising and at WOT. You should have a trottle switch that closes at WOT. You set it up for say 13:1 at cruising, and 12:1 at WOT or whatever you think makes sense. 3. Start by measuring the AFR at 3000rpm.Check it at part open trottle, and check it again shorting the two wires that go to the ennrichment. They are shorted for WOT (wide open trottle, check the box on the trottle body, two of the three wires). When shorting the enrichment you should see the AFR get richer. (also a good way to test the CO meter). Depending on the type of ECU you might be able to do the tuning in the ECU. I am only familiar with the Bosch ECU that uses the O2 sensor. (I don't use that feature) also check out http://proffa.cc.tut.fi/~k124775/Injection.html The above is a first step no matter what you plan to do. You first have to be able to measure AFR or any changes you make. Best regards Werner ______________________________ Reply Separator _________________________________ Subject: Re: DIY_EFI Digest V1 #180 Author: Non-HP-joshk (joshk@xxx.com) at HP-ColSprings,shargw2 Date: 6/26/96 8:24 AM OK, I hear that you are the guy who knows how to modify the analog ECU to make the car run leaner (whatever). I can plug in an O2 sensor and measure the mixture without the air pump, no sweat. I can also tighten the spring in the AFM or add a resistor (whatever) to make the car run leaner in range of operation where the AFM is in the game (warmed-up, above idle, below 3000 rpms or so, right?). So then how do I recalibrate the whole system to make it run leaner (and the right amount leaner) at idle, 3000 rpm+, cold-start, etc ? Thanks for your advice. _____________________________________________________________________________ Josh Karnes joshk@xxx.com Renaissance Man http://www.tanisys.com/~joshk/home.htm Tanisys Technology http://www.tanisys.com Austin, Texas '78 BMW 530i | '72 Datsun 240Z | IZCC #308 _____________________________________________________________________________ *** opinions expressed herein are MINE, ALL MINE!! *** ------------------------------ From: brewer@xxx.com (John Brewer) Date: Wed, 26 Jun 1996 14:10:24 -0500 Subject: Re: Darwin Awards Alas, I called the Arizona Highway Patrol. :( I told them I had a fantastic story that I wanted to check out and before I told him what it was, he guessed it was the JATO story. It is in fact an Urban Legend but it is a heck of a good one! John Brewer ______________________________________________________________________ | Huntsville, Alabama, USA. Birthplace of the Saturn V Rocket | | and home of NASA George C, Marshall Space Flight Center, | | U.S. Army Missile Command, U.S. Strategic Defence Command, | |___________High-Tech Industry Center of the SouthEast.______________| "Any man who would trade liberty for security deserves neither." - Ben Franklin ------------------------------ From: Martin Scarr Date: Wed, 26 Jun 1996 13:26:33 -0700 (PDT) Subject: Re: AC Delco ECM Peter- Wish I had some info to contribute for you, but I'm a real newbie when it comes to ECM's. I did want to tell you I think it's great that you're sharing all you're learning about these. I hope to adapt a MAF based system to my '65 turbo Corvair, so I can do away with the old sidedraft Carter. I have a complete EFI setup from a 2.8 V-6 out of a '85 Firebird. I plan on using a Hobbs switch to enrich the mixture under boost. I have good fabricating skills and a shop to make the manifold adapters as needed. How is the code physically extracted from the ECM? I mean where do you attach, at the ribbon cable going to the sub board? Where do you get disassembler software to look at the code? Thanks for all your help Martin Scarr ------------------------------ From: pfenske@xxx.ca (peter paul fenske) Date: Wed, 26 Jun 1996 15:45:56 -0700 Subject: A.C. Delco Ecm >Chompee........ >I did want to tell you I think it's great that you're sharing all you're >learning about these. I hope to adapt a MAF based system to my '65 turbo >Corvair, so I can do away with the old sidedraft Carter. > >I have a complete EFI setup from a 2.8 V-6 out of a '85 Firebird. I > >Muncheee... >Yikes well for 85 and only 85 you are one of the C3 crowd.(ECM 870) >The same ECM resides in my vette and 5.0 camaro with port. I assume you >are not talking throttle body. Prob better off playing with 730 >P4 ecm although what you got is! Well you can fab port injection >and use 5.7 injectors. Sorta depends what boost level. For about >160 Hp stock injectors fine. Over 200 MAF prob runs out of range. >Haven't got calibrations for MAFs. Maybe someone else has >Depends what you are doing. For a mildly spruced corvair six works >fine. Need a magnetic pick to use HEI module and a oxygen sensor >installed. > >How is the code physically extracted from the ECM? I mean where do you >attach, at the ribbon cable going to the sub board? Where do you get >disassembler software to look at the code? > >Some code and lookups reside in a plugin chip in the C3. Unfortunately >some code resides in the MPU. You will need to write a routine in the >plugin rom to offload the MPU rom. If anyone can do this please. > >There are both a 6801 and HC11 dissembler kicking around. >Email me for details. Or look at mot web site. > >Thanks for all your help > >Martin Scarr > >Now if we could only get some help: peter ------------------------------ From: dzorde@xxx.au Date: Thu, 27 Jun 96 08:28:54 Subject: Re[2]: A lot (if not most) aftermarket systems are MAP based because its easier to deal with. A MAP sensor, a water temp sensor, an air temp sensor, a tacho signal and a TPS sensor, and you are off and running. There was a discussion a while back about aftermarket systems, and someone compiled a table of the various systems and their features. Could who ever did this, mabye post it again ? Can you get my more information about a MAP based system? (I have look at it. Differential pressure measurment over the butterfly and temparatur compensation and maybe huminity correction and so on...) Is there a manufacturer for this device (body and butterfly)? Thanks Walter P.S. Processing power is cheaper than engine power.... ------------------------------ From: FIScot@xxx.com Date: Wed, 26 Jun 1996 22:56:51 -0400 Subject: Re: AC Delco ECM In a message dated 96-06-26 17:09:37 EDT, Martin Scarr wrote: > have a complete EFI setup from a 2.8 V-6 out of a '85 Firebird. I >plan on using a Hobbs switch to enrich the mixture under boost. I have >good fabricating skills and a shop to make the manifold adapters as needed. Personally, I would get rid of the 85 C3 ECM with it's slow ALDL, and use the 1227730 P4 ECM (with fast ALDL) used with the 87 and up 2.8's. The 1227730's are plentiful, because GM used it in a lot of applications, and all the code is in the EPROM. I bought an '86 'W' engine ECM (for the 2.8) and that is probably the same ECM you now have. After coaxing the code out of the ROM on the board of that C3 ECM, it turns out it has no knock sensor handling in it. You need (or at least should use) knock sensor handling on your turbo-equipped Corvair. You could put a knock sensor on each head..... >How is the code physically extracted from the ECM? I mean where do you >attach, at the ribbon cable going to the sub board? Where do you get >disassembler software to look at the code? You need to halt the ECM's processor, force an external address to the address bus and then read the data on the data bus. I did this with a bi-directional printer port and a CD4040 counter. You could probably use a PROM burner if you were creative. (Just remember not to connect the programming voltage!) The complete address and data bus is available on the edge card connector on one of the ECM boards. I know of no available 6801 disassemblers. I got a programmer at work to help me making a crude 6801 disassembler. It does the job, but requires some manual tweaking to get the resulting code right. I guess I need to fix it...... Scot Sealander FIScot@xxx.com ------------------------------ From: Carter Hendricks Date: Wed, 26 Jun 1996 19:47:57 -0700 (PDT) Subject: RE: Bosch Motronic AFM => Point - Counterpoint Thanks, Jim. On Wed, 26 Jun 1996, Land Shark wrote: > > With all due respect to Mr. Braden he has not a CLUE how Motronic works!! > > PS: Sorry to pontificate, but I've just had to UNDO too many messes that were > prompted by "experts" ... most people have no IDEA how Motronic DME works I quickly tired of shoveling after Mr. Braden, who really doesn't CARE how anything works, or how anything happened... On the other hand I think that many [most?] Alfa people prefer it his way. Its a lot easier, you know. > > They try to make it complicated when in fact it is a SIMPLE deal .. > Or maybe not easier. But there's a lot of crap out there, and for Alfas its sometimes much harder to get good information than for other cars. It took me a while to learn that some of the explanations that had been offered by certain buffoons, like Bosch tech reps, were just impossible/untrue. > I can always show you commented source code if you are from Missouri ;) > Carter, from St Louis [can I see the code?] ------------------------------ From: Carter Hendricks Date: Wed, 26 Jun 1996 19:58:46 -0700 (PDT) Subject: RE: Bosch Motronic AFM => Point - Counterpoint On Wed, 26 Jun 1996 WERNER_HAUSSMANN@xxx.com wrote: > > For the Bosch systems with the air meter, when changing the > trottle, the air meter will overshoot, the ECU will sense the rate > of change and provide an accelerator pump action. 'Loosening the spring' > will increase that accelerator pump action. That is kind of the intend of the > discussion. > Accelerator pumps are evil necessities required by carburators. --Carter ------------------------------ From: pantera@xxx.com (David Doddek) Date: Wed, 26 Jun 1996 22:58:04 -0500 Subject: someone tried to reach me? For give me for posting this to the general list. I was told from someone else that a week or so ago some one tried to reach me. Unfortunatly, my provider has changed names and so did my email address. For any one who has tried to reach pantera@xxx.com Again, sorry for the general post. David J. Doddek |pantera@xxx.com Owner SGD Electronics & Development Engr for Caterpillar |h 309 685-7965 Formula SAE Team Sidewinder 94-95 |w 309 578-2931 89 T-bird SC, 69 Fairlane w/SGD EFI |fx 217 428-4686 74 Pantera w/Electromotive Tec-II Twin turbos and Nitros | Hey, If you are going to go fast, go REEEAAL FAST. | ------------------------------ From: "The Fraser's" Date: Wed, 26 Jun 1996 23:18:43 -0500 Subject: GM Mass Airflow Sensor Hello, I'm curious if anybody has a clue as to the upper (frequency output) limit of the currently used GM mass-airflow sensor. The sensor in question is the one used on LT1/LT4's, Vortec's, etc... We've tested vehicles with up to 480 HP and the MAF sensor output is still rising with airlow demands. I really need to know if it craps out before 600 HP's worth of airflow is reached. (Assuming reasonable BSFC's and AFR's) Thanks, Brock Fraser Tuning Department Manager Hypertech, Inc. P.S- I'm new to this list, and I am quite excited about the discussions that float around... ------------------------------ From: RABBITT_Andrew@xxx.au Date: Thu, 27 Jun 1996 12:44:56 est Subject: Re: AC Delco ECM >>>You need (or at least should use) knock sensor handling on your turbo-equipped Corvair.<<< Knock sensing on an air-cooled engine, now there's a challenge! ------------------------------ From: RABBITT_Andrew@xxx.au Date: Thu, 27 Jun 1996 12:39:50 est Subject: Re: Bosch Motronic AFM => Point - Counterpoint >>> Accelerator pumps are evil necessities required by carburators. --Carter<<< Accelerator pumps are used to compensate for (amongst other things) manifold fuel film dynamics. When the manifold pressure increases, the saturated vapour pressure of components of the fuel is exceeded and so they condense to the manifold walls, thus leaning the mixture during the transient. Because the wetted area on an MPI is so much smaller than carb/manifold, this effect is not required to the same degree. To remove this effect entirely, use Direct Injection :) Andrew Rabbitt Orbital Engine Company ------------------------------ From: Land Shark Date: Wed, 26 Jun 1996 23:35:05 -0600 Subject: Re: GM Mass Airflow Sensor At 23:18 6/26/96 -0500, you wrote: >Hello, > >I'm curious if anybody has a clue as to the upper (frequency output) >limit of the currently used GM mass-airflow sensor. The sensor in >question is the one used on LT1/LT4's, Vortec's, etc... We've tested >vehicles with up to 480 HP and the MAF sensor output is still rising >with airlow demands. > >I really need to know if it craps out before 600 HP's worth of airflow >is reached. (Assuming reasonable BSFC's and AFR's) You need to send the meter up to Bob Atwood .. I think his flowbench can get that much air thru the thing ... Jim Conforti ------------------------------ From: Dave Johnson Date: Thu, 27 Jun 1996 09:00:38 +0100 Subject: Missing teeth Is there anyone out there that can answer a question for me? A lot of ECUs sense engine speed by measuring the time between pulses from a toothed wheel on the crankshaft, fair enough, I understand that. But, to get engine position they use a missing tooth to provide a datum mark. What I want to know is how exactly do thay know when they are at that datum mark? For instance, when first starting the engine do they compare the time between pulses and when they get a much larger time compared to previous ones they think oh I'm at the datum! I just can't quite get my head around it at the moment. It's probably quite staight forward and logical but I can't see it. Thanks in advance, Dave Johnson email:- dajohnson@xxx.com begin 600 WINMAIL.DAT M>)\^(BD(`0:0" `$```````!``$``0>0!@`(````Y 0```````#H``$(@ <` M& ```$E032Y-:6-R;W-O9G0@xxx.#DS M140`Z $!(( #``X```#,!P8`&P`)````)@xxx.````S <&`!L` M"0```"8`! `G`0$-@ 0``@````(``@`!!( !``X```!-:7-S:6YG('1E971H M`!0%`0.0!@xxx.[`1X`"! !````90```$E35$A% M4D5!3EE/3D5/55142$52151(051#04Y!3E-715)!455%4U1)3TY&3U)-13]! M3$]43T9%0U534T5.4T5%3D=)3D534$5%1$)9345!4U5224Y'5$A%5$E-14)% M5%=%14X``````P`F```````+`",```````L`*0```````P`V```````>`' ` M`0````X```!-:7-S:6YG('1E971H`````@%Q``$````6`````;MC_KJQP&U< M/L09$<^F;@" 7TCB(P```P`&$*<*KW$#``<010(```,`$! ``````P`1$ `` M```"`0D0`0```*$"``"=`@``SP,``$Q:1G51=!1B_P`*`0\"%0*D`^0%ZP*# M`% W`O,&M *#,@/%`@!C:,$*P'-E=# @!Q,"@/Y]"H (SPG9`H *A LW$C)) M`= @200@=&@$D&7Z( !P>0(@%[ (8 5 %W2U%W!A!4!C`Y$`<7<$D(D7P"!Q M"E!S=&D"(.X@`A %P > /PJC"H4*@ Q!(!1 !4!O9B!%?$-5!" 3$ " %[ ) M\&<3"X 7L'-P">!D(&+R>1K!87,(<1TP%V(78!\'<1W@$R 9H GP('!UGFP3 M$ 0@`U(9T71O'!#K%X =T'<7@&4#(!IA'L*S!0``<&MS$N !@"P:@$\+< 7 M"? (8&=H(J!)^"!U;@xxx.(X+B!"&% BH""P(&?S$R =%G!O`) : M0Q=Q'@#V=1SQ&>!M! $>@R#")0*R< -@=FD-L!G19!D`1G4@< # `"MC?R$Q M)F4*P!>Q&&(9`2CH/YP@1@6Q"X D`F-E(J#]+7-F(N :,!RP`9 `(!Z&[QTE M+*,FH06@;0JQ&,(>[]\?\R0B+7@E0B<1=1+0&_!_"L E0 7 ,Z,RY21!*")E M_RAP"& $(!@!%U,>`!=P"X#F:Q@P)_!))R!Q&&,HU-HA(X%J)M 9$R<%0!H` MMR8@xxx.>8$8 > `C"Q*8U)="<$("A!8@&@ M]RQQ.Z0D`6DC4 5 &I$JX+\+(#33%$ =0!DP`R!B&%&_(Y [1!,0%[ F("F- M5!+@9R(Q+\$7P&1V,!,;#$3T8787L$HY@ " `B ;#*9E`, #$#HM*-%J1I1> M0 VP*7 RX1L%?4G@````0 `',!!4L;K^8[L!0 `(,!!4L;K^8[L!`P`--/T_ M```"`10T`0```! ```!4E*' *7\0&Z6'" `K*B47'@`]``$````!```````` #`*L8 ` end ------------------------------ From: Craig Pugsley Date: Thu, 27 Jun 1996 18:28:24 +1000 (EST) Subject: Re: AC Delco ECM > > >>>You need (or at least should use) knock sensor handling on your > turbo-equipped Corvair.<<< > > Knock sensing on an air-cooled engine, now there's a challenge! > Excuse my ignorance, but why is this difficult? Craig. pugsley@xxx.au ------------------------------ End of DIY_EFI Digest V1 #181 ***************************** 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".