DIY_EFI Digest Thursday, 21 January 1999 Volume 04 : Number 049 In this issue: Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: heated O2 sensor circuit question Re: TPI on a 406 Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: TPI on a 406 Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Knock Sensor Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: heated O2 sensor circuit question Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Heated Oxygen Sensor Re: DFI, Batch Fire, and other myths Re: DFI, Batch Fire, and other myths Re: Knock Sensor Re: TPI on a 406 See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: andy quaas Date: Thu, 21 Jan 1999 05:53:38 -0800 (PST) Subject: Re: DFI, Batch Fire, and other myths Is it true that none of the firing methods actually time the injector to the intake stroke of that cylinder? I would think that injecting fuel on the other strokes would be a waste. Andy - ---Sandy wrote: > > I think that injection of all the fuel during a period has some SMOG/Econ > bennifits, but can't remember if any power was gained (anyone?). Others > have stated that the evaporation of the fuel sitting on the closed valve is > better then squirting raw liquid fuel (hard to burn) into a cylinder. I > think that is why you don't see much power difference between SFI and BATCH > systems. > > Sandy > > At 10:17 PM 1/20/99 -0600, you wrote: > > > > > >Ward Spoonemore wrote: > > > >> Tom > >> Your Edelbrock ProFlo is typical on several other EFI system's > >> actualy the tests I have run show little on no differace between L/R and > >> other systems. > >> In fact all EFI are on almost 100% at or near WOT. > >> Ward > > > >There is an ongoing discussion about the need to inject all (or most) of the > >fuel while the intake valve is open, probably starting before the valve > >opens and ending before it is closed. It would require large P&H injectors > >and lotta of pressure. > > > >Any ideas or comments (or experiences). Regards Tom > > > > > > _________________________________________________________ DO YOU YAHOO!? Get your free @xxx.com ------------------------------ From: "Gary Derian" Date: Thu, 21 Jan 1999 08:57:24 -0500 Subject: Re: DFI, Batch Fire, and other myths Recent research on fuel droplet sizes has shown that injecting fuel onto a closed intake valve, then letting a shot of exhaust hit it when the valve opens (reversion) produces better and smaller droplets than the injector itself can generate. See the SAE Journal from a month or two ago. With this info, SFI could be used to insure that all the fuel is injected while the valve is closed, not open. How are the SFI systems actually timed? Gary Derian ------------------------------ From: Ken Kelly Date: Thu, 21 Jan 1999 08:55:27 -0500 Subject: Re: DFI, Batch Fire, and other myths My comment was in reference to the idea that using two O2 sensors implied you could have two independent fuel controls for the two injector drivers. The early ECM's & O2 sensors were too slow to be able to react to individual cylinder firings. There was an implication that the two O2 sensors would allow independent fuel controls for the two injector drivers. Since each O2 sensor is on a different bank, the injectors would have to be grouped by bank to get this independence. That would require some injectors to have their whole injection cycle completed while the intake valve is closed. I can't see how that would cause good fuel mixture. I would think there would be a lot of fuel seperation and pooling in the inlets that always fired while the valve was closed. I would think at least from an emmisions point that GM would gain more by having the injectors ganged so that they fire closer too the intake valve opening, than having them ganged by cylinder bank.. Ken Tom Sharpe wrote: > > Ken Kelly wrote: > > > This only makes sense if the injectors are fired as left > > bank and right bank. I would think you would gain more > > benefit by grouping them in firing order rather than by > > bank. > > My ProFlow fires 4 sets of 2 injectors 1-8, 4-3, 6-5, 7-2. foue > circuits/timers/drivers, one O2 sensor. Tom ------------------------------ From: Mike Brown Date: Thu, 21 Jan 1999 06:12:30 -0800 Subject: Re: DFI, Batch Fire, and other myths Tom Sharpe wrote: > > Ken Kelly wrote: > > > This only makes sense if the injectors are fired as left > > bank and right bank. I would think you would gain more > > benefit by grouping them in firing order rather than by > > bank. > > My ProFlow fires 4 sets of 2 injectors 1-8, 4-3, 6-5, 7-2. foue > circuits/timers/drivers, one O2 sensor. Tom Actually Tom, your ProFlow does fire the injectors in this order but not in sync with the cylinders. Wherever the motor happens to start cranking over it starts spraying. This is due to a bug in the code that does not detect the #1 cylinder (the narrow pulse from the distributor). I have reverse engineered the hardware and firmware on this system and have corrected this bug. If anybody out there has an Edelbrock ProFlow and is interested in working together to improve it let me know as I have functional schematics and documented source code (the code is full of bugs I might add). Been working steadily on this for over 7 months. Mike ------------------------------ From: Mike Brown Date: Thu, 21 Jan 1999 06:18:05 -0800 Subject: Re: DFI, Batch Fire, and other myths Shannen Durphey wrote: > > Tom, is there any chance that you know what the resistance of the > injectors is? > Shannen > > diy_efi@xxx.edu wrote: > > > > Ken Kelly wrote: > > > > > This only makes sense if the injectors are fired as left > > > bank and right bank. I would think you would gain more > > > benefit by grouping them in firing order rather than by > > > bank. > > > > My ProFlow fires 4 sets of 2 injectors 1-8, 4-3, 6-5, 7-2. foue > > circuits/timers/drivers, one O2 sensor. Tom Shannen, I don't have my notes in front of me at work here but if my memory serves me I beleive they are arround 25 ohms DC resistance. I will confirm this and let you know. Mike ------------------------------ From: Mike Brown Date: Thu, 21 Jan 1999 06:25:50 -0800 Subject: Re: heated O2 sensor circuit question Ed wrote: > > I plan on relocating my O2 sensor further down into the header since the > original spot reads off only 2 of the 4 cylinders. Thing is, the > original sensor is a single wire, and I think I'd need a heated one for > the new location. > Any idea how to wire the heater circuit? Is it safe to wire the circuit > to a switched (engine on) power source or was the heaer designed to shut > off once it reaches operating temp? > > -Ed Ed, On my Edelbrock/Webber ProFlow the heated sensor is powered off the same circuit as the fuel pump. I think that was done only for wiring harness convenience. I see no reason why it couldn't be powered thru the ignition switch. I believe it is a Bosch unit from a Ford. Three wires, +12v, ground, O2 sensor output. Mike ------------------------------ From: Ken Kelly Date: Thu, 21 Jan 1999 09:21:08 -0500 Subject: Re: TPI on a 406 V8 Camaro's have usually had a rough life. There is a very good chance that peices you remove from an 85 camaro didn't come from the factory in that car. Do you know the history of the car! Was it on its 1st 2nd or 3rd engine? Ken Shannen Durphey wrote: > > Hey, I might have thought of a clue for ya. The 85 TPI had all the > intake bolt holes at the same angle, and will fit on any 85 and older > heads. 86 is usually the break year. If the center two bolts are at > a different angle that the rest, you've probably got an 86+ unit. > Shannen > > diy_efi@xxx.edu wrote: > > > > OK I just picked up all the TPI hardware. The ECU turned out > > to be a 165 unit but the guy I bought it from swears it came > > out of a 1985 Camaro. Is it possible that the 165 was used > > toward the end of the year? > > > > The harness is a complete stock harness, so I have a lot of > > ringing to do to identify all the plugs and non-essential > > portions of the harness. > > > > Charles Brooks ------------------------------ From: "Walter Sherwin" Date: Thu, 21 Jan 1999 09:38:26 -0800 Subject: Re: DFI, Batch Fire, and other myths Why would it be a problem to deal with lots of boost when all the injectors (or a bunch) are opened at the same time? Is the problem associated with pump pressure versus flow capacity, or with the actual manifold fuel dynamics? Just curious. Walt. - -----Original Message----- From: Sandy To: diy_efi@xxx.edu> Date: Wednesday, January 20, 1999 9:37 PM Subject: RE: DFI, Batch Fire, and other myths >One thing that is very inportant to remember about injection CIS vs Batch >vs SFI is on cars that have boost it is a problem to deal with lots of >boost when all injectors (or a bunch) are opened at the same time. SFI does >much better in those situations, as it is easier to deal with the fuel >pressure vs boost pressure problems. The ideal system for me that would be >very easy to do was a concept that I posted a millenium ago, just do a SFI >Batch system (Pat Pend, (c) etc), where they are not in sync to anything, >but follow a SFI pattern. No engine sensor or sync is required (read >simple) and you get most all of the needed SFI benny's. No fuss no muss. >The over-engineering problem has plagued the efi332 project for sometime, >and getting something simple running is the way to go! > >Some rambelings > >Sandy ------------------------------ From: Mike Brown Date: Thu, 21 Jan 1999 07:02:20 -0800 Subject: Re: DFI, Batch Fire, and other myths Gary Derian wrote: > > Recent research on fuel droplet sizes has shown that injecting fuel onto a > closed intake valve, then letting a shot of exhaust hit it when the valve > opens (reversion) produces better and smaller droplets than the injector > itself can generate. See the SAE Journal from a month or two ago. > > With this info, SFI could be used to insure that all the fuel is injected > while the valve is closed, not open. How are the SFI systems actually > timed? > > Gary Derian Gary, On the Edelbrock ProFlow it is a function of RPM only. Not much resolution in the system so it can only advance the injector timing in 90 degree (crank degrees) chunks. The break-points seem to be set up so that most of the time the injector has finished firing before the intake opens. Some situations, like low rpm and high load it will still be spraying while the valve is opening. Mike ------------------------------ From: steve ravet Date: Thu, 21 Jan 1999 09:37:18 -0600 Subject: Re: TPI on a 406 The factory manuals are good about showing diagrams of every plug, their pinouts and purpose. - --steve Charles Brooks wrote: > > OK I just picked up all the TPI hardware. The ECU turned out > to be a 165 unit but the guy I bought it from swears it came > out of a 1985 Camaro. Is it possible that the 165 was used > toward the end of the year? > > The harness is a complete stock harness, so I have a lot of > ringing to do to identify all the plugs and non-essential > portions of the harness. > > Charles Brooks ------------------------------ From: bearbvd@xxx.net (Greg Hermann) Date: Thu, 21 Jan 1999 08:39:57 -0700 Subject: Re: DFI, Batch Fire, and other myths Hi-- I just couldn't resist jumping beck into this one!! Yes, Andy, you are right. Problems for most efi are: 1. Most injectors do not have enough dynamic range to be able to inject all the fuel for WOT power during just 80 to 100 degrees of crank rotation AND be able to turn down far enough (Can't go to a short enough pulse width) to inject a small enough quantity of fuel for proper fueling at idle. 2. Most efi injectors do not atomize the fuel very well at all, period. So tricks such as squirting fuel against the back side of a closed, hot intake valve are used to get the fuel vaporized. (Vaporized is distinctly different from atomized, this is not just a semantic point.) There are OBVIOUS benefits to timing a squirt of WELL ATOMIZED fuel with high inhale velocity in the intake ports. Anybody who doubts this statement, get back to me after perusing some dyno data for an engine, any properly tuned engine, equipped with an IR intake manifold with Weber, Delorto, or Mikuni/Solex IR carbs. Pay particular attention to how LOW the bsfc numbers are when it is tuned properly. Try the same engine with either a standard carb and wet manifold or TPI. When running the TPI test, restrict the Manifold runners with a choke the same size as whatever venturis were used in the IR carbs, so that air flow is equal. We all know that the IR carbs will seriously outperform the wet manifold. What is not so obvious to all is that: 1. The IR carbs will give lower bsfc at part throttle than the TPI, because they atomize the fuel so much better. 2. The IR carbs will geve significantly more power, together with lower bsfc, (remember, air flow has been equalized) at WOT both because they atomize the fuel very well, and because they time the shot of fuel with high inhale velocity in the port. There would be a lot less debate about this if anybody had ever bothered to set up a true, change only one variable at a time, test of it. (I don't know of any such tests.) There are several very clear performance, economy, durability, and thermodynamic benefits to getting well atomized, but not vaporized, fuel inside the cylinder and getting the intake valve closed before much vaporization takes place. The finer the atomization, the better, and the less vaporization, the better. Good IR carbs do this pretty well. Efi, (meaning TPI) despite all of its obvious airflow and metering accuracy benefits does not do these two things very well at all with current injector technology. There are lots of folks in the industry working on developing ways to make efi do these things better. I am working on the same thing as a hobby. When I get an engine built, and get some test results, I will share them. But some money is definitely going where my mouth is!!! That is so because I believe that the above outline of the situation is sound engineering/science and I want a better performing engine(s). Regards, Greg >Is it true that none of the firing methods actually time the injector >to the intake stroke of that cylinder? I would think that injecting >fuel on the other strokes would be a waste. > >Andy > > >---Sandy wrote: >> >> I think that injection of all the fuel during a period has some >SMOG/Econ >> bennifits, but can't remember if any power was gained (anyone?). >Others >> have stated that the evaporation of the fuel sitting on the closed >valve is >> better then squirting raw liquid fuel (hard to burn) into a >cylinder. I >> think that is why you don't see much power difference between SFI >and BATCH >> systems. >> >> Sandy >> >> At 10:17 PM 1/20/99 -0600, you wrote: >> > >> > >> >Ward Spoonemore wrote: >> > >> >> Tom >> >> Your Edelbrock ProFlo is typical on several other EFI system's >> >> actualy the tests I have run show little on no differace between >L/R and >> >> other systems. >> >> In fact all EFI are on almost 100% at or near WOT. >> >> Ward >> > >> >There is an ongoing discussion about the need to inject all (or >most) of the >> >fuel while the intake valve is open, probably starting before the >valve >> >opens and ending before it is closed. It would require large P&H >injectors >> >and lotta of pressure. >> > >> >Any ideas or comments (or experiences). Regards Tom >> > >> > >> >> > >_________________________________________________________ >DO YOU YAHOO!? >Get your free @xxx.com ------------------------------ From: bearbvd@xxx.net (Greg Hermann) Date: Thu, 21 Jan 1999 08:45:41 -0700 Subject: Re: DFI, Batch Fire, and other myths >Why would it be a problem to deal with lots of boost when all the injectors >(or a bunch) are opened at the same time? Is the problem associated with >pump pressure versus flow capacity, or with the actual manifold fuel >dynamics? Just curious. > >Walt. Fuel flow dynamics (hammer, etc.,) in the fuel rails. Pump curve enters into it as well, but not as strongly. Greg > >-----Original Message----- >From: Sandy >To: diy_efi@xxx.edu> >Date: Wednesday, January 20, 1999 9:37 PM >Subject: RE: DFI, Batch Fire, and other myths > > >>One thing that is very inportant to remember about injection CIS vs Batch >>vs SFI is on cars that have boost it is a problem to deal with lots of >>boost when all injectors (or a bunch) are opened at the same time. SFI does >>much better in those situations, as it is easier to deal with the fuel >>pressure vs boost pressure problems. The ideal system for me that would be >>very easy to do was a concept that I posted a millenium ago, just do a SFI >>Batch system (Pat Pend, (c) etc), where they are not in sync to anything, >>but follow a SFI pattern. No engine sensor or sync is required (read >>simple) and you get most all of the needed SFI benny's. No fuss no muss. >>The over-engineering problem has plagued the efi332 project for sometime, >>and getting something simple running is the way to go! >> >>Some rambelings >> >>Sandy ------------------------------ From: "Guenther,Max" Date: Thu, 21 Jan 1999 11:03:03 -0500 Subject: Knock Sensor Does anyone know if the knock sensor module(ESC)is inside the ECM or >seperate on a 90-91 vette tpi. ------------------------------ From: dave.williams@xxx.us (Dave Williams) Date: Thu, 21 Jan 1999 09:55:00 -0500 Subject: Re: DFI, Batch Fire, and other myths - -> Recent research on fuel droplet sizes has shown that injecting fuel - -> onto a closed intake valve, then letting a shot of exhaust hit it - -> when the valve opens (reversion) produces better and smaller droplets - -> than the injector Sure. But most engines simply squirt their fuel directly onto the floor or wall of the intake port four or five inches away from the valve. Take a look at any American V8 or most V6s, for example. To get the injector to point at the valve requires a straight port from the valve to the injector, with the air path curved down below the injector's line of sight. Very, very few engines do this. ==dave.williams@xxx.us====================================== I've got a secret / I've been hiding / under my skin / | Who are you? my heart is human / my blood is boiling / my brain IBM | who, who? =================================== http://home1.gte.net/42/index.htm ------------------------------ From: rauscher@xxx.com Date: Thu, 21 Jan 99 11:14:14 -0500 Subject: Re: DFI, Batch Fire, and other myths Tom Sharpe wrote: > >My ProFlow fires 4 sets of 2 injectors 1-8, 4-3, 6-5, 7-2. foue >circuits/timers/drivers, one O2 sensor. Tom > In reading the archives, I thought the Pro-Flo used a '747 ECM, which only has two drivers. Maybe a '749 is used, with 4 drivers? I've tried to search the archive's, but to no avail... BobR. - -- ------------------------------ From: LS Date: Thu, 21 Jan 1999 12:03:00 -0500 Subject: Re: heated O2 sensor circuit question All oxygen sensors 1,3,4 wire are the same in principal. 3 and 4 wire are heated. 4 wire has a signal ground instaed of using exhaust manifold for ground. The heating element lowers its current consumpiton with an increase in its temperature. So it is self regulating, and does not require special control. Good Luck Len. ------------------------------ From: Shannen Durphey Date: Thu, 21 Jan 1999 12:04:03 -0500 Subject: Re: DFI, Batch Fire, and other myths The sometimes less than accurate GM classes I've attended teach that injection should occur when the intake valve is closed,and be completed immediately prior to intake valve opening. This would make use of the heat in the head of the valve help keep fuel from pooling. This was mentioned earlier. This might be GM's approach to sefi. According to a service bulletin, the 3.8l engine suffers from carbon accumulation on the back of the intake valve which significantly reduces performance. I've seen the effects. It's very similar to losing the accelerator pump on a carb'ed engine, and the exhaust is excessively rich. My thought was the carbon is insulating the valve, preventing vaporization. Shannen diy_efi@xxx.edu wrote: > > Recent research on fuel droplet sizes has shown that injecting fuel onto a > closed intake valve, then letting a shot of exhaust hit it when the valve > opens (reversion) produces better and smaller droplets than the injector > itself can generate. See the SAE Journal from a month or two ago. > > With this info, SFI could be used to insure that all the fuel is injected > while the valve is closed, not open. How are the SFI systems actually > timed? > > Gary Derian ------------------------------ From: Sandy Date: Thu, 21 Jan 1999 09:16:32 -0800 Subject: Re: DFI, Batch Fire, and other myths It becomes hard for the pressure that gets back into the fuel system, ie, 14lbs of boost will change the flow as instead of squirting against a vaccum or light pressure, they now have to overcome what ever the boost is. Sure boost adjusted regulators will help, but it get difficult to overcome the dynamics of the pulses of each injector. Think of this if I have a pump that does injection at 15lbs of fuel pressure and I have 15lbs of boost, the fuel will not come out of the injector. Multiply this problem with more open injectors and the fuel rail becomes very hard to regulate. Sandy At 09:38 AM 1/21/99 -0800, you wrote: >Why would it be a problem to deal with lots of boost when all the injectors >(or a bunch) are opened at the same time? Is the problem associated with >pump pressure versus flow capacity, or with the actual manifold fuel >dynamics? Just curious. > >Walt. ------------------------------ From: andy quaas Date: Thu, 21 Jan 1999 09:14:25 -0800 (PST) Subject: Re: DFI, Batch Fire, and other myths Doesn't a venturi atomize fuel very well in any case? As stupid as it sounds, why not make an intake that has a venturi for each port and feed the fuel to the venturi at each intake port. You'd have a lota throttle shafts and such, but it would atomize the fuel better, no? What mechanical devices atomize fuel well? How well does a mechanical injection atomize fuel? Andy p.s. what does IR stand for? - ---Greg Hermann wrote: > > Hi-- > > I just couldn't resist jumping beck into this one!! > > Yes, Andy, you are right. Problems for most efi are: > > 1. Most injectors do not have enough dynamic range to be able to inject > all the fuel for WOT power during just 80 to 100 degrees of crank rotation > AND be able to turn down far enough (Can't go to a short enough pulse > width) to inject a small enough quantity of fuel for proper fueling at > idle. > > 2. Most efi injectors do not atomize the fuel very well at all, period. So > tricks such as squirting fuel against the back side of a closed, hot intake > valve are used to get the fuel vaporized. (Vaporized is distinctly > different from atomized, this is not just a semantic point.) > > There are OBVIOUS benefits to timing a squirt of WELL ATOMIZED fuel with > high inhale velocity in the intake ports. Anybody who doubts this > statement, get back to me after perusing some dyno data for an engine, any > properly tuned engine, equipped with an IR intake manifold with Weber, > Delorto, or Mikuni/Solex IR carbs. Pay particular attention to how LOW the > bsfc numbers are when it is tuned properly. Try the same engine with either > a standard carb and wet manifold or TPI. When running the TPI test, > restrict the Manifold runners with a choke the same size as whatever > venturis were used in the IR carbs, so that air flow is equal. We all know > that the IR carbs will seriously outperform the wet manifold. What is not > so obvious to all is that: > > 1. The IR carbs will give lower bsfc at part throttle than the TPI, > because they atomize the fuel so much better. > > 2. The IR carbs will geve significantly more power, together with lower > bsfc, (remember, air flow has been equalized) at WOT both because they > atomize the fuel very well, and because they time the shot of fuel with > high inhale velocity in the port. > > There would be a lot less debate about this if anybody had ever bothered to > set up a true, change only one variable at a time, test of it. (I don't > know of any such tests.) > > There are several very clear performance, economy, durability, and > thermodynamic benefits to getting well atomized, but not vaporized, fuel > inside the cylinder and getting the intake valve closed before much > vaporization takes place. The finer the atomization, the better, and the > less vaporization, the better. Good IR carbs do this pretty well. Efi, > (meaning TPI) despite all of its obvious airflow and metering accuracy > benefits does not do these two things very well at all with current > injector technology. > > There are lots of folks in the industry working on developing ways to make > efi do these things better. I am working on the same thing as a hobby. When > I get an engine built, and get some test results, I will share them. But > some money is definitely going where my mouth is!!! That is so because I > believe that the above outline of the situation is sound > engineering/science and I want a better performing engine(s). > > Regards, Greg > > > > >Is it true that none of the firing methods actually time the injector > >to the intake stroke of that cylinder? I would think that injecting > >fuel on the other strokes would be a waste. > > > >Andy > > > > > >---Sandy wrote: > >> > >> I think that injection of all the fuel during a period has some > >SMOG/Econ > >> bennifits, but can't remember if any power was gained (anyone?). > >Others > >> have stated that the evaporation of the fuel sitting on the closed > >valve is > >> better then squirting raw liquid fuel (hard to burn) into a > >cylinder. I > >> think that is why you don't see much power difference between SFI > >and BATCH > >> systems. > >> > >> Sandy > >> > >> At 10:17 PM 1/20/99 -0600, you wrote: > >> > > >> > > >> >Ward Spoonemore wrote: > >> > > >> >> Tom > >> >> Your Edelbrock ProFlo is typical on several other EFI system's > >> >> actualy the tests I have run show little on no differace between > >L/R and > >> >> other systems. > >> >> In fact all EFI are on almost 100% at or near WOT. > >> >> Ward > >> > > >> >There is an ongoing discussion about the need to inject all (or > >most) of the > >> >fuel while the intake valve is open, probably starting before the > >valve > >> >opens and ending before it is closed. It would require large P&H > >injectors > >> >and lotta of pressure. > >> > > >> >Any ideas or comments (or experiences). Regards Tom > >> > > >> > > >> > >> > > > >_________________________________________________________ > >DO YOU YAHOO!? > >Get your free @xxx.com > > > _________________________________________________________ DO YOU YAHOO!? Get your free @xxx.com ------------------------------ From: Shannen Durphey Date: Thu, 21 Jan 1999 12:31:44 -0500 Subject: Re: DFI, Batch Fire, and other myths The same but different. Edelbrock Pro-flo is a pfi setup for 85 and older engines which uses it's own ecu. Edelbrock also makes a pfi conversion for tbi pickups which uses the stock wiring harness and computer. Shannen diy_efi@xxx.edu wrote: > > Tom Sharpe wrote: > > > >My ProFlow fires 4 sets of 2 injectors 1-8, 4-3, 6-5, 7-2. foue > >circuits/timers/drivers, one O2 sensor. Tom > > > > In reading the archives, I thought the Pro-Flo used a '747 ECM, > which only has two drivers. Maybe a '749 is used, with 4 drivers? > > I've tried to search the archive's, but to no avail... > > BobR. > > -- ------------------------------ From: "Trevor Jones" Date: Thu, 21 Jan 1999 11:41:52 -0600 Subject: Heated Oxygen Sensor I'm not subscribed to this list yet but I'm hoping that some of you EFI experts can help me out a little. Since I'm not subscribed yet, any comments need to be written directly to jones.trevor@xxx. I'm putting a Chevy 350 TBI into my '88 Jeep Wrangler. The engine that I'm using came from a '95 suburban with the 4LE60 tranny. It has what GM calls a heated oxygen sensor instead of a standard oxygen sensor(difference obviously being it has a positive lead and a ground to "heat" it up as well as the sensor wire going to the PCM). This oxygen sensor is located on the exhaust pipe AFTER the two banks of cylinders come together with a Y-pipe. Would it be a problem if I installed the oxygen sensor on only one bank of cylinders, or will this adversely affect the computer because it thinks it's reading from BOTH cylinder banks? Using only one bank of cylinders, it would technically have a low reading and think the engine is running too lean, bumping up the fuel mixture and actually making the engine run too rich now. Since the engine is getting dual exhaust it isn't an option to put the sensor on a pipe reading from both cylinder banks. Is this going to make a difference or will it be so minor that it won't really matter?? Another option is to use a regular oxygen sensor(non-heated) that is made to screw into the exhaust manifold on one side. However, do the readings of these two different kinds of sensors differ, throwing the PCM way off? Now the PCM would think it's getting a reading from a heated oxygen sensor off both cylinder banks, when it's really just getting the reading from a regular oxygen sensor on one cylinder bank. Could the PCM or the chip possibly be different depending on what type of oxygen sensor it had, or would it function the same with either sensor?? Thanks for any help, it is GREATLY appreciated. TJ Jones ------------------------------ From: "Bruce Plecan" Date: Thu, 21 Jan 1999 13:04:24 -0500 Subject: Re: DFI, Batch Fire, and other myths - -----Original Message----- From: andy quaas To: diy_efi@xxx.edu> Date: Thursday, January 21, 1999 12:28 PM Subject: Re: DFI, Batch Fire, and other myths Check out Barry Gant's EFI system. It uses venturi Bruce >Doesn't a venturi atomize fuel very well in any case? As stupid as it >sounds, why not make an intake that has a venturi for each port and >feed the fuel to the venturi at each intake port. You'd have a lota >throttle shafts and such, but it would atomize the fuel better, no? >What mechanical devices atomize fuel well? How well does a mechanical >injection atomize fuel? > >Andy > >p.s. what does IR stand for? > > >---Greg Hermann wrote: >> >> Hi-- >> >> I just couldn't resist jumping beck into this one!! >> >> Yes, Andy, you are right. Problems for most efi are: >> >> 1. Most injectors do not have enough dynamic range to be able to >inject >> all the fuel for WOT power during just 80 to 100 degrees of crank >rotation >> AND be able to turn down far enough (Can't go to a short enough pulse >> width) to inject a small enough quantity of fuel for proper fueling at >> idle. >> >> 2. Most efi injectors do not atomize the fuel very well at all, >period. So >> tricks such as squirting fuel against the back side of a closed, hot >intake >> valve are used to get the fuel vaporized. (Vaporized is distinctly >> different from atomized, this is not just a semantic point.) >> >> There are OBVIOUS benefits to timing a squirt of WELL ATOMIZED fuel >with >> high inhale velocity in the intake ports. Anybody who doubts this >> statement, get back to me after perusing some dyno data for an >engine, any >> properly tuned engine, equipped with an IR intake manifold with Weber, >> Delorto, or Mikuni/Solex IR carbs. Pay particular attention to how >LOW the >> bsfc numbers are when it is tuned properly. Try the same engine with >either >> a standard carb and wet manifold or TPI. When running the TPI test, >> restrict the Manifold runners with a choke the same size as whatever >> venturis were used in the IR carbs, so that air flow is equal. We >all know >> that the IR carbs will seriously outperform the wet manifold. What >is not >> so obvious to all is that: >> >> 1. The IR carbs will give lower bsfc at part throttle than the TPI, >> because they atomize the fuel so much better. >> >> 2. The IR carbs will geve significantly more power, together with >lower >> bsfc, (remember, air flow has been equalized) at WOT both because >they >> atomize the fuel very well, and because they time the shot of fuel >with >> high inhale velocity in the port. >> >> There would be a lot less debate about this if anybody had ever >bothered to >> set up a true, change only one variable at a time, test of it. (I >don't >> know of any such tests.) >> >> There are several very clear performance, economy, durability, and >> thermodynamic benefits to getting well atomized, but not vaporized, >fuel >> inside the cylinder and getting the intake valve closed before much >> vaporization takes place. The finer the atomization, the better, and >the >> less vaporization, the better. Good IR carbs do this pretty well. Efi, >> (meaning TPI) despite all of its obvious airflow and metering accuracy >> benefits does not do these two things very well at all with current >> injector technology. >> >> There are lots of folks in the industry working on developing ways >to make >> efi do these things better. I am working on the same thing as a >hobby. When >> I get an engine built, and get some test results, I will share them. >But >> some money is definitely going where my mouth is!!! That is so >because I >> believe that the above outline of the situation is sound >> engineering/science and I want a better performing engine(s). >> >> Regards, Greg >> >> >> >> >Is it true that none of the firing methods actually time the injector >> >to the intake stroke of that cylinder? I would think that injecting >> >fuel on the other strokes would be a waste. >> > >> >Andy >> > >> > >> >---Sandy wrote: >> >> >> >> I think that injection of all the fuel during a period has some >> >SMOG/Econ >> >> bennifits, but can't remember if any power was gained (anyone?). >> >Others >> >> have stated that the evaporation of the fuel sitting on the closed >> >valve is >> >> better then squirting raw liquid fuel (hard to burn) into a >> >cylinder. I >> >> think that is why you don't see much power difference between SFI >> >and BATCH >> >> systems. >> >> >> >> Sandy >> >> >> >> At 10:17 PM 1/20/99 -0600, you wrote: >> >> > >> >> > >> >> >Ward Spoonemore wrote: >> >> > >> >> >> Tom >> >> >> Your Edelbrock ProFlo is typical on several other EFI system's >> >> >> actualy the tests I have run show little on no differace between >> >L/R and >> >> >> other systems. >> >> >> In fact all EFI are on almost 100% at or near WOT. >> >> >> Ward >> >> > >> >> >There is an ongoing discussion about the need to inject all (or >> >most) of the >> >> >fuel while the intake valve is open, probably starting before the >> >valve >> >> >opens and ending before it is closed. It would require large P&H >> >injectors >> >> >and lotta of pressure. >> >> > >> >> >Any ideas or comments (or experiences). Regards Tom >> >> > >> >> > >> >> >> >> >> > >> >_________________________________________________________ >> >DO YOU YAHOO!? >> >Get your free @xxx.com >> >> >> > >_________________________________________________________ >DO YOU YAHOO!? >Get your free @xxx.com > ------------------------------ From: "Gary Derian" Date: Thu, 21 Jan 1999 13:04:13 -0500 Subject: Re: DFI, Batch Fire, and other myths Carbon buildup on the back if an intake valve absorbs fuel. During a transition from part to full throttle, the carbon absorbs some of the added fuel causing a momentary lean condition, just like a wet flow manifold. Gary Derian >The sometimes less than accurate GM classes I've attended teach that >injection should occur when the intake valve is closed,and be >completed immediately prior to intake valve opening. This would make >use of the heat in the head of the valve help keep fuel from pooling. >This was mentioned earlier. This might be GM's approach to sefi. >According to a service bulletin, the 3.8l engine suffers from carbon >accumulation on the back of the intake valve which significantly >reduces performance. I've seen the effects. It's very similar to >losing the accelerator pump on a carb'ed engine, and the exhaust is >excessively rich. My thought was the carbon is insulating the valve, >preventing vaporization. >Shannen > >diy_efi@xxx.edu wrote: >> >> Recent research on fuel droplet sizes has shown that injecting fuel onto a >> closed intake valve, then letting a shot of exhaust hit it when the valve >> opens (reversion) produces better and smaller droplets than the injector >> itself can generate. See the SAE Journal from a month or two ago. >> >> With this info, SFI could be used to insure that all the fuel is injected >> while the valve is closed, not open. How are the SFI systems actually >> timed? >> >> Gary Derian ------------------------------ From: "Bruce Plecan" Date: Thu, 21 Jan 1999 13:12:59 -0500 Subject: Re: Knock Sensor - -----Original Message----- From: Guenther,Max To: 'diy_efi@xxx.edu> Date: Thursday, January 21, 1999 11:28 AM Subject: Knock Sensor If a 1227730, or 1227727ecm, there is no external ESC Module. Bruce > >Does anyone know if the knock sensor module(ESC)is inside the ECM or >>seperate on a 90-91 vette tpi. > ------------------------------ From: Ludis Langens Date: Thu, 21 Jan 1999 09:08:34 -0800 Subject: Re: TPI on a 406 "Bruce Plecan" > I'd check the pinout real close, the 6870, and 165 both have two > connector ecms, and maybe someone threw the 165 inna pile, > thinking it was the same thing. I don't know if there is a > difference in pinouts, but if the harness doesn't match the > pinout for a 165 then that's you answer, there is a 165 pinout > at 332 FTP. The pinouts are subtly different. From memory, A11 & B11 are analog inputs (MAT, etc.) in one and grounds in the other. Also, one of the EST signals is moved. The '165 is closer to the pinout of a '747. Why couldn't GM be consistent? - -- Ludis Langens ludis (at) cruzers (dot) com Mac, Fiero, & engine controller goodies: http://www.cruzers.com/~ludis/ ------------------------------ End of DIY_EFI Digest V4 #49 **************************** 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".