DIY_EFI Digest Saturday, November 20 1999 Volume 04 : Number 651 In this issue: We're Obsolete (Almost) flowbench Speed sensor Re: Speed sensor Re: Spark retard for EEC-V (DIS) Spark retard continued See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Fri, 19 Nov 1999 15:47:56 -0500 From: "Bruce Plecan" Subject: We're Obsolete (Almost) New Street Rodder (Dec 99) details the new Ram Jet EFI from GM. Also, comes with the MEFI3 ECM. It was designed for doing marine calibrations. It's palm sized. The Ram Jet looks kinda like the ol Mech vette set-up. SBC, and BBC, using vortec fast burn heads. Grumpy ------------------------------ Date: Fri, 19 Nov 1999 14:48:42 -0700 From: Andrew Hunter Subject: flowbench I just thought that if you wired in multiple injectors, the software would fire them like a batch fire system. On the downside, you couldn't use a flow meter with the unit. > >Date: Fri, 19 Nov 1999 11:53:09 -0600 >From: steve ravet >Subject: flowbench > >Off the top of my head, you'd need a driver circuit for each injector, >and you'd have to modify the software (if you used it) to drive more >than one at a time. I think it used the parallel port to control the >driver circuit. > >- --steve >------------------------------ ------------------------------ Date: Fri, 19 Nov 1999 18:40:07 -0500 From: Darren Floen Subject: Speed sensor Hi everyone.A while back i was asking questions about fuel injection for a 4.3,being swapped into a Toyota.Well,i have now found a newer engine to use.I picked up a 91 4.3 throttle body engine,from a Safari van. So now i need a wiring harness.I contacted Howell and Painless.Howell says a speed sensor is not required for the engine to run smoothly.Matt at Howell says that it will only affect the EGR,and not the IAC. Painless says that the engine will always be stalling on deceleration. My question is this.How will the IAC motor reset its position if it doesn't have a speed sensor input?It is my understanding that this happens when the vehicle reaches 30 MPH. There is no smog testing where i live. So,do i need a speed sensor or not? Anyone know of any good websites dealing with 4.3 swaps and such? Thanks, Darren Floen Thunderbay,Ontario ------------------------------ Date: Fri, 19 Nov 1999 19:04:41 -0500 From: "Bruce Plecan" Subject: Re: Speed sensor If it wasn't needed, why did gm even bother?. If you do everything right, then there are no errors. Again, I'm not impressed with Howell, amongst others. I'll take reading the archives here, and seeing what the guys who truely know code have to say about things. It's alot easier to do it right once, then rehash twice. Just consider your 4.3 as a 5.7 with 2 cylinders missing, all the sensors are the same, and your probably running a 1227747 ecm, right?. As far as efi swapping it's a matter of getting a good wiring diagram and getting real comfortable, and go wire by wire. Mechanically don't overlook, or minimize the importantance of Subject: Re: Spark retard for EEC-V (DIS) Hi David, Picking off the crank signals and using them for accurate spark control is easier than you think. The 10 degrees resolution is actually not a hindrance. Once the engine starts cranking your first goal is to determine TDC of Cyl. 1. You find this by counting how long it takes to go from tooth to tooth and comparing that to the last time. In PIC assembler you can do this easily by setting up the timer and counting how many times it rolls over from a initial value. At 6600RPM each tooth will take about 250uSec so you have to factor your timer resolution to have a reasonable count at that RPM. At cranking you've got almost forever in PIC cycles. Once you find the TDC each successive tooth gives you a 10 degree interval that translates into engine RPM. Count each one and when you reach 18 you know you are at BDC. Actually, if you set your divisor correctly and assume RPM stays fairly constant over a 180 degree stroke you can use these timer ticks to determine when to fire the spark plug.(4 cyl engine). For example: for an 8cyl engine you fire every 90 crank degrees. This is 9 teeth. At tooth #4 set a variable that matches what the count should be at your desired ignition point; turn on current to the coil(Dwell period). When the count matches, fire the plugs by removing current through the coils (waste spark). Fire them again at tooth 9, 18, 27 and 35( + tooth gap) just in case you missed the previous count. If you don't get engine RPM after your timer as overflowed a few times then the engine has stopped. Shut off the current to the coil in case it's still on to avoid burning out the coil. Hope this makes sense. I even added knock detect and retard by using a knock sensor and using an input into the PIC to change what constant was added to the delay. This retarded the ignition to avoid knock. John Dammeyer > >Date: Fri, 19 Nov 1999 07:41:14 -0500 >From: "Posea, David G, SITS" >Subject: Spark retard for EEC-V (DIS) > >has anyone thought about building a programmable retard unit for a DIS >ignition. Hopefully one with boost retard built in. I've started developing >some PIC code, but I'm not an electronics type. There seems to be two ways >to go. One is to intercept the crank trigger. It has 35 teeth and one >missing one, for a pulse every 10 degrees. That makes writing the retard >code a little tricky, as more than 10 degrees of retard would span pulses. >The other way is to use the coil triggers as inputs. I'm not sure if 4 >identical chips should be used, or if one chip should process all inputs. >Does anyone have any ideas on which way I should go. I'm a programmer by >trade, and the PIC assembly language is pretty easy to work with. Any help >you can offer will be greatly appreciated. > > >David Posea > ------------------------------ Date: Sat, 20 Nov 1999 00:58:42 -0500 From: "Posea, David G, SITS" Subject: Spark retard continued Thanks Martin and Jon for the replies. I've checked out the PIC'N'POKE page, and a few other web resources. One degree of delay is equal to: 60 / (RPM * 360) seconds and RPM = 60 / time between pulses These two simple equations can be scaled in millisecs or uSecs for ease in working with a PIC controller. But I keep getting lost in the interrupts for processing 4 inputs triggered by a falling edge. One cycle is the time between falling edges for one input. Do you think I should zero out TMR0 at the start of input #1, then use TMR0 to track the time. I.E. Input #1 time = TMRO at interrupt, Input #2 time = TMR0 at interrupt - Input #1, etc. ?? There has to be a better way of doing that :) Thanks, David - -----Original Message----- From: DIY_EFI-Digest-Owner@xxx.edu [mailto:DIY_EFI-Digest-Owner@xxx.edu] Sent: Friday, November 19, 1999 15:00 To: DIY_EFI-Digest@xxx.edu Subject: DIY_EFI Digest V4 #650 DIY_EFI Digest Friday, November 19 1999 Volume 04 : Number 650 In this issue: Spark retard for EEC-V (DIS) flowbench See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. - ---------------------------------------------------------------------- Date: Fri, 19 Nov 1999 07:41:14 -0500 From: "Posea, David G, SITS" Subject: Spark retard for EEC-V (DIS) has anyone thought about building a programmable retard unit for a DIS ignition. Hopefully one with boost retard built in. I've started developing some PIC code, but I'm not an electronics type. There seems to be two ways to go. One is to intercept the crank trigger. It has 35 teeth and one missing one, for a pulse every 10 degrees. That makes writing the retard code a little tricky, as more than 10 degrees of retard would span pulses. The other way is to use the coil triggers as inputs. I'm not sure if 4 identical chips should be used, or if one chip should process all inputs. Does anyone have any ideas on which way I should go. I'm a programmer by trade, and the PIC assembly language is pretty easy to work with. Any help you can offer will be greatly appreciated. David Posea - ------------------------------ Date: Fri, 19 Nov 1999 11:53:09 -0600 From: steve ravet Subject: flowbench Off the top of my head, you'd need a driver circuit for each injector, and you'd have to modify the software (if you used it) to drive more than one at a time. I think it used the parallel port to control the driver circuit. - - --steve > Date: Thu, 18 Nov 1999 13:54:27 -0700 > From: Andrew Hunter > Subject: Fuel Injector Flowbench > > For those of you in the know, would it be possible to run muliple injectors > on the Perfomance Engineering Flowbench? > > Thanks, > Andrew > - - --steve - - -- Steve Ravet steve.ravet@xxx.com Advanced Risc Machines, Inc. www.arm.com - ------------------------------ End of DIY_EFI Digest V4 #650 ***************************** 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". ------------------------------ End of DIY_EFI Digest V4 #651 ***************************** To subscribe to DIY_EFI-Digest, send the command: subscribe diy_efi-digest in the body of a message to "Majordomo@xxx. 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