DIY_EFI Digest Monday, 22 April 1996 Volume 01 : Number 117 In this issue: MCS48 cross-assembler? Re: MAF bypass loop Re: MAF with bypass port Re: MCS48 cross-assembler? Re: MAF bypass loop Re: Ignition questions & the Nat semi Injector driver Re: MCS48 cross-assembler? See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: cmorris@xxx.com (Charles) Date: Sun, 21 Apr 1996 07:27:15 -0700 Subject: MCS48 cross-assembler? I'm in the process of building an additional injector controller, which uses an Intel 8748 microprocessor. Since hand-coding is a real PITA, does anyone know where I can find an assembler which runs on a PC? Thanks, - -Charles ------------------------------ From: "George M. Dailey" Date: Sun, 21 Apr 1996 10:43:35 -0500 Subject: Re: MAF bypass loop At 08:45 PM 4/20/96 -0600, you wrote: >Hello gang! > >I was wondering if anyone has seen/tried this type of MAF setup... > > >-----------------------------------------\ >from filter || MAF ---\ >---> ------------------------\ ---\ >--\ \________________________\ ----------------- > \ bypass line to engine ------> > \_______________________________________________________________ > >(sorry about the poor quality ASCII art, obviously I'm no expert!) > >The MAF is represented by the two vertical bars in the top tube. My >thought is this: the MAF is usually the most restrictive part of the >induction system, and who says it needs to be the only path to the engine. >I figure if you have a bypass tube sized so most of the flow doesn't see >the MAF at all, you will drastically reduce delta P trough the intake >tract. However, this is not without problems. I am not sure of the >Reynold's number range an MAF is designed to operate (anybody?). In >addition, I could see this type of setup reducing transient response of >the overall system. Whadda ya think? does this have potential? > >Getting back to the Reynolds # range; no doubt an MAF is fairly accurate >within a certain range and under specific conditions, how about below the >lower limit and above the upper limit? does the sensor response become >non-linear? is there even a response? will the sensor ouput curve flatten >off? What are the conditions an MAF is expected to operate? laminar >smooth, no turbulence? is there any rule of thumb re how far upstream you >must keep a straight shot to the sensor? Any help you pros could give me >would be greatly appreciated... > >Thanks gang. > >Todd- =========================================================================== Todd, the Japanese company Hitachi has been there and done that. Here is what I know about it. Some, not all, of GMs port fuel injected V6s used an Hitachi made MAF sensor like you described (sort of). The difference is, they placed the MAF element in the smaller BYPASS tube. My source gave two reasons for this. 1) As you mentioned, very low delta P accross the sensor. 2) Reduced trash fouling of the heated MAF element. Simply put, less total air passing by the sensor element. This reportedly eliminated the burn cycle that is so very needed on the Bosh hot wire MAF sensor. I discovered just how sensitive the Bosh unit was to trash when my TPI started surging with the air cleaner off. These same engines were also equiped with an Delco unit (most of the time I think). The Delco MAFS used a hot mylar film instead of the platnum wire and had no burn off cycle! I don't know why GM switched, unless the Delco was giving problems. I'd like to hear from an GM person on that. "... and that's all I have to say about that" GMD ------------------------------ From: Wayne Cox Date: Sun, 21 Apr 1996 13:21:53 -0400 Subject: Re: MAF with bypass port >The MAF is represented by the two vertical bars in the top tube. My >thought is this: the MAF is usually the most restrictive part of the >induction system, and who says it needs to be the only path to the engine. >I figure if you have a bypass tube sized so most of the flow doesn't see >the MAF at all, you will drastically reduce delta P trough the intake The hot-wire MAF in my Nissan SE-R is built this way. Not sure how many NIssans have this setup, or what their design goal was. It still looks awfully restrictive. The main passage through it is about 50mm, while the TB is 65 or so. -Wayne ------------------------------ From: Chuck Mancuso Date: Sun, 21 Apr 1996 16:37:04 -0700 Subject: Re: MCS48 cross-assembler? At 07:27 4/21/96 -0700, you wrote: > > >I'm in the process of building an additional injector controller, which >uses an Intel 8748 microprocessor. Since hand-coding is a real PITA, >does anyone know where I can find an assembler which runs on a PC? > >Thanks, >-Charles > > > I use a shareware assembler called TASM for the 8048. It works fine. My copy is quite old. I don't kmow if they're still around, haven't seen an ad for a while. Below is a copy of the readme file. /////////////////////////////////////////////////////////// TASM.EXE - TASM Assembler, executable TASM48.TAB - 8048 Instruction definition table TASM51.TAB - 8051 Instruction definition table TASM65.TAB - 6502 Instruction definition table TASM85.TAB - 8085 Instruction definition table TASM80.TAB - Z80 Instruction definition table TASM.DOC - TASM Documentation README - Brief Explanation of Disk contents COPYRIGH.T - Copyright notice ORDER.FRM - Order Form If you find TASM useful, why not register? For the $30.00 registration fee you get: 1. Latest version of TASM. 2. Source code (in C). 3. Bound Manual. To register, use the form on the last page of the manual, or just send $30.00 check or money order to: Speech Technology Incorporated 837 Front Street South Issaquah, WA 98027 //////////////////////////////////////////////////////////// Regards, Chuck Mancuso chuckm@xxx.com wmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwm || Chuck Mancuso || i i || || AEC Control Systems || {|} {|} || || Sandpoint, ID USA || {{|}} {{|}} || || chuckm@xxx.com || {((|))} {((|))} || || || {{{{|}}}} {{{{|}}}}|| || || ____|______________________|____|| wmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwmwm ------------------------------ From: MaxBoost@xxx.com Date: Sun, 21 Apr 1996 22:16:20 -0400 Subject: Re: MAF bypass loop >I was wondering if anyone has seen/tried this type of MAF setup... > > >-----------------------------------------\ >from filter || MAF ---\ >---> ------------------------\ ---\ >--\ \________________________\ ----------------- > \ bypass line to engine ------> > \_______________________________________________________________ > >(sorry about the poor quality ASCII art, obviously I'm no expert!) > >The MAF is represented by the two vertical bars in the top tube. My >thought is this: the MAF is usually the most restrictive part of the >induction system, and who says it needs to be the only path to the engine. >I figure if you have a bypass tube sized so most of the flow doesn't see >the MAF at all, you will drastically reduce delta P trough the intake >tract. Actually Jim Wolf Technology does something similar to this for the twin-turbo 300ZX. The stock setup uses one MAF for both banks. The JWT setup puts the MAF to the left bank/turbo only. This cuts down on the restriction. Obviously they re-map the eprom accordingly. Perhaps something similar could be done for a single inlet system by creating a fixed bypass and recalibrating around it. The stock sensor isn't a huge restriction at low hp levels, but more is always better.:) Max. ------------------------------ From: arthurok@xxx.com (ARTHUR OKUN ) Date: Sun, 21 Apr 1996 19:46:04 -0700 Subject: Re: Ignition questions & the Nat semi Injector driver put a capacitor "just jike a points circuit" accross the collector to emitter junction this is commonly done in tv sets to control the fly back collapse and to adjust picture with and high voltage "i guess an ignition coil is like an iron vs ferrite core flyback."ferrite is a form of iron"use agood mylar or plastic film 600vdc or better cap i think sometimes they put a small value resistor in series with the cap try starting with about a .25 uf cap for an eight cylnder engine then go up or down depending on the coil your using. ------------------------------ From: arthurok@xxx.com (ARTHUR OKUN ) Date: Sun, 21 Apr 1996 19:44:47 -0700 Subject: Re: MCS48 cross-assembler? You wrote: > > > >I'm in the process of building an additional injector controller, which >uses an Intel 8748 microprocessor. Since hand-coding is a real PITA, >does anyone know where I can find an assembler which runs on a PC? > >Thanks, >-Charles > >how about a FREE one circuit cellar 203 871-1988 ------------------------------ End of DIY_EFI Digest V1 #117 ***************************** 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".