DIY_EFI Digest Thursday, 29 August 1996 Volume 01 : Number 252 In this issue: Re: switching between EPROMS Sparkplug Mounted Ignition Coils Re: switching between EPROMS Re: switching between EPROMS Re: Sparkplug Mounted Ignition Coils Re: real time dyno Re: switching between EPROMS Re: switching between EPROMS Re: Bosch MAF to Hitachi MAF Re: Newer VATS Vehicles See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "John Faubion" Date: Wed, 28 Aug 1996 20:03:34 -0500 Subject: Re: switching between EPROMS > You could also buy a ROM simulator, and just change the needed values. I > have the DATAMAN S3, and it is a bit overkill, but you can plug it into a > byte wide rom socket, and change blocks of memory if needed. You could also > get a low cost plug in simulator, and use a laptop to change much of what > you need. Sandy since you mentioned this, do you (or anyone else for that matter) know of a ROM simulator for the 27512 or 27C512 ROM? Maybe something to run off a serial or parallel port? It looks to me like this would be the easiest way to hack the code on the GM ECM. John Faubion jfaubion@xxx.net ------------------------------ From: Darren McInnes Date: Thu, 29 Aug 1996 12:14:34 +1000 Subject: Sparkplug Mounted Ignition Coils Hi Everyone, I've been looking for a supplier of Spark coils that mount on top of the Sparkplug for my EFI project. The only supplier i have found in australia wants $500(AUS) per coil and has no data available on them. Any assistance appreciated. Darren McInnes Archer Technologies P/L Toyota Celica SX 1989 3S-GE Engine ------------------------------ From: Sandy Date: Wed, 28 Aug 1996 20:46:44 -0700 Subject: Re: switching between EPROMS [snip] >Or even better is the Unirom, by Tech Tools, it will allow code changes >on the fly. I've also got a Dataman, but S4 not S3, and it's a great >tool, but to make changes, you need to shut the engine down. > >Todd Knighton >Protomotive Engineering Oops, I have the S4 too, Its been too long since I have used it... Where is Protomotive Engineering anyways. Sandy ------------------------------ From: Sandy Date: Wed, 28 Aug 1996 21:05:17 -0700 Subject: Re: switching between EPROMS Here is a list of ROM simulators from the back of Embedded Systems Engineering, and the Circuit Cellar, check out some of the other trade rags, they will have em' too! RomEm From MSD (Not the ignition guys) from $395-995 (408) 296-4000 Dataman S4 - Programmer and Simulator $795 (800) 328-2336 PROMJet from EmuTec $249 (206) 337-0857 flexROM from TechTools $149+ (214) 272-9392 E4 Emulator from SDI $249 (800) 352-9770 One thing to check is that some plug the unit directly into the socket, while some have a short ribbon connector. Try thg last two, the prices and features can be adjusted to you budget. Sandy ------------------------------ From: Sandy Date: Wed, 28 Aug 1996 21:07:42 -0700 Subject: Re: Sparkplug Mounted Ignition Coils Chevy will have something like that (coil per plug) on the new Corvette motor, look in any of the car mags for a picture. I'm don't know much more then that. I think that SAAB may also do the same. Sandy ------------------------------ From: "John Faubion" Date: Wed, 28 Aug 1996 23:05:11 -0500 Subject: Re: real time dyno > I have been trying to work out how to mount some sort of speed sensor on the > front wheel. It is difficult as it uses spoked motorcycle front wheels in an > open wheel format. So there is no front brake and hence no backing plate to > mount things on, just a rear hand brake and a parachute! > > One other thing, which we don't have a problem with at the moment but is kept > in mind, is that the front wheels can be prone to lifting off the ground and > hence losing the rotational information. The only other way I know of is to use a fifth wheel. RacePak has a system that uses a small aluminum hub with a solid rubber tire of about 5-6 inches in diameter. This is designed to be mounted off the rear axle housing and it has a spring load mechanism to keep it in constant contact with the ground. I remember a while back there were several people saying that a wheel this small wouldn't work due to the high frequency required to monitor it but I know this system is designed for professional drag racers and is used on Kenny Bernsteins top fueler running over 300 MPH! Let see at 300 MPH, that's 300/3600x5280 = 440 feet/sec. A 6 inch wheel covers 6xPI/12 = 1.57 feet. So our input frequency from a single magnet or even an optical sensor mounted to it, would be 440/1.57 = 280 Hz. I'm not sure but I think if we tripled the number of magnets we could still handle the frequency without problems and you would get a resolution of about a half foot on the track for about 2500 samples per quarter mile. No this wouldn't work on public roads but it should work on a drag strip. John Faubion jfaubion@xxx.net ------------------------------ From: Land Shark Date: Wed, 28 Aug 1996 22:21:49 -0600 Subject: Re: switching between EPROMS At 17:47 8/28/96 -0700, you wrote: >Or even better is the Unirom, by Tech Tools, it will allow code changes >on the fly. I've also got a Dataman, but S4 not S3, and it's a great >tool, but to make changes, you need to shut the engine down. Agreed .. (I'm one of the UNIROM's biggest fans ;) Jim C. ------------------------------ From: Darrell Norquay Date: Wed, 28 Aug 1996 21:26:26 -0700 (PDT) Subject: Re: switching between EPROMS At 09:06 PM 8/28/96 +1200, Warren Crowther wrote: >I'd prefer to do it with the engine ON!!! I don't see any reason why it >cannot be done, provided the switch over is not done at a critical time, and >that the only difference between the EPROMS is the data: ie. the fuelling, >ignition timing, etc. Also it should be done quick enough so that the micro >does not miss an external data fetch (anyone know what the micro will do in >this case?? will it hang or retry? ). > >Warren This probably will not work. You COULD build in some logic that waits until both the CS (chip select) and OE (output enable or read line) are inactive, then switch them over to the other chip. BUT, if you do this, what's to say that the other chip will have exactly the same code in the same place? (if it does, what's the point of switching?) The processor may be in the process of executing some instruction when you do the switch, and the new EPROM may have completely different insructions at the same address. The processor then executes a JTZ instruction, (Jump to Twilight Zone) and you're baked. Same applies if the EPROM isn't enabled or finished putting data on the bus by the time the processor reads it. There are two ways this might work: (1) If the actual running code is identical in both chips, and you only modified the values in, say, the fuel map, and haven't added or subtracted any code, this method MAY work. Your added circuitry would be fairly complex, and must be both synchronized to the processor clock and fast enough to complete the switch between bus read cycles. Timing would be critical in this scenario. (2) If your circuitry did a hardware reset after switching the CS and OE to the new chip, you may get away with it, if the car will run long enough to survive a cold reboot of the ECM. If the micro copies the data from the EPROM into RAM when it boots (say, for use in some adaptive algorithm), changes in the RAM table would occur while the engine was running. It would require a hard reset to recopy the new data from the new EPROM into the RAM map. Also, you'd have to make sure you check the EPROM checksum (if it has one), and fudge in some data to make the checksum the same for both chips. regards dn dnorquay@xxx.com ------------------------------ From: Darrell Norquay Date: Wed, 28 Aug 1996 21:26:32 -0700 (PDT) Subject: Re: Bosch MAF to Hitachi MAF At 02:27 PM 8/28/96 CDT, Terry Mclane wrote: > Is there an easy way to invert the voltage signal from the Hitachi to > the ECU? A single opamp would do the trick. Use a rail-to-rail output device designed for single supply operation, and power it off the same 5V supply as the MAF. Set the opamp up in an inverting unity gain buffer configuration, and the output signal will be the exact opposite of the input. The IC Opamp Cookbook by Walter Jung, pub by Howard W Sams & Co is a good reference. Also, the National Semiconductor Linear Applications Handbook has the same information. > Is there any way to also adjust the low/hi voltage signals, and > interpolate between them? If I could get the voltage of both units at > a set of RPM (idle, max torque), it would be nice to get a smooth > interpolation. I'm not sure what you're up to here. Do you want to run both units at the same time, or what? regards dn dnorquay@xxx.com ------------------------------ From: Darrell Norquay Date: Wed, 28 Aug 1996 21:26:30 -0700 (PDT) Subject: Re: Newer VATS Vehicles At 09:29 AM 8/28/96 -0600, Wayne Braun wrote: > I donm't know about vettes, but I recently watched a program on A&E >about stolen vehicles. The year that GM started putting the VATS stuff into >the camero/firebird theft dropped something like 75%. This same program >re-stated a couple of things; What about the next year, after the thieves figured out how to get around it? After all, if guys on the list can do it, so can anyone with enough technical knowledge. regards dn dnorquay@xxx.com ------------------------------ End of DIY_EFI Digest V1 #252 ***************************** 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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