DIY_EFI Digest Friday, January 21 2000 Volume 05 : Number 034 In this issue: [admin] test 2 Knock [ADMIN] The Move Believe it or not... NOT re:Minimum to run GMECM? re:Minimum to run GMECM? Re: Believe it or not... NOT re: Minimum to run GMECM? See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Thu, 20 Jan 2000 19:50:44 -0500 From: jsg@xxx.com Subject: [admin] test 2 - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Fri, 21 Jan 2000 14:16:16 +1300 From: Simon Quested Subject: Knock > This is what I was saying. The exhaust gases dilute the mixture and and > result in cooler combustion chamber temperatures Ok.... so the inlet manifold temp goes up but the mixture is diluted by the exhaust gas from the erg. I would have thought that this would have leaned the AFR if anything causing detonation or isn't there enough O2 left in the exhaust? >> hell I'm not even running emmissions gear, don't have to here in NZ. It > > is even legal to remove cats.... > How about dogs? sorry So you should be =-) - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Thu, 20 Jan 2000 17:22:26 -0800 (PST) From: Orin Subject: [ADMIN] The Move This lists are currently running off the new server. You might have noticed your filters not working anymore. You will have to change references to esl.eng.ohio-state.edu or efi332.eng.ohio-state.edu to diy-efi.org in your filters, aliases and address books. The new address for subscribe/unsubscribe requests is: majordomo@xxx.org We even have an annoying reminder at the bottom of each message at the moment :). If you are on diy_efi-digest, please refrain from switching to diy_efi for a day or two while we make sure everything is running smoothly. Thanks, Your list admins. - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Thu, 20 Jan 2000 02:09:18 +1100 From: Phil Lamovie Subject: Believe it or not... NOT How does the hot exhaust gas cool the fresh charge.... is a good question. Unfortunately it's not the right one. How does the introduction of exhaust gas lower the temperature of combustion is a better one. Keep in mind that the engine is a sequence of discrete events. The combustion temp is lower beacause there is less fuel burned and this is achieved by first using exhaust re-entry to help raise the compression. As the exhaust is 70% nitrogen and nearly 30% CO2 it is very nearly inert gas. Adding this gas without any change in throttle position increases the relative compression ratio. The raised compression allows the engine mapper to lower the amount of fuel i.e. increase the A/F ratio to a greater number prior to the onset of unstable combustion. The Exhaust gas is NOT suddenly cooled. your in the pursuit... phil - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Thu, 20 Jan 2000 21:35:48 -0500 From: "jtyler" Subject: re:Minimum to run GMECM? No I wasn't getting pissy. Thank you for all your help already. I really meant it just seems for the relatively simple app I described, trying to disable/fool/recode 80% of the ECM provisions may not be the way to go. SDS or similar may be smarter if it is going to take 2 years to figure out how too undo all that GM spent millions doing. With all the provisions in the GM code (and I realize why they have to do that stuff), it seems like trying to use a sledgehammer to drive a nail. All the complexity GM had to do for a production vehicle simply isn't neccesary for my application. I was trying to find more info on the 168/808 applications you mentioned. I haven't found if any of those where DIS. I could use a speedo cable VSS if the ECM is going to get dumb without it. So: VSS,MAP,Temp,TPS,Ignition maybe that would be enough. I looked at the 165 app on TC, it was a MAF. The 227 app there had a 4 cyl switch and was MAP, but was auto, so I'll look for the manual version. >Perhaps this application is just too basic for all that GM wizardry... >sorry I bothered you with it. >Jim - ------------------------------ >Date: Thu, 20 Jan 2000 17:27:08 -0500 >From: "Bruce Plecan" >Subject: Re: re:Minimum to run GMECM? THESE ARE ALL OUTPUTS!!!!. If you want to get/or seemingly pissy, fine, I'll withdraw my efforts to answer your questions. Grumpy - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Thu, 20 Jan 2000 23:40:32 -0500 From: "Mike Pitts" Subject: re:Minimum to run GMECM? In a generic sense, I would think the following are minimum. +12V and Ground...duh ;-) MAP or MAF depending on ECU type TPS Coolant Temp Air Temp Tach signal O2 sensor <- don't skimp on this! Maybe a cam sensor Some controls (like EGR) have circuitry in them which is used by the ECU to detect their existance and proper operation. Without some of these controls, you would probably get several error codes, which may put the ECU in a limp or semi-limp mode. I would definately hook up the SES lamp and have a tool like Diacom available. For the VSS, if the ECU thinks the trans is in gear and sees an RPM of say >3000 for example, it may flag a VSS error code. VSS affects the engine control in some models more than others. If you could just get any kind of decent pulse to the ECU when the vehicle is moving, that would probably be enough for it to determine coasting vs stopped. If it were me, I'd grab everything I could off the donor car, especially the harness. And try to put it all into use, except for the cannister purge and EGR (yeck!). JMO Good luck, - -Mike - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Thu, 20 Jan 2000 23:55:06 -0500 From: "Bruce Plecan" Subject: Re: Believe it or not... NOT This doesn't make sense to me. Static CR would remain the same. The dynamic/effective CR should still be the same since nothing none compressable was added to the mix. The VE should drop (less O2 to react), hence lower fuel amount needed, leaner mixture takes longer to burn hence more timing needed. Grumpy | As the exhaust is 70% nitrogen and nearly 30% CO2 it is very nearly | inert gas. Adding this gas without any change in throttle position | increases the relative compression ratio. | The raised compression allows the engine mapper to | lower the amount of fuel i.e. increase the A/F ratio to a greater | number prior to the onset of unstable combustion. - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ Date: Fri, 21 Jan 2000 04:09:10 -0600 (CST) From: "Gregory A. Parmer" Subject: re: Minimum to run GMECM? > I only need one Idle speed after warm up. Try it without VSS. I did. You'll find that you need a VSS signal for the IAC to reset and give the a proper idle speed. I s'pose you could plug the IAC port totally, but it sure is nice to have fast idle while cold, etc. - -greg (maybe I'll just add that to my .sig file...) - ---------------------------------------------------------------------------- To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes) in the body of a message (not the subject) to majordomo@xxx.org ------------------------------ End of DIY_EFI Digest V5 #34 **************************** 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".