DIY_EFI Digest Thursday, January 20 2000 Volume 05 : Number 031 In this issue: Knock [ADMIN] Lists are moving! Re: [ADMIN] Lists are moving! Minimum to run GMECM? Need an ECM Re: Minimum to run GMECM? Minimum to run GMECM Re: DIY_EFI Digest V5 #28 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 11:47:21 +1300 From: Simon Quested Subject: Knock > From: "Robert W. Hughes" > Actually, the exhaust gases dilute the mixture and make the combustion > temperatures lower. How do you add hot and get cold? I'm confused.... > From: "Scott Croughwell" > > How does the hot exhaust gas cool the fresh charge.... Or have I got this > > wrong and you mean that the exhaust gas isn't heating the cool intake charge > > and the cold intake charge is causing the detonation???? > > Believe it or not... the gasses coming from the EGR have had enough time to cool > enough so that the portion of exhaust temp re-entering the intake port is cooler > than the intake manifold. Wow so the exhaust gas is cooler than the intake I never would have thought so.... hell I'm not even running emmissions gear, don't have to here in NZ. It is even legal to remove cats.... ------------------------------ Date: Wed, 19 Jan 2000 16:01:01 -0800 (PST) From: Orin Eman Subject: [ADMIN] Lists are moving! Hopefully, the move will start tomorrow, 5pm EST. There will almost certainly be a disruption/delay in service around that time, so please refrain from posting tomorrow (Jan 20th) afternoon until further notice. Orin. ------------------------------ Date: Wed, 19 Jan 2000 19:10:19 -0500 From: "Bruce Plecan" Subject: Re: [ADMIN] Lists are moving! DTs are already setting in <>... Grumpy | Hopefully, the move will start tomorrow, 5pm EST. | There will almost certainly be a disruption/delay | in service around that time, so please refrain from | posting tomorrow (Jan 20th) afternoon until further notice. | | Orin. | ------------------------------ Date: Wed, 19 Jan 2000 19:13:50 -0500 From: "jtyler" Subject: Minimum to run GMECM? For a basic DIS MAP application what are the minimum inputs that a GMECM is going to need to run? 1)Obviously power,ground, ignition 2)the connections to the DIS which I believe will supply RPM via the crank sensor, other misc power and ground connections. 3) MAP 4) Injector connections 5) TPS? I assume the unit would at least idle without this hooked up? 6) temp? same thing? 7) VSS ? can this be fooled or bypassed since I have no sensor in this application 8) knock? I assmume not required just to make it idle 9) others required? Basically, I am trying to figure out what is the minimum to crank and run angine with a 1227165, 748,749 or 730 and DIS. Since I won't have a complete GM vehicle to tinker with, I will get as much as I can from some donor vehicle. Thanks! Jim ------------------------------ Date: Wed, 19 Jan 2000 19:20:12 -0500 From: "jtyler" Subject: Need an ECM Anyone out there have a 1227165, 748,749 or 730 that you want to sell? >From a 4cyl DIS app would be best, but not required. It could be dead (as a core) or fully functional. If you have 4cyl DIS stuff to go along with it I could buy that as well. Thanks very much, Jim ------------------------------ Date: Wed, 19 Jan 2000 19:32:13 -0500 From: "Bruce Plecan" Subject: Re: Minimum to run GMECM? Lets see, from the nature of this question, I'd almost quess that you have a limited amount of efi experience. So you with this limited background want to jump in and redesign what gm has spent millions of dollars on, and install it some other way. OK.. 2nd, leaving all/most/some of the sensors disconnected negates any benefits to running efi, might as install a carb.. Least you might have something that is proper to drive. The archives here and at GMECM have lots of leads on how to do things. Grumpy | For a basic DIS MAP application what are the minimum inputs | that a GMECM is going to need to run? | 1)Obviously power,ground, ignition | 2)the connections to the DIS which I believe will supply RPM | via the crank sensor, other misc power and ground connections. | 3) MAP | 4) Injector connections | 5) TPS? I assume the unit would at least idle without this hooked up? | 6) temp? same thing? | 7) VSS ? can this be fooled or bypassed since I have no sensor in this | application | 8) knock? I assmume not required just to make it idle | 9) others required? | Basically, I am trying to figure out what is the minimum to crank and | run angine with a 1227165, 748,749 or 730 and DIS. Since I won't have a | complete GM vehicle to tinker with, I will get as much as I can from some donor vehicle. | Thanks! | Jim | ------------------------------ Date: Wed, 19 Jan 2000 19:37:49 -0500 From: "jtyler" Subject: Minimum to run GMECM I just found Bruces Test bench article. It answered many of the questions. Any other words of wisdom would be appreciated! Jim ------------------------------ Date: Wed, 19 Jan 2000 20:31:46 -0800 From: "Steve" Subject: Re: DIY_EFI Digest V5 #28 > > Date: Tue, 18 Jan 2000 11:57:04 -0800 > From: "Scott Croughwell" > Subject: Re: DIY_EFI Digest V5 #27 > > > How does the hot exhaust gas cool the fresh charge.... Or have I got this > > wrong and you mean that the exhaust gas isn't heating the cool intake > > charge and the cold intake charge is causing the detonation???? > > Believe it or not... the gasses coming from the EGR have had enough time to > cool enough so that the portion of exhaust temp re-entering the intake port > is cooler than the intake manifold. (Thus, EGR valve only opens when the > engine is at "operating temperature".) But if engine knock is only apparent > at something other than high engine loads and/or speeds... I'd be willing to > bet dimes to dollars it's due to the EGR being disconnected or inoperable. Well, I have put a thermocouple in the intake manifold and can state the results of what I found. With the EGR not operating and using a cold air intake I was seeing around 125F after the throttle body on a turbocharged and intercooled V6 at light cruise conditions. With EGR operational, as soon as the valve opened under the same conditions the intake manifold temp jumped to 210F on a 75F day. I think that it is less a temperature issue than a charge dilution issue. But with some fine tuning of the spark map, you can easily eliminate any detonation you may experience. YMMV Steve ------------------------------ End of DIY_EFI Digest V5 #31 **************************** 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".