DIY_EFI Digest Monday, November 1 1999 Volume 04 : Number 615 In this issue: Re: DIY_EFI Digest V4 #614 See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Sun, 31 Oct 1999 19:20:26 -0500 From: Rick Ricker Subject: Re: DIY_EFI Digest V4 #614 looks super! DIY_EFI Digest wrote: > DIY_EFI Digest Sunday, October 31 1999 Volume 04 : Number 614 > > In this issue: > > Re: DIY_EFI Digest V4 #613 > Limp home mode on GM systems > Dallas 80C550 > Re: DIY_EFI Digest V4 #613....AE Transients > > See the end of the digest for information on subscribing to the > DIY_EFI or DIY_EFI-Digest mailing lists. > > ---------------------------------------------------------------------- > > Date: Sun, 31 Oct 1999 08:23:28 -0600 > From: nacelp@xxx.com (CSH-HQ) > Subject: Re: DIY_EFI Digest V4 #613 > > Just hook it all up per the factory. The "tough"part is the VSS and just > read the archives for that. > All the sensors?. TPS, CTS, VSS, MAP, how much simplier do you want?. > The ecm powers the fuel pump for about 2 sec when you turn the key on to > prime the system, from then on it's the oil pressure switch that powers it. > In a roll over it serves as a saftey item, since inverted there is no oil > pressure. > Don't try just running in limp home mode, or just start it that way, do it > right once, and limp home mode will probably get ya home if needed. > Grumpy > > > > >From: Mike Comai > >Subject: Limp home mode on GM systems > >I'm putting a GM '747 system into a 1979 CJ5. I was curious if anyone new > >what sensors/systems the ECM uses when it enters limp home mode. I > >noticed that on the schematics it looks like the fuel pump is running all > >the time when the oil pressure switch is closed(i.e. bypasses the relay) > >and the only reason I can think for that would be if the ECM fails or > >enters L.H.M., or the relay fails. I just wanted to make sure that I > >think of all the angles when I do the install, and I'd appreciate any > >more info on L.H.M. or any other odities that aren't easy to see. Thanks, > >Mike Comai > > ------------------------------ > > Date: Sun, 31 Oct 1999 09:40:13 -0800 > From: "John Dammeyer" > Subject: Limp home mode on GM systems > > Hi, > > First I guess we have to decide what consitutes LHM. For instance, my water > temperature gauge input is used to determine when the engine is warm enough to > remove cold start enhancement. At 150 degrees all enhancements are gone and up > to 150, the difference in engine temperature and 150 is used as a gain > enrichment factor. If the gauge fails open it reports 240 degrees so I force it > to read 220 and remove enrichment. If it fails short or stops responding I do > nothing. I should probably add some sort of warmup timer that sets the > temperature to +150 if the temperature sender hasn't changed. > > If the MAT fails open it reports -60 so the mixture is rich. I haven't tried > the engine at -40 in winter so I do not know if I should consider -60 a problem. > In either case, if it does fail this way, it just enriches the mixture. Not a > real problem. > > TPS is only used for acceleration and WOT enrichment so if it fails the engine > stumbles under acceleration but does run. > > O2 sensor only impacts the mixture a little bit so can be discarded if it fails. > ie: if it reports the wrong values the engine just runs a tinly bit rich or lean > but still runs fairly well. > > MAP sensor This is the biggy. If it fails such that it reports low pressure > the mixture will be lean and the engine will have a major drivability problem. > If it fails with a high pressure reading the mixture will be excessively rich. > In all cases when the MAP sensor is disconnected, the engine stalls. > > The Barometer sensor is also somewhat critical if it fails with a low pressure > reading as the mixture will become very lean. A failure with a high pressure > reading defaults to just below sea level (Amsterdam?) so becomes unimportant > other than enrichening the mixture somewhat. > > I currently do not sense if the injectors are functioning or what the CD > capacitor voltage is so I can't determine a LHM from that. If the RPM sensors > fail, so does the timing and therefore so does the engine. Fuel Pump is > determined from presense of pulses and I wouldn't subvert that because of fire > hazzard if the ECU thinks LHM is there when vehicle has crashed. > > Cheers, > John Dammeyer > > >Date: Sat, 30 Oct 1999 22:09:58 -0500 (EST) > >From: Mike Comai > >Subject: Limp home mode on GM systems > > > >I'm putting a GM '747 system into a 1979 CJ5. I was curious if anyone new > >what sensors/systems the ECM uses when it enters limp home mode. I > >noticed that on the schematics it looks like the fuel pump is running all > >the time when the oil pressure switch is closed(i.e. bypasses the relay) > >and the only reason I can think for that would be if the ECM fails or > >enters L.H.M., or the relay fails. I just wanted to make sure that I > >think of all the angles when I do the install, and I'd appreciate any > >more info on L.H.M. or any other odities that aren't easy to see. Thanks, > > > > ------------------------------ > > Date: Sun, 31 Oct 1999 09:22:23 -0800 > From: "John Dammeyer" > Subject: Dallas 80C550 > > Hi Nick, > > I've struggled with this one too. What I currently do is increase the pulse > width to a maximum value of 13ms for n seconds. I determine this from a change > in throttle position (dTPS) where the amount of change above a minimum change is > multiplied by a gain factor and then added to the current pulse width. > > If the TPS goes above a certain value like 75% then I just apply a richer > mixture (11:1). > > The tests are done with a large multi-bladed fan on a 2.4:1 reduction belt drive > so the load on the engine varies with the fan speed. From idle to WOT I get a > stumble that I haven't been able to get rid of yet. From 3500RPM to WOT the > engine just quickly increases speed to 5100RPM. The Fan loads the engine such > that the engines maximum speed is at the peak torque value which for a propellor > is just perfect. > > Can you tell me how you are doing the timing for the sequential injection? ie: > at idle where are you starting/ ending the injection pulse and where at max > power? How are you determining RPM? I'm using the 80C592 and 95% of the code > is in Tasking C. > > Regards, > > John > > >Date: Sun, 31 Oct 1999 11:40:06 +1300 > >From: "Nicholas Parker" > >Subject: Re: DIY_EFI Digest V4 #611 > > > >Hi List, > > > >I have written an ecu in assembler for 80c552, but I now have a Dallas > >80c550 (8x faster or so). Its for a 4 cyl, two coil, sequential injection > >etc. I haven't implemented 'acceleration enrichment' yet. Can somebody > >please give me some guidelines, ie: The car I designed the ecu for is a > >supercharged Toyota MR2 mk1. so It kind of operates in both modes...that is > >both forced induction, and natural aspiration bue to an electromagnetic > >supercharger clutch, and a supercharger bypass. > > > >Thanks, Nick Parker. > > > > ------------------------------ > > Date: Sun, 31 Oct 1999 14:26:49 EST > From: EFISYSTEMS@xxx.com > Subject: Re: DIY_EFI Digest V4 #613....AE Transients > > Hi, > You didn't state whether this is speed density or MAF....Man, there is > no quick and dirty "good" way to do AE......It's a pretty good example of > what to do, look at the Gm stuff as shown on the ftp site or ecm guys > hacks....you'll have to stroll down through the code to find the AE stuff but > is usually all in one spot....also watch for the IAT(Intake Air Temp) > equation also....sorry for the vagueness but AE is alot tougher than steady > state.....hth's > - -Carl Summers > > In a message dated 10/31/99 2:19:50 AM Pacific Standard Time, > DIY_EFI-Digest-Owner@xxx.edu writes: > > << > Date: Sun, 31 Oct 1999 11:40:06 +1300 > From: "Nicholas Parker" > Subject: Re: DIY_EFI Digest V4 #611 > > Hi List, > > I have written an ecu in assembler for 80c552, but I now have a Dallas > 80c550 (8x faster or so). Its for a 4 cyl, two coil, sequential injection > etc. I haven't implemented 'acceleration enrichment' yet. Can somebody > please give me some guidelines, ie: The car I designed the ecu for is a > supercharged Toyota MR2 mk1. so It kind of operates in both modes...that is > both forced induction, and natural aspiration bue to an electromagnetic > supercharger clutch, and a supercharger bypass. > > Thanks, Nick Parker. > > ------------------------------ > >> > > ------------------------------ > > End of DIY_EFI Digest V4 #614 > ***************************** > > 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 #615 ***************************** 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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