DIY_EFI Digest Thursday, 11 September 1997 Volume 02 : Number 314 In this issue: O2 sensor output Rev limiter curcuit Re: Propane on Fuel Injected Cars RE: why is rich better for power ?? RE: CDI, accelerometer Re: Rev limiter curcuit SDS EFI RE: Fuel Injector Plug Insert Pins RE: ECU box locations Re: O2 sensor output RE: OBD II - fuel trims (adaptives) Re: O2 sensor loc re: SFI popping at wot Pulse Width meter schematic Re: Propane on Fuel Injected Cars Re: OBD II - fuel trims (adaptives) Re: Propane on Fuel Injected Cars See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "alex nicu" Date: Wed, 10 Sep 1997 04:22:03 PDT Subject: O2 sensor output Can anyone tell me what it's the output of an O2 sensor ( it's any diference between type ?) on perfect mixture ? Alex http://home.onestop.net/nalex ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com ------------------------------ From: Craig Pugsley Date: Wed, 10 Sep 1997 21:29:09 +1000 (EST) Subject: Rev limiter curcuit Here's my good deed for the day.. A few (5) years ago I designed & built a rev limiter that can be connected to any conventional kettering ignition (but has only ever been tested on a points ignition). It's based on an LM2917 and an SCR, which has the very nice side effect of being impossible to generate any mis-timed sparks, a highly desirable attribute for high output rotary engines (300+hp). When the limit is reached by _accelerating_ to the rev limit, the transition is smooth and causes no backfiring. (BUT it may well destroy the exhaust if the engine is downshifted and consequently over-revs) Please note that the description of the design philosophy and operation is not done yet (give me a few days for these) You can find it at: http://www.3rotor.com/rotary/PG01.HTM Also I have a design for a LED bargraph meter that displays injector % duty.. So I'll start drawing it up soon. Finally I may put up a new CDI design that's in a local electronics mag.. It's an impressive piece of work! Cheers, Craig. ------------------------------ From: clsnyde@xxx.net (Clare Snyder) Date: Wed, 10 Sep 1997 12:19:32 GMT Subject: Re: Propane on Fuel Injected Cars >Clare Snyder wrote: > >> Contact GFI Control Systems >> 100 Hollinger Cr >> Kitchener Ont. Canada >> (519)576-4270 >> >> They are, I believe, responsible for the Chrysler propane injection system, >> and are number one in that field. > >No, Chrysler developed it's own liquid phase propane fuel injection >system. GFI markets a suedo-vapour injection system which is more like >throttle body injection than multiport vapour injection. > >Neall > >-- >********************************** >Neall Booth >Bi-Phase Technologies >Development & Applications Engineer >nbooth@xxx.net >********************************** > The system is not TBI, I,ve seen it and it has multiple injectors. They have been working with FORD, were working with Chrysler, are partnered with Martin Marietta (not sure of spelling), apparently were doing some deisel work as well. What chrysler is using now may not be their system, but a couple years ago they were working together. There were dodge 4wd ambulances running with their system. ------------------------------ From: Tom Cloud Date: Wed, 10 Sep 1997 07:19:41 -0500 Subject: RE: why is rich better for power ?? >Tom, > There are a couple of reasons why richer is better if >it is power output you are interested in. Let me start with the [ snip ] > I hope this helps answer your question. > >Jim Boughton thanks, ------------------------------ From: John Hess Date: Fri, 29 Aug 1997 13:03:32 -0500 Subject: RE: CDI, accelerometer I hate to be a "me too"; but, there it is! > ---------- > From: > garfield@xxx.com] > Sent: Friday, August 29, 1997 10:22 AM > To: diy_efi@xxx.edu > Subject: Re: CDI, accelerometer > > On Fri, 29 Aug 1997 01:54:16 -0700 (PDT), "Robert D. McGhie" > wrote: > > >At 04:41 PM 8/28/97 +1000, Stuart wrote: > > >>Sept. 97 Silicon Chip magazine has a multiple spark discharge CDI > >>unit as a project. The kit is about A$100 from Dick Smith. > > >Could you post or email Dick Smith's address or how to contact him? > > POST IT!!!, since there are at least TWO of us that are interested!! > Gotta be several others lurking (this fact derived from the "Law of > Net > Lurking, which states that for every unlurked inquiry, there are at > least several others that wanted to know but were too > bashful/lazy/whatever to ask". 8) > > Garfield > ------------------------------ From: garfield@xxx.com (Garfield) Date: Wed, 10 Sep 1997 15:14:46 GMT Subject: Re: Rev limiter curcuit On Wed, 10 Sep 1997 21:29:09 +1000 (EST), Craig Pugsley wrote: >Here's my good deed for the day.. ......... >Also I have a design for a LED bargraph meter that displays injector % >duty.. So I'll start drawing it up soon. Cool. How soon? (hint hint) >Finally I may put up a new CDI >design that's in a local electronics mag.. It's an impressive piece of >work! Hey Craig. This is blinking excellent. You keep this up and I just may mention you in my will. 9) Garfield P.S. Is the CDI design you're thinking of the one in Silicon Chip? ------------------------------ From: John Hess Date: Fri, 5 Sep 1997 15:16:18 -0500 Subject: SDS EFI Someone on the newsgroup asked for the Internet address of SDS. Try http://www.sdsefi.com ------------------------------ From: John Hess Date: Mon, 8 Sep 1997 08:55:15 -0500 Subject: RE: Fuel Injector Plug Insert Pins Actual, the area code has changed. It is: Phone (248)362-1145 FAX (248)362-1032 > ---------- > From: Wilkrod@xxx.com] > Sent: Monday, September 08, 1997 7:53 AM > To: diy_efi@xxx.edu > Subject: Re: Fuel Injector Plug Insert Pins > > Howdy all, > > Kinsler fuel injection sells all the connector plugs, boots, and pins > for > bosch connectors. > > Don't know if these are the same as GM connectors, but give them a > call. > > Phone # is 313-362-1145 > > Regards > Jeff > ------------------------------ From: John Hess Date: Mon, 8 Sep 1997 16:28:43 -0500 Subject: RE: ECU box locations It varies by manufacturer, model, and/or year. My '86 Corvette has it under the dash on the passenger side. My Por$che had it in the fender well over the left rear wheel. My friend's '90 Corvette has it under the hood. > ---------- > From: Bruce Bowling[SMTP:bowling@xxx.gov] > Sent: Monday, September 08, 1997 3:15 PM > To: diy_efi@xxx.edu > Subject: ECU box locations > > Here's a question I have been meaning to ask: > > Where do auto manufacturers put the ECU boxes? Many times, > I am asked to find the ECU, and I often fail to locate them, > which makes me look like sort of an idiot. I do not know all > of the different hiding places, nor do I like tearing apart > the dash to later discover that the box is in the trunk. > I always start by tearing out the kick panel by the passenger's > compartment and start from there. Do auto manufacturers > have a tendency to put them in the same place between models? > > I know that Nissan likes putting them under the passenger's seat. > > I think that this is useful FYI for anyone on this list. > > - Bruce > > > -- > ----------------------------------------------------- > <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> > ----------------------------------------------------- > Bruce A. Bowling > Staff Scientist > Thomas Jefferson National Accelerator Facility > 12000 Jefferson Ave - Newport News, VA 23606 > (804) 249-7240 > bowling@xxx.gov/~bowling > ----------------------------------------------------- > <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> > ----------------------------------------------------- > ------------------------------ From: michaels@xxx.com (Michael Skolones) Date: Wed, 10 Sep 1997 08:05:38 -0700 Subject: Re: O2 sensor output - --IMA.Boundary.963409378 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Content-Description: cc:Mail note part For the typical, less expensive (lambda=1 setting) sensor the value at stoich is not well defined. The O2 sensor acts somewhat like a two-position switch: for lean mixtures the output is low (~0.1 V), for rich mixtures it is high (~0.8 V), but the slope of the V vs lambda curve is very steep around the stoich point where lambda=1. The ECU's job is to vary the mixture such that the O2 sensor ouput bounces back and forth regularly between these two values. I suppose you could use the average of the low and high readings from your sensor as a "perfect mixture" reading, but I doubt you'll be able to get your FI system to stay exactly at this mixture setting. The newer, more expensive sensors (around US $300 and up) have a more spread-out curve, and the numerical values of the sensor output are useful. The output value at stoich for these sensors depends on the individual sensor model, though lambda=1.2 is common (I think. Don't have one, so I'm not sure) Mike Skolones ______________________________ Reply Separator _________________________________ Subject: O2 sensor output Author: diy_efi@xxx.edu at Internet Date: 9/10/97 4:22 AM Can anyone tell me what it's the output of an O2 sensor ( it's any diference between type ?) on perfect mixture ? Alex http://home.onestop.net/nalex ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com - --IMA.Boundary.963409378 Content-Type: text/plain; charset=US-ASCII; name="RFC822 message headers" Content-Transfer-Encoding: 7bit Content-Description: cc:Mail note part Content-Disposition: inline; filename="RFC822 message headers" Received: from coulomb.eng.ohio-state.edu (128.146.90.150) by mailserver.mail1.com with SMTP (IMA Internet Exchange 2.1 Enterprise) id 000964E3; Wed, 10 Sep 97 05:36:30 - -0700 Received: by coulomb.eng.ohio-state.edu (940816.SGI.8.6.9/940406.SGI) for diy_efi-outgoing id LAA02356; Wed, 10 Sep 1997 11:21:33 GMT Received: from hotmail.com by coulomb.eng.ohio-state.edu via SMTP (940816.SGI.8.6.9/940406.SGI) for id HAA02351; Wed, 10 Sep 1997 07:21:31 - -0400 Received: (qmail 7157 invoked by uid 0); 10 Sep 1997 11:22:04 -0000 Message-ID: <19970910112204.7156.qmail@xxx.com> Received: from 161.142.213.191 by www.hotmail.com with HTTP; Wed, 10 Sep 1997 04:22:03 PDT X-Originating-IP: [161.142.213.191] From: "alex nicu" To: diy_efi@xxx.edu Subject: O2 sensor output Content-Type: text/plain Date: Wed, 10 Sep 1997 04:22:03 PDT Sender: owner-diy_efi@xxx.edu Precedence: bulk Reply-To: diy_efi@xxx.edu - --IMA.Boundary.963409378-- ------------------------------ From: James Boughton Date: Wed, 10 Sep 1997 11:46:20 -0400 Subject: RE: OBD II - fuel trims (adaptives) Basically, you weren't too far off to begin with. The short term adaptives are typically used for two purposes. First, to account for unusually rapid changes in fuel/air. A full vapor canister after a hot soak can cause this type of behavior. Second, this term is usually used to create the small oscillations in fuel/air required to make a catalyst work well. The long term adaptives are typically much more stable, relating to such things as injector drift. But the long term adaptives can move around due to conditions such as the hot soak condition mentioned above. For both long term and short term adaptives there are usually speed/load cells where the response characteristics for the short term and the adaptive value for the long term are used. In other words, it is possible that the long term adaptive at idle is different than the one for 30mph cruise and different for the one at 50mph cruise, etc. In your first example (50mph cruise) you had -7% long term. This is not terrible, since depending on who calibrated it there might be a typical -5% built in. This way if you unplug the engine controller the engine will run about 5% rich until the adaptives catch up. Also, since these are typically multipliers your 1.05*0.93=~0.98. So this is not very far off. Under WOT conditions the engine controller should, typically, run open loop. Whether or not any of the adaptives are used will vary from company to company, since it is built into the software, which changes every year. The only thing I might be concerned about is why your long term is -21%. This could be caused by the above mentioned hot soak condition where the vapors in the charcoal canister build up while the car is off, and when the car is running again these vapors come out of the canister causing a rich condition. This can eventually drive the long term adaptive to large negative numbers. Later when the canister is empty you will end up with the short term adaptive trying to correct for the long term which is what looks like is going on. However, there is definitely no feedback at WOT, so you would want to back out of the throttle slightly until the short terms starts to update to be sure you are using the adaptives that are being displayed. Oh, BTW, stoich at WOT is bad. Even though the EPA is trying to mandate it nobody currently operates stoich at WOT. When they do expect vehicle prices to rise. The engines should have some great components in them, however. Jim Boughton boughton@xxx.net - ---------- From: Joe Chiasson[SMTP:chiasson@xxx.net] Sent: Tuesday, September 09, 1997 9:58 PM To: diy_efi@xxx.edu Subject: OBD II - fuel trims (adaptives) If any one could unravel the mystery behind OBD II short and long term fuel trims (adaptives) it would be greatly appreciated. My interpretation was that short term fuel trims dealt with the short term fuel delivery (i.e. computer increasing or reducing pulsewidth to reach a stoich O2 sensor reading). My interpretation of long term fuel trims is how out of whack the fuel delivery to the engine is, either over an OBD II driving cycle or over the entire driving life of the vehicle, until the ecm is diconnected that is. This is what I thought (now please correct me if I am wrong) untill I ran into this senario with a 1997 Ford F-150 automatic 4.6 L V-8. Under cruising speeds of 55 mph the short term fuel trim was +5% and the long term fuel -7%. Under WOT conditions the short term fuel trim was +33% and the long term -21%. Now under my intial interpretations on how fuel trims were calculated I assumed that at WOT the ecm was increasing the fuel delivery by 33% to reach stoich. But then why would the long term fuel trim decrease? Well this has confused the hell out of me. If anybody can clue me on on what the fuel trims actually mean, and how they are determined (i.e. referenced off the front O2, the rear O2, or no O2 at all) help would be appreciated. J. ------------------------------ From: Todd King Date: Wed, 10 Sep 97 09:07:00 PDT Subject: Re: O2 sensor loc <<< All the Grand Nationals and Turbo Regals have the sensor in the downpipe after the turbo. >>> Really? I wonder why the factory did my '87 turbo Regal before the turbo? I guess the line workers got bored and decided to do one car that was different from all the rest... :-) If you have a non-heated sensor then you may have a hard time getting it to "stay lit" if you placed it after the turbo; heck, the GN's have a hard time lighting a non-heated at all once aftermarket headers are installed. Many who install headers also go to a heated, even though the sensor is still located before the turbo with the new headers. FYI. Todd todd_king@xxx.com ------------------------------ From: Todd King Date: Wed, 10 Sep 97 09:29:00 PDT Subject: re: SFI popping at wot I had a brief talk with Mike Lozano at Lozano Bros Porting in San Antonio; they were Buick factory sponsored with the stage 2 stuff; they did some engines for Indy as well as the Camel lights or GTP stuff (something like that). He recalls having some popping problems at one point with the indy motors (which ran SFI) under boost. Then he started talking about camshaft overlap and injector phasing, saying things like "...one phasing may be good for an rpm band but be bad for another", "...causes leaning out by dumping fuel out the exhaust", etc. He's a real nice guy but I know he is extremely busy so I didn't want to push the phone chat any longer; they aren't into the street stuff anyway. But some good food for thought... So then the light bulb started to fizzle a bit- (bzzzzzzt-fizzle-pop-bzzzzzzttt...) Say we have a small stock inj (like a 28 lb/hr GN unit) and it needs 10ms to shoot its load (sorry, better put the kids to bed now) at say 4000 rpm. And say that the stock phasing fires the inj early in the inlet cycle such that the overlap period is substantially covered by the inj firing too. Now at this rpm the overlap period is a fairly long time in ms. But the small inj spreads its shot out such that the overlap period does not see that much fuel coming in, relatively. We assume that some of the fuel goes right out the exh during the overlap period. Then go up to a 55lb inj; suddenly the pw is 1/2 what it was with the stock inj. Now the shot intensity during overlap is doubled and with similar phasing we might see twice as much fuel head out the exh during overlap as compared to the smaller inj. Make sense? Then to make things worse, throw in a turbo with a large .82 a/r exh housing and a big, efficient compressor at high airflow; now the exh manifold backpressure is substantially reduced such that there is even more tendency for fuel to be blown through during overlap. Now we get a lean pop since a substantial amount of fuel that was supposed to be in the cyl at fire time had already made a direct exit out the exh during overlap. This is when people see the pops- after installing larger inj and windy turbos. Hmmmm... Todd todd_king@xxx.com PS That new staged dual fuel pump setup arrived last night; it's gonna be a fun weekend, full of boost. Looks like I might be "forced" to slick up the car Sat night and go to where the big blocks play... ;-) ------------------------------ From: Bruce Bowling Date: Wed, 10 Sep 1997 13:58:16 EDT Subject: Pulse Width meter schematic I have posted the PIC-based FI pulse width schematic on my WWW site: http://devserve.cebaf.gov/~bowling/pwmeasure.html I believe this is the latest version of the code, but I may be wrong (I have to check). Remember, the meter *may* get fooled by peak/hold injectors - I have not had the time to fix the code to correct this yet. - - Bruce - -- - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- Bruce A. Bowling Staff Scientist Thomas Jefferson National Accelerator Facility 12000 Jefferson Ave - Newport News, VA 23606 (804) 249-7240 bowling@xxx.gov/~bowling - ----------------------------------------------------- <<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> - ----------------------------------------------------- ------------------------------ From: Neall Booth Date: Wed, 10 Sep 1997 21:22:37 -0700 Subject: Re: Propane on Fuel Injected Cars Clare Snyder wrote: > The system is not TBI, I,ve seen it and it has multiple injectors. They have > been working with FORD, were working with Chrysler, are partnered with > Martin Marietta (not sure of spelling), apparently were doing some deisel > work as well. What chrysler is using now may not be their system, but a > couple years ago they were working together. > There were dodge 4wd ambulances running with their system. Actaully, the GFI injector block is called the Compu-valve. It features two injectors and five solenoids (7 with natural gas). The solenoids open up one by one as the base fuel demand increases. The injectors provide triming fuel only, based on the O2 sensor, ECT, etc. The output of the compuvalve must then be piped into the intake somehow. While I'm not totally sure how it's accomplished, it's basically piped into the intake. It is not a multipoint system, nor is it TBI, however it is something in between. There is one example I can think of that used a manifold arragnment to pipe the gas into each seperate injector port on a 5.2L V8 engine. However, again this is not multipoint injection, and the vehicle was a research testbed built at the University of Waterloo in Ontario. Ford does use the complete system on their F150 propane package. However, Chrysler has moved away from gaseous induction and spent the last five years developing a multipoint liquid propane injection system. The system is presently installed in the Dodge fullsize van, on the 5.2L engine, and is on sale in Canada, in limited quantities. Back several years ago (10, maybe?) Chrysler did sell vehicles with gaseous induction systems on them, but that was a number of years ago. Whether or not it was a GFI system I could not tell you. Neall - -- ********************************** Neall Booth Bi-Phase Technologies Development & Applications Engineer nbooth@xxx.net ********************************** ------------------------------ From: "Joe Chiasson" Date: Wed, 10 Sep 1997 21:44:50 -0500 Subject: Re: OBD II - fuel trims (adaptives) > Basically, you weren't too far off to begin with. The short term > adaptives are typically used for two purposes. First, to account > for unusually rapid changes in fuel/air. A full vapor canister after > a hot soak can cause this type of behavior. Second, this term > is usually used to create the small oscillations in fuel/air required > to make a catalyst work well. > > The long term adaptives are typically much more stable, relating > to such things as injector drift. But the long term adaptives can > move around due to conditions such as the hot soak condition > mentioned above. If the vehicle was travelling at about 55 mph load and had a long term of say -7%, and from the time it takes to accelerate to 65 mph and return to closed loop, if in fact the computer ever left, the long term drops to - -11%, is this an acceptable amount of drift. (i.e. should the longterm numbers move this rapidly or should it be a slow transition) Based on a situation where the vehicle did not undergo a hot soak condition . > For both long term and short term adaptives there are usually speed/load > cells where the response characteristics for the short term and the > adaptive value for the long term are used. In other words, it is possible > that the long term adaptive at idle is different than the one for 30mph > cruise and different for the one at 50mph cruise, etc. In your first > example (50mph cruise) you had -7% long term. This is not terrible, > since depending on who calibrated it there might be a typical -5% built > in. This way if you unplug the engine controller the engine will run about > 5% rich until the adaptives catch up. Also, since these are typically > multipliers your 1.05*0.93=~0.98. So this is not very far off. > > Under WOT conditions the engine controller should, typically, run > open loop. Whether or not any of the adaptives are used will vary from > company to company, since it is built into the software, which changes > every year. The only thing I might be concerned about is why your > long term is -21%. This could be caused by the above mentioned > hot soak condition where the vapors in the charcoal canister build > up while the car is off, and when the car is running again these vapors > come out of the canister causing a rich condition. This can eventually > drive the long term adaptive to large negative numbers. Later when > the canister is empty you will end up with the short term adaptive trying > to correct for the long term which is what looks like is going on. However, > there is definitely no feedback at WOT, so you would want to back out > of the throttle slightly until the short terms starts to update to be sure you > are using the adaptives that are being displayed. I realize that at WOT the computer is in open loop and on most of the chryslers that I have seen there is no feedback what so ever, concerning fuel trims (i.e. diagnostics tool outputs 0% for both.) Now the fact that the F-150 did report fuel trims @xxx. You "hint" that these are probably bogus numbers and I guess I will have to agree and take that into account. However I have investigated what the fuel trims are in closed loop just after letting off WOT. My long term is around -14%, which brings me back to the question above which is how much drift is acceptable and in what period of time. The still more confusing factor is that the short term is +9%. It seems that as the pw increase the short and lon term grow apart from each other. I swapped in new O2 sensors to see if that would change anything, it brought them closer but significantly there was no change. > Oh, BTW, stoich at WOT is bad. Even though the EPA is trying > to mandate it nobody currently operates stoich at WOT. When > they do expect vehicle prices to rise. The engines should have > some great components in them, however. > > Jim Boughton > boughton@xxx.net > Thanks for the response Jim, although I am still a bit confused, I now know I'm on the right track of thinking. Much appreciated. J. ------------------------------ From: Jim Davies Date: Wed, 10 Sep 1997 20:06:54 -0700 (PDT) Subject: Re: Propane on Fuel Injected Cars On Wed, 10 Sep 1997, Neall Booth wrote: > Ford does use the complete system on their F150 propane package. > However, Chrysler has moved away from gaseous induction and spent the > last five years developing a multipoint liquid propane injection > system. The system is presently installed in the Dodge fullsize van, on > the 5.2L engine, and is on sale in Canada, in limited quantities. > > Back several years ago (10, maybe?) Chrysler did sell vehicles with > gaseous induction systems on them, but that was a number of years ago. > Whether or not it was a GFI system I could not tell you. > This package also used the 318 V8, and was available on pickups, vans and RWD cop cars. Standard Impco parts were used, so I guess you could call it TBI. BTW, they also had a 2.2 FWD propane car (never actually saw this one, only the tech stuff. All this was Canada only, IIRC. Jim Davies ------------------------------ End of DIY_EFI Digest V2 #314 ***************************** 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".