DIY_EFI Digest Wednesday, March 31 1999 Volume 04 : Number 203 In this issue: l-jet characteristics Re: diy flow bench Re: Shutting fuel off whie driving. Re: Pre + Post O2s Re: Shutting fuel off whie driving. Re: diy-efi archives all screwed up? RE: Camshaft Selection Re: Camshaft Selection Re: Shutting fuel off whie driving. Into fluorescent lights unknown computer Re: Shutting fuel off whie driving. Into fluorescent lights l-jet characteristics Re: Shutting fuel off whie driving. Re: Shutting fuel off whie driving. Re: Shutting fuel off whie driving. Re: unknown computer Re: Shutting fuel off whie driving. RE: Camshaft Selection Re: Shutting fuel off whie driving. RE: Shutting fuel off whie driving. Re: Shutting fuel off whie driving. Re: Shutting fuel off whie driving. Re: Shutting fuel off whie driving. RE: Camshaft Selection RE: Camshaft Selection Re: Shutting fuel off whie driving. Formulas... Re: Shutting fuel off whie driving. Re: Camshaft Selection Re: Formulas... Re: Shutting fuel off whie driving. RE: Camshaft Selection Re: Shutting fuel off whie driving. See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- Date: Wed, 31 Mar 1999 20:39:42 +1000 From: ants Subject: l-jet characteristics Hi all, I have an Alfa 2.5V6 with Bosch L-Jet engine control. All this talk about fuel shutoff at overrun (well 2 posts anyway), got me to ask the question: Does L-Jet have this feature? Also, does L-Jet have an idle control speed set point? that is, when a load is present on the engine (like air-con, etc), does it try to speed up the idle to compensate for the load? I know it has the idle air bypass (IAC?) but isn't that just used on start up? If it has the idle speed control, is that set anywhere? (apart form the idle speed screw on the throttle body). Thanks for any help and for setting me straight if I am way of the mark. Anthony Sydney, Australia. ------------------------------ Date: Wed, 31 Mar 1999 13:05:37 +0200 From: "Espen Hilde" Subject: Re: diy flow bench Thanks for the article, interesting reading...... One tought that I cant get out of my head , is when you are using just a cuple of the engines to pump, will not the rest of the engines compressors leak the opposite way? John Dalton sugests in his book Practical Gas Flow (isbn 0-947981-33-0) that its good enought to use one vacum cleaner/or two.....variable bleed valve and a differential pressure gauge(in inches of water) He has some interesting anti reversion rachets made to the valves and ports. I have tryed it and it works. Espen Hilde ------------------------------ Date: Wed, 31 Mar 1999 09:25:41 EST From: ECMnut@xxx.com Subject: Re: Shutting fuel off whie driving. As an "electronocally challeged" participant, I'd use a resistor and an led connected to the injector harness. Not sure of the exact value. If you have constant LED activity while accellerating, but none during coast-down, you have your answer.. HTH Mike V > Does this happen in an L-JET? > Is there a way I can test the injector output while > driving to see if they are being fired at coast? ------------------------------ Date: Wed, 31 Mar 1999 09:51:42 -0500 From: "Gary Derian" Subject: Re: Pre + Post O2s The first cats were oxidizing only. Engines ran lean so there was excess O2 to promote oxidation, HC and CO became H2O and CO2. This left NOx untreated because it requires a reduction reaction which is not possible in an oxidizing atmosphere. Running a cat at stochiometric and adding rhodium and palladium to the mix permitted both ox and red reactions to take place. The 3 way name is because it treats all 3 regulated emissions. HC and CO become H2O and CO2 and NOx becomes N2 and the oxygen is used in the HC and CO reactions. Overall, cats add heat. The cat has some O2 storage capacity, the post cat sensor therefore swings more slowly than the pre cat sensor. As the cat becomes ineffective, the post cat sensor swings with the pre cat sensor setting off the SES light. Gary Derian > As I understand things, the cat converters are a reducing chemical reaction, > so > they consum calories to react. (True or False?). > > The rear O2 sensor would run cooler then the front. > > So, the rear O2 in order to measure the effectiveness of the cat would need > to > operate at least at the same temp as the front. So it would need a "better" > heater. > > Since it might not track the front too well, then it's "range" would need to > be greater. > > Only have any documents to compare the above to, or does it make sense > to someone other than me?. > Bashful > ------------------------------ Date: Wed, 31 Mar 1999 10:32:37 -0500 From: Frederic Breitwieser Subject: Re: Shutting fuel off whie driving. > As an "electronocally challeged" participant, Being a non-electronically challenged participant, I will add... > I'd use a resistor and an led connected to the > injector harness. Not sure of the exact value. A generic Radioshack LED with a 1K ohm resistor in series would display light when the injector is fired, however even at idle, it would be difficult to see it going on and off. Lets see why. Assume a V8. On true sequential injection, one injector pulse per intake stroke, would result in 50 injector pulses per rotation at an idle of 800 RPM. 800 rpm / 8 cyls = 100, 100 / 2 (four stroke) = 50. At 800 RPM, the led would pulse at or about 50 hz, which your eye really cannot see, and would view as constant illumination. Flourescent lights actually flicker on and off 60 times a second, and the light appears constant to most people, thus illustrating my point. > If you have constant LED activity while accellerating, > but none during coast-down, you have your answer.. Often on deceleration, the injector just misses certain cycles, and is not closed off entirely, therefore the LED would still be on more often than not. And oscilloscope would help :) - -- Frederic Breitwieser Bridgeport CT 06606 1993 Supercharged Lincoln Continental 1989 HWMMV w/turbocharged 500cid Caddy 1975 Dodge D200 Club Cab soon to have 431 stroker + turbos 2000 (I hope) Buick GTP (Mid-Engined Sports Car) ------------------------------ Date: Wed, 31 Mar 1999 09:31:11 -0600 From: steve ravet Subject: Re: diy-efi archives all screwed up? They seem like they're working fine for me this morning. What searches are y'all having problems with? - --steve Bruce Plecan wrote: > > -----Original Message----- > From: andy quaas > To: diy efi > Date: Tuesday, March 30, 1999 7:20 PM > Subject: diy-efi archives all screwed up? > > Now there are no results to searches, > Bruce > > >Is it just me or do i see 10 copies of all the results of my searches in > >the archives? Will someone go in and do a search and tell me if i fell > >this morning and don't remember it...? > > > >andy > > > >_________________________________________________________ > >Do You Yahoo!? > >Get your free @xxx.com > > - -- Steve Ravet steve.ravet@xxx.com Advanced Risc Machines, Inc. www.arm.com ------------------------------ Date: Wed, 31 Mar 1999 11:26:32 -0500 From: "Gwyn Reedy" Subject: RE: Camshaft Selection Carl and others that commented earlier on my camshaft choice. With 3.08 rear end (kinda high for towing) and 255/70x15 tires I think I'm never getting over 3000 RPM at any towing speeds. Don't have a tach in the truck - saving for the tach in the dash to match all the other gauges. Here is what I decided to do - actually have done. The cam is already in the engine, but not yet in the truck. Stock cam, I believe is 193/203 duration and .409/.442 lift. Lobe separation is listed as 104/116 (not sure if I understand why there are two numbers....) What I put in: 204/214 duration, .476/.502 lift and 107/117 separation. Also put new 1.7 ratio rockers and Rhodes bleed-down lifters. Hope is that the lifters will make the cam look just about the same as the stocker at 2200 RPM and less and then pump up and give the benefit of the increased lift above 3-3500 RPM. Trying to get the best of both worlds. Will tell you all how it runs in a month or so after it is back together. For higher performance driving I'll eventually get my 69 El Camino with 396 back on the road. Being a used car I don't know what cam is in it, but it sure idles rough . Gwyn Reedy Brandon, Florida mailto:mgr@xxx.com '72 Cheyenne half ton (driver)(actually a rebuilder also, at the moment) '69 El Camino SS396 (rebuilder) > -----Original Message----- > From: owner-diy_efi@xxx.edu > [mailto:owner-diy_efi@xxx.edu]On Behalf Of > EFISYSTEMS@xxx.com > Sent: Wednesday, March 31, 1999 12:14 AM > To: diy_efi@xxx.edu > Subject: Re: Camshaft Selection > > > Hi Gwyn, > What RPM do you usually tow at?????? > -Carl Summers > > In a message dated 99-03-15 10:31:58 EST, you write: > > << Subj: Camshaft Selection > Date: 99-03-15 10:31:58 EST > From: mgr@xxx.com (Gwyn Reedy) > Sender: owner-diy_efi@xxx.edu > Reply-to: diy_efi@xxx.edu > To: sixtiestrucks-l@xxx.org (Sixties Truck List), > diy_efi@xxx.org (CK > Series List), chevelle@xxx.com (Chevelle List) > > I have the 402 BBC out of my 72 Cheyenne pickup torn down for a rebuild. > Dang oil pump inlet fell off and the bearings got fed a mixture > of oil and > air... > > The engine is not very badly damaged. Taking the crank in today > to see what > it needs done to it, but it doesn't look very bad at all. > > The cam shows a lot of wear. Looks like the original cam with > 70k miles on > it. Some of the lifters are starting to get concave a bit too. > > The truck is used for running errands around town, and from time to time > pulling a heavy trailer. The trailer is 6000 lbs empty and up to 14000 > loaded. 3.08 posi rear end and THM-400. > > Wondering what cam to put in it. This is an oval port (passenger car type > heads) with a low profile Quadrajet manifold, standard cast iron exhaust > manifolds. Need low end torque, not horsepower. > > I'm wondering if any of these 'bottom-end torque for 4x4 off > road use' cams > might be a good choice or should I just put a replacement > factory cam back > in it? > > Gwyn Reedy > Brandon, Florida > mailto:mgr@xxx.com > '72 Cheyenne half ton (driver) > '69 El Camino SS396 (rebuilder) > > > > >> > ------------------------------ Date: Wed, 31 Mar 1999 11:55:18 -0500 From: "David A. Cooley" Subject: Re: Camshaft Selection Gwyn, Not sure what engine management you have (ECM etc) but the Ford, Chrysler and GM units have TONS of problems when you run Rhodes lifters... Knock retard goes through the roof as they seem to resonate at the freq the Knock sensor likes to hear... Know plenty of people that put them in with a bigger cam and wound up tearing them out and going with standard lifters as it totally killed the performance due to the constantly retarded timing. - -----Original Message----- From: Gwyn Reedy To: diy_efi@xxx.edu> Date: Wednesday, March 31, 1999 11:55 AM Subject: RE: Camshaft Selection >Carl and others that commented earlier on my camshaft choice. > >With 3.08 rear end (kinda high for towing) and 255/70x15 tires I think I'm >never getting over 3000 RPM at any towing speeds. Don't have a tach in the >truck - saving for the tach in the dash to match all the other gauges. > >Here is what I decided to do - actually have done. The cam is already in the >engine, but not yet in the truck. > >Stock cam, I believe is 193/203 duration and .409/.442 lift. Lobe separation >is listed as 104/116 (not sure if I understand why there are two >numbers....) > >What I put in: 204/214 duration, .476/.502 lift and 107/117 separation. Also >put new 1.7 ratio rockers and Rhodes bleed-down lifters. Hope is that the >lifters will make the cam look just about the same as the stocker at 2200 >RPM and less and then pump up and give the benefit of the increased lift >above 3-3500 RPM. Trying to get the best of both worlds. Will tell you all >how it runs in a month or so after it is back together. > >For higher performance driving I'll eventually get my 69 El Camino with 396 >back on the road. Being a used car I don't know what cam is in it, but it >sure idles rough . > >Gwyn Reedy >Brandon, Florida >mailto:mgr@xxx.com >'72 Cheyenne half ton (driver)(actually a rebuilder also, at the moment) >'69 El Camino SS396 (rebuilder) > > > >> -----Original Message----- >> From: owner-diy_efi@xxx.edu >> [mailto:owner-diy_efi@xxx.edu]On Behalf Of >> EFISYSTEMS@xxx.com >> Sent: Wednesday, March 31, 1999 12:14 AM >> To: diy_efi@xxx.edu >> Subject: Re: Camshaft Selection >> >> >> Hi Gwyn, >> What RPM do you usually tow at?????? >> -Carl Summers >> >> In a message dated 99-03-15 10:31:58 EST, you write: >> >> << Subj: Camshaft Selection >> Date: 99-03-15 10:31:58 EST >> From: mgr@xxx.com (Gwyn Reedy) >> Sender: owner-diy_efi@xxx.edu >> Reply-to: diy_efi@xxx.edu >> To: sixtiestrucks-l@xxx.org (Sixties Truck List), >> diy_efi@xxx.org (CK >> Series List), chevelle@xxx.com (Chevelle List) >> >> I have the 402 BBC out of my 72 Cheyenne pickup torn down for a rebuild. >> Dang oil pump inlet fell off and the bearings got fed a mixture >> of oil and >> air... >> >> The engine is not very badly damaged. Taking the crank in today >> to see what >> it needs done to it, but it doesn't look very bad at all. >> >> The cam shows a lot of wear. Looks like the original cam with >> 70k miles on >> it. Some of the lifters are starting to get concave a bit too. >> >> The truck is used for running errands around town, and from time to time >> pulling a heavy trailer. The trailer is 6000 lbs empty and up to 14000 >> loaded. 3.08 posi rear end and THM-400. >> >> Wondering what cam to put in it. This is an oval port (passenger car type >> heads) with a low profile Quadrajet manifold, standard cast iron exhaust >> manifolds. Need low end torque, not horsepower. >> >> I'm wondering if any of these 'bottom-end torque for 4x4 off >> road use' cams >> might be a good choice or should I just put a replacement >> factory cam back >> in it? >> >> Gwyn Reedy >> Brandon, Florida >> mailto:mgr@xxx.com >> '72 Cheyenne half ton (driver) >> '69 El Camino SS396 (rebuilder) >> >> >> >> >> >> > > ------------------------------ Date: Wed, 31 Mar 1999 12:09:26 EST From: A70Duster@xxx.com Subject: Re: Shutting fuel off whie driving. Into fluorescent lights Sorry for the "analness" << Fluorescent lights actually flicker on and off 60 times a second, and the light appears constant to most people, thus illustrating my point. >> Actually fluorescent lights flicker on and off 120 times a second. Fluorescent lights flicker on the positive side AND negative side of the power "sine" wave or twice during a cycle (Hertz). So it's 2*60 or 120 times a second. Resume DIY EFI!!!!!!!! ------------------------------ Date: Wed, 31 Mar 1999 10:42:33 -0700 From: cwagner@xxx.net Subject: unknown computer I was given a GM computer that was not labelled and don't know what kind it is. The EPROM chip has a label with ABYU on it. I could use some ideas on what computer it is and what it was used in and if it could be reprogramed easily. ------------------------------ Date: Wed, 31 Mar 1999 17:50:24 +0000 From: Frederic Breitwieser Subject: Re: Shutting fuel off whie driving. Into fluorescent lights > Sorry for the "analness" Tis okay, knowledge is power. > Actually fluorescent lights flicker on and off 120 times a second. Okay ;) > Resume DIY EFI!!!!!!!! We were talking EFI, my flourescent thing was nothing more than an analogy :) - -- Frederic Breitwieser Bridgeport, CT 06606 http://www.xephic.dynip.com 1993 Superchaged Lincoln Continental 1989 500cid Turbocharged HWMMV 1975 Dodge D200 Club Cab (soon to be twin turbo 440) 2000 Buick GTP (twin turbo V6) ------------------------------ Date: Wed, 31 Mar 1999 11:14:00 -0500 From: dave.williams@xxx.us (Dave Williams) Subject: l-jet characteristics - -> Also, does L-Jet have an idle control speed set point? that is, when - -> a load is present on the engine (like air-con, etc), does it try to - -> speed up the Mine, which came from an '82 Supra, uses a vacuum type idle kickup plunger wired to the air conditioning. - -> If it has the idle speed control, is that set anywhere? (apart form - -> the idle speed screw on the throttle body). Mine just has the air bypass in the throttle body. ------------------------------ Date: Wed, 31 Mar 1999 12:13:34 -0600 (CST) From: Roger Heflin Subject: Re: Shutting fuel off whie driving. On Wed, 31 Mar 1999, Frederic Breitwieser wrote: > > As an "electronocally challeged" participant, > > Being a non-electronically challenged participant, I will add... > > > I'd use a resistor and an led connected to the > > injector harness. Not sure of the exact value. > > A generic Radioshack LED with a 1K ohm resistor in series would > display light when the injector is fired, however even at idle, it > would be difficult to see it going on and off. Lets see why. > > Assume a V8. > On true sequential injection, one injector pulse per intake stroke, > would result in 50 injector pulses per rotation at an idle of 800 > RPM. 800 rpm / 8 cyls = 100, 100 / 2 (four stroke) = 50. > The intensity would vary, but I don't think that could be detected either. > At 800 RPM, the led would pulse at or about 50 hz, which your eye > really cannot see, and would view as constant illumination. > Flourescent lights actually flicker on and off 60 times a second, and > the light appears constant to most people, thus illustrating my point. > I am not sure they actually go completely off, the phospor may last long enough to hide the fact. To convince me someone would need to point a camara runing at over 120 fps and actually see if being off, my guess is it would just be dimmer during the off region, since if it were going off it should have weird strobe affects with most computer monitors. > > If you have constant LED activity while accellerating, > > but none during coast-down, you have your answer.. > > Often on deceleration, the injector just misses certain cycles, and is > not closed off entirely, therefore the LED would still be on more > often than not. > > And oscilloscope would help :) > A true RMS voltmeter may be able to tell. You should be able to get some idea of the duty cycle by the true rms voltage (a voltmeter that integrates over time, as opposed to the cheaper kind that just multiplies the max voltage by a fudge factor when in AC mode). On decel the voltage should be really low. With a simple integrating circuit/lag filter you should also be able to get some idea with a non true rms voltmeter. Wasn't someone going to do a pic circuit to display pulsewidths? Additional question: pics are simple enough that if I already had alot of electronics knowledge that the advanced book would be enough for me to work with one? Is there anyplace on internet that has the datasheets for pics? I really believe that I probably have enough electronics that the datasheets will be enought for me. Roger ------------------------------ Date: Wed, 31 Mar 1999 13:36:36 -0400 From: "Ord Millar" Subject: Re: Shutting fuel off whie driving. - -----Original Message----- From: Frederic Breitwieser To: diy_efi@xxx.edu> Date: Wednesday, March 31, 1999 1:50 PM Subject: Re: Shutting fuel off whie driving. >> As an "electronocally challeged" participant, > >Being a non-electronically challenged participant, I will add... > >> I'd use a resistor and an led connected to the >> injector harness. Not sure of the exact value. > >A generic Radioshack LED with a 1K ohm resistor in series would >display light when the injector is fired, however even at idle, it >would be difficult to see it going on and off. Lets see why. > >Assume a V8. >On true sequential injection, one injector pulse per intake stroke, >would result in 50 injector pulses per rotation at an idle of 800 >RPM. 800 rpm / 8 cyls = 100, 100 / 2 (four stroke) = 50. > >At 800 RPM, the led would pulse at or about 50 hz, which your eye >really cannot see, and would view as constant illumination. Wait a minute. Number of cylinders has nothing to do with it. If the engine is at 800 RPM, any one injector will fire 400 times / minute, or 6.6 times / second. Flashing at this rate would not appear as constant. However, the pulse width at idle would be so short that we might not even see it flicker. In fact, the duty cycle will always be so low (12.5% max on 8 cyl) that the LED will only ever appear dimly lit at best. ------------------------------ Date: Wed, 31 Mar 1999 14:11:08 -0500 From: "David A. Cooley" Subject: Re: Shutting fuel off whie driving. >Flashing at this rate would not appear as constant. However, the pulse >width at idle would be so short that we might not even see it flicker. In >fact, the duty cycle will always be so low (12.5% max on 8 cyl) that the LED >will only ever appear dimly lit at best. > > When we talk duty cycle on any engine's injectors, is it the percentage of open time to time between intake events or percentage of open time to closed time regardless of RPM etc... Reason I ask, is if my V6 is at 5200 RPM (see's it at least once a day!) then it is running 5200/60/2 43.3 intake cycles per second or intake events every 23.1ms. With a 23.1ms injector PW, that would be 100% duty cycle correct? ------------------------------ Date: Wed, 31 Mar 1999 14:42:19 -0500 From: Shannen Durphey Subject: Re: unknown computer cwagner@xxx.net wrote: > > I was given a GM computer that was not labelled and don't know > what kind it is. The EPROM chip has a label with ABYU on it. I > could use some ideas on what computer it is and what it was used > in and if it could be reprogramed easily. Found my reference book. ABYU/4317 and ABYU/9010 fit 1986 3.8l HO (VIN 3) A body cars (Buick Century).ECM# is 1227148 Shannen ------------------------------ Date: Wed, 31 Mar 1999 14:15:46 -0600 From: steve ravet Subject: Re: Shutting fuel off whie driving. > Additional question: > > pics are simple enough that if I already had alot of electronics > knowledge that the advanced book would be enough for me to work with > one? Is there anyplace on internet that has the datasheets for pics? > I really believe that I probably have enough electronics that the > datasheets will be enought for me. Ladies and gentlemen, it sounds like we have a volunteer. The place to start is www.microchip.com, the manufacturer's WWW page. From there you can get to hobbyist pages and really find a blizzard of information. There is a PIC that has support for LCD displays, and surplus 1-4 line LCD displays can be had cheaply ($10 range) at www.eio.com. The PIC is easy electronically. If you're not used to assembly the programming might take getting used to. Go Roger! - --steve - -- Steve Ravet steve.ravet@xxx.com Advanced Risc Machines, Inc. www.arm.com ------------------------------ Date: Wed, 31 Mar 1999 14:19:57 -0600 (CST) From: "Gregory A. Parmer" Subject: RE: Camshaft Selection On Wed, 31 Mar 1999, Gwyn Reedy wrote: > What I put in: 204/214 duration, .476/.502 lift and 107/117 separation. Also > put new 1.7 ratio rockers and Rhodes bleed-down lifters. Hope is that the > lifters will make the cam look just about the same as the stocker at 2200 > RPM and less and then pump up and give the benefit of the increased lift > above 3-3500 RPM. Trying to get the best of both worlds. Will tell you all > how it runs in a month or so after it is back together. Ahem...I'm got those lifters in my car. It brought back some of the low end, but they make the car sound like an old 6cyl Ford Fairlane and at this point I believe 1 or more of the lifters has worn out. It was an experiment that showed a bit of improvement for awhile, but listening to them and dealing with the differences caused by the temp of the oil will prevent me from doing it again. Maybe you'll have a higher opinion of them. FI content: this is the same car that I'm converting to TBI. Makes tuning a bi$%&! $0.02 - -greg ------------------------------ Date: Wed, 31 Mar 1999 14:30:35 -0600 (CST) From: Roger Heflin Subject: Re: Shutting fuel off whie driving. On Wed, 31 Mar 1999, David A. Cooley wrote: > > >Flashing at this rate would not appear as constant. However, the pulse > >width at idle would be so short that we might not even see it flicker. In > >fact, the duty cycle will always be so low (12.5% max on 8 cyl) that the > LED > >will only ever appear dimly lit at best. > > > > > > When we talk duty cycle on any engine's injectors, is it the percentage of > open time to time between intake events or percentage of open time to closed > time regardless of RPM etc... > Reason I ask, is if my V6 is at 5200 RPM (see's it at least once a day!) > then it is running 5200/60/2 43.3 intake cycles per second or intake events > every 23.1ms. With a 23.1ms injector PW, that would be 100% duty cycle > correct? > I think in the case above he is talking about duty cycle on the led so 100% useable injector duty cycle would be 50% duty cycle on the led. Roger ------------------------------ Date: Wed, 31 Mar 1999 12:33:57 -0800 From: "James Montebello" Subject: RE: Shutting fuel off whie driving. > pics are simple enough that if I already had alot of electronics > knowledge that the advanced book would be enough for me to work with > one? Is there anyplace on internet that has the datasheets for pics? > I really believe that I probably have enough electronics that the > datasheets will be enought for me. The manufacturer's page, http://www.microchip.com, has everything you need. james montebello ------------------------------ Date: Wed, 31 Mar 1999 14:47:16 -0600 From: steve ravet Subject: Re: Shutting fuel off whie driving. "David A. Cooley" wrote: > > >Flashing at this rate would not appear as constant. However, the pulse > >width at idle would be so short that we might not even see it flicker. In > >fact, the duty cycle will always be so low (12.5% max on 8 cyl) that the > LED > >will only ever appear dimly lit at best. > > > > > > When we talk duty cycle on any engine's injectors, is it the percentage of > open time to time between intake events or percentage of open time to closed > time regardless of RPM etc... > Reason I ask, is if my V6 is at 5200 RPM (see's it at least once a day!) > then it is running 5200/60/2 43.3 intake cycles per second or intake events > every 23.1ms. With a 23.1ms injector PW, that would be 100% duty cycle > correct? Yes. duty cycle is always "on time" as a percentage of "on time" plus "off time". The fact that it's a car, and there's some kind of intake event somewhere, does not bear on making duty cycle measurements. the sum of on+off time does change with RPM, but the formula on/(on+off) doesn't change. - --steve - -- Steve Ravet steve.ravet@xxx.com Advanced Risc Machines, Inc. www.arm.com ------------------------------ Date: Wed, 31 Mar 1999 15:07:47 -0500 From: Barry Tisdale Subject: Re: Shutting fuel off whie driving. Factor of 60 missing? Where's the Hz (seconds) to RPM (minute) divisor? At 10:32 AM 3/31/99 -0500, you wrote: >> As an "electronocally challeged" participant, > >Being a non-electronically challenged participant, I will add... > >> I'd use a resistor and an led connected to the >> injector harness. Not sure of the exact value. > >A generic Radioshack LED with a 1K ohm resistor in series would >display light when the injector is fired, however even at idle, it >would be difficult to see it going on and off. Lets see why. > >Assume a V8. >On true sequential injection, one injector pulse per intake stroke, >would result in 50 injector pulses per rotation at an idle of 800 >RPM. 800 rpm / 8 cyls = 100, 100 / 2 (four stroke) = 50. > >At 800 RPM, the led would pulse at or about 50 hz, which your eye >really cannot see, and would view as constant illumination. >Flourescent lights actually flicker on and off 60 times a second, and >the light appears constant to most people, thus illustrating my point. > >> If you have constant LED activity while accellerating, >> but none during coast-down, you have your answer.. > >Often on deceleration, the injector just misses certain cycles, and is >not closed off entirely, therefore the LED would still be on more >often than not. > >And oscilloscope would help :) > >-- > >Frederic Breitwieser >Bridgeport CT 06606 > >1993 Supercharged Lincoln Continental >1989 HWMMV w/turbocharged 500cid Caddy >1975 Dodge D200 Club Cab soon to have 431 stroker + turbos >2000 (I hope) Buick GTP (Mid-Engined Sports Car) > > > ------------------------------ Date: Wed, 31 Mar 1999 16:11:57 -0500 From: "Bruce Plecan" Subject: Re: Shutting fuel off whie driving. Just for grins I actually hooked up a LED (well it already was). On a 1227749, running a stock (sy) prom, I could easy see the injectors "firing" at idle, the "flicker" was present till about 1600 rpm.. Ign ition pulses rpm had to be about 200 rpm, by 300 light just looked to be faintly "on". Cheers Bruce ------------------------------ Date: Wed, 31 Mar 1999 16:11:47 -0500 From: "Gwyn Reedy" Subject: RE: Camshaft Selection I have used these lifters in a previous vehicle and I had no problems with them. Seemed to work as advertised, but I had no objective way to measure performance. I like the concept, at least. (Sometimes when you like the specifications, you imagine a performance improvement....) I see another manufacturer is also making this type of lifter and claiming they are not noisy, so that might be a solution for the people with knock sensor problems. Gwyn Reedy Brandon, Florida mailto:mgr@xxx.com > -----Original Message----- > From: owner-diy_efi@xxx.edu > [mailto:owner-diy_efi@xxx. > Parmer > Sent: Wednesday, March 31, 1999 3:20 PM > To: diy_efi@xxx.edu > Subject: RE: Camshaft Selection > > > > On Wed, 31 Mar 1999, Gwyn Reedy wrote: > > What I put in: 204/214 duration, .476/.502 lift and 107/117 > separation. Also > > put new 1.7 ratio rockers and Rhodes bleed-down lifters. Hope > is that the > > lifters will make the cam look just about the same as the > stocker at 2200 > > RPM and less and then pump up and give the benefit of the increased lift > > above 3-3500 RPM. Trying to get the best of both worlds. Will > tell you all > > how it runs in a month or so after it is back together. > > Ahem...I'm got those lifters in my car. It brought back some of the > low end, but they make the car sound like an old 6cyl Ford Fairlane > and at this point I believe 1 or more of the lifters has worn out. > It was an experiment that showed a bit of improvement for awhile, but > listening to them and dealing with the differences caused by the > temp of the oil will prevent me from doing it again. Maybe you'll > have a higher opinion of them. > > FI content: this is the same car that I'm converting to TBI. Makes > tuning a bi$%&! > > $0.02 > -greg > ------------------------------ Date: Wed, 31 Mar 1999 16:11:31 -0500 From: "Gwyn Reedy" Subject: RE: Camshaft Selection David, I'm running an old fashion Quadrajet. No electronics at all. (So why am I talking about it on the DIY-EFI list? More engine expertise here than anywhere else I've found.) Gwyn (W1BEL FYI) > -----Original Message----- > From: owner-diy_efi@xxx.edu > [mailto:owner-diy_efi@xxx. > Cooley > Sent: Wednesday, March 31, 1999 11:55 AM > To: diy_efi@xxx.edu > Subject: Re: Camshaft Selection > > > Gwyn, > Not sure what engine management you have (ECM etc) but the Ford, Chrysler > and GM units have TONS of problems when you run Rhodes lifters... Knock > retard goes through the roof as they seem to resonate at the freq > the Knock > sensor likes to hear... > Know plenty of people that put them in with a bigger cam and wound up > tearing them out and going with standard lifters as it totally killed the > performance due to the constantly retarded timing. > ------------------------------ Date: Wed, 31 Mar 1999 15:21:42 -0600 (CST) From: Roger Heflin Subject: Re: Shutting fuel off whie driving. On Wed, 31 Mar 1999, steve ravet wrote: > > > Additional question: > > > > pics are simple enough that if I already had alot of electronics > > knowledge that the advanced book would be enough for me to work with > > one? Is there anyplace on internet that has the datasheets for pics? > > I really believe that I probably have enough electronics that the > > datasheets will be enought for me. > > Ladies and gentlemen, it sounds like we have a volunteer. The place to > start is www.microchip.com, the manufacturer's WWW page. From there you > can get to hobbyist pages and really find a blizzard of information. > There is a PIC that has support for LCD displays, and surplus 1-4 line > LCD displays can be had cheaply ($10 range) at www.eio.com. The PIC is > easy electronically. If you're not used to assembly the programming > might take getting used to. Go Roger! > > --steve I will take a look at it. I take it that the assmebly part is the part that the skill is missing on? I have done assembly a few times (on a Z80, on a TI99/4A, a 6809, a 68hc11, a 68000, and on a 8086) so I might as well add another, I cannot see it being worse than microcode (the below assembly stuff that tells the assembly instructions what they do), and I did some of that in college. Roger ------------------------------ Date: Wed, 31 Mar 1999 16:16:20 -0500 From: "David A. Cooley" Subject: Formulas... How many grams to a pound? Trying to convert my injectors flow rate (2.4642 G/Sec) to Lbs/hr... Thanks, Dave ------------------------------ Date: Wed, 31 Mar 1999 12:20:11 -0800 From: Mike Brown Subject: Re: Shutting fuel off whie driving. I think this is closer... 800 rpm / 8 cylinders = 100 rpm 100 rpm / 2 cycles = 50 rpm 50 rpm / 60 seconds_per_minute = .833 rps (seconds) freq = 1/.833 = 1.2 Hz mike Frederic Breitwieser wrote: > > > As an "electronocally challeged" participant, > > Being a non-electronically challenged participant, I will add... > > > I'd use a resistor and an led connected to the > > injector harness. Not sure of the exact value. > > A generic Radioshack LED with a 1K ohm resistor in series would > display light when the injector is fired, however even at idle, it > would be difficult to see it going on and off. Lets see why. > > Assume a V8. > On true sequential injection, one injector pulse per intake stroke, > would result in 50 injector pulses per rotation at an idle of 800 > RPM. 800 rpm / 8 cyls = 100, 100 / 2 (four stroke) = 50. > > At 800 RPM, the led would pulse at or about 50 hz, which your eye > really cannot see, and would view as constant illumination. > Flourescent lights actually flicker on and off 60 times a second, and > the light appears constant to most people, thus illustrating my point. > > > If you have constant LED activity while accellerating, > > but none during coast-down, you have your answer.. > > Often on deceleration, the injector just misses certain cycles, and is > not closed off entirely, therefore the LED would still be on more > often than not. > > And oscilloscope would help :) > > -- > > Frederic Breitwieser > Bridgeport CT 06606 > > 1993 Supercharged Lincoln Continental > 1989 HWMMV w/turbocharged 500cid Caddy > 1975 Dodge D200 Club Cab soon to have 431 stroker + turbos > 2000 (I hope) Buick GTP (Mid-Engined Sports Car) ------------------------------ Date: Wed, 31 Mar 1999 17:09:24 -0500 From: "Gary Derian" Subject: Re: Camshaft Selection I got a set of Rhoads lifters way back in 1968. Trouble is they don't work as they claim. Letting lifters leak down only reduces lift, not duration. Plus, oil viscosity varies greatly in an engine. If they were a good idea, OEMs would all be using them. Gary Derian > > On Wed, 31 Mar 1999, Gwyn Reedy wrote: > > What I put in: 204/214 duration, .476/.502 lift and 107/117 separation. Also > > put new 1.7 ratio rockers and Rhodes bleed-down lifters. Hope is that the > > lifters will make the cam look just about the same as the stocker at 2200 > > RPM and less and then pump up and give the benefit of the increased lift > > above 3-3500 RPM. Trying to get the best of both worlds. Will tell you all > > how it runs in a month or so after it is back together. ------------------------------ Date: Wed, 31 Mar 1999 17:05:43 -0500 From: "Gary Derian" Subject: Re: Formulas... About 453.50237. I just use 454 and think big block Chevy Gary Derian > How many grams to a pound? > Trying to convert my injectors flow rate (2.4642 G/Sec) to Lbs/hr... > Thanks, > Dave > ------------------------------ Date: Wed, 31 Mar 1999 15:16:11 -0700 From: bearbvd@xxx.net (Greg Hermann) Subject: Re: Shutting fuel off whie driving. >>Flashing at this rate would not appear as constant. However, the pulse >>width at idle would be so short that we might not even see it flicker. In >>fact, the duty cycle will always be so low (12.5% max on 8 cyl) that the >LED >>will only ever appear dimly lit at best. >> >> > >When we talk duty cycle on any engine's injectors, is it the percentage of >open time to time between intake events or percentage of open time to closed >time regardless of RPM etc... - ----------------------------------------------- >Reason I ask, is if my V6 is at 5200 RPM (see's it at least once a day!) >then it is running 5200/60/2 43.3 intake cycles per second or intake events >every 23.1ms. With a 23.1ms injector PW, that would be 100% duty cycle >correct? YES--Dave, you are correct with this statement! Greg ------------------------------ Date: Wed, 31 Mar 1999 17:18:53 -0500 From: "David A. Cooley" Subject: RE: Camshaft Selection At 04:11 PM 3/31/99 -0500, you wrote: >David, > >I'm running an old fashion Quadrajet. No electronics at all. (So why am I >talking about it on the DIY-EFI list? More engine expertise here than >anywhere else I've found.) > Ah... Shouldn't be a problem then unless you go to some sort of electronic engine management with a knock sensor! 73, Dave =========================================================== David Cooley N5XMT Internet: N5XMT@xxx.net Packet: N5XMT@xxx. Member #7068 I am Pentium of Borg...division is futile...you will be approximated. =========================================================== ------------------------------ Date: Wed, 31 Mar 1999 17:46:41 -0500 From: "Bruce Plecan" Subject: Re: Shutting fuel off whie driving. - -----Original Message----- From: Greg Hermann To: diy_efi@xxx.edu> Date: Wednesday, March 31, 1999 5:30 PM Subject: Re: Shutting fuel off whie driving. >>>Flashing at this rate would not appear as constant. However, the pulse >>>width at idle would be so short that we might not even see it flicker. In >>>fact, the duty cycle will always be so low (12.5% max on 8 cyl) that the >>LED >>>will only ever appear dimly lit at best. > >>When we talk duty cycle on any engine's injectors, is it the percentage of >>open time to time between intake events or percentage of open time to closed >>time regardless of RPM etc... >----------------------------------------------- >>Reason I ask, is if my V6 is at 5200 RPM (see's it at least once a day!) >>then it is running 5200/60/2 43.3 intake cycles per second or intake events >>every 23.1ms. With a 23.1ms injector PW, that would be 100% duty cycle >>correct? > >YES--Dave, you are correct with this statement! Uh, for SEFI, only right?. Batch fire 1/2 of that. Bruce > >Greg > > ------------------------------ End of DIY_EFI Digest V4 #203 ***************************** 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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