DIY_EFI Digest Friday, 29 March 1996 Volume 01 : Number 092 In this issue: Re: Multispark stuff and other thoughts off topic but interesting Re: Re[2]: injector pulse width RE: Off topic, but related subject matter... I know I know!!! RE: Off topic, but related subject matter... Re: Re[2]: injector pulse width Separate coils / knock retard. See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: "Clinton L. Corbin : Backgrind/Gold : Pager 0544" Date: Thu, 28 Mar 96 19:12:40 PST Subject: Re: Multispark stuff and other thoughts >Several OEMs are doing this or designing engines that do this, namely, > one coil per spark plug. Where's the beef? > >1) No plug wires. Like someone correctly guessed in their post, if you > have no plug wires, you don't have to contend with RFI and losses >across the wires. You still have to contend with RFI and losses within >the coil itself, but that's an existing problem. You also eliminate >one connection when you eliminate the plug wires. That's one less >thing to breakdown and leave you stranded. Sure, you just added a >bunch of 12 volt wires to the each coil, but it's much easier to deal > with 12V than 12kV-45kV. I agree that this can only be done with one coil/cylinder >2) Spark energy. Firing once every two revs means you can charge >longer and deliver more energy per spark than firing three or four >times each rev. What is the saturation time of the coil? If you are charging at a fast rate, I still see no advantage with one coil/cylinder over one coil/two cylinders. >3) Multistrike/multiple spark. You can extend the multistrike rpm >range all the way to redline instead of have to go single strike at >3000-4000rpm. Even with one coil/two cylinders you stil have four times (on a 8 cylinder) the number of coils than the MSD has. Just how high do you need to take the motor anyway? >Now it gets really interesting... > >4) Combustion sensing. You can read the resistance across the gap >after firing the plug and determine if you misfired or if it the flame >went out. You can then strike the plug again until you are satisfied >that you've burnt everything! Jacob's Electronics claim they can do >this with one coil firing many cylinders, but imagine how much better >you can do it if you have an independant circuit for each cylinder. >This is literally on demand multistrike capability and can extend your > lean limits and/or reduce feedgas emissions. Once more, with the wasted spark system, you could do all of this with out a problem. The only exception that I have heard of would be a engine with extremely long intake and exhaust duration. Not a problem on just about any engine going on the street. >5) Independant cylinder knock control. With two knock sensors, you can >determine which cylinder is knocking and alter that cylinder's spark >advance without screwing with the remaining cylinders' spark advance. Any again, why does one coil/cylinder do this any better than the wasted spark system? >So, the beef is, with coil per plug, you are one step closer to >controlling several one cylinder engines instead of controlling a V6 >or V8 or I4. There are tradeoffs, but if you really need some of these >things(especially extending the lean limits and reducing emissions), >you will pay for them. Except for the first item, almost all of this was the advantages one coil/ cylinder has over a standard distributor system, not over the wasted spark system. I am also heavily into car audio, so getting rid of one source of RFI is tempting though... Clint ccorbin@xxx.com ------------------------------ From: jac@xxx.us (john carroll) Date: Thu, 28 Mar 96 20:23:29 PST Subject: off topic but interesting The discussion of propane and cng fueled engines reminds me of a fleet of Peterbuilt log haulers that use propane introduced into the induction system to replace some of the diesel. The concept could be useful to others. The system works as follows. Advancing the pedal first causes propane vapor to be introduced to the air stream, increasing power. The diesel injectors introduce fuel at a low level and provide ignition source and timing. As the pedal is advanced, more and more propane is added. At the point where the fuel vapor displaces so much air as to destroy the economic and mechanical efficiency of the hybrid, the call for additional power increases diesel and reduces propane until, at maximum power, the engine runs entirely on diesel. It may be that transition takes place at a point where the propane/air mixture is still sufficiently lean that dentonation is not a problem, They claim that over all and particularly at mid-power operation, there is a net benefit. The value of the system is certainly a function of the relative cost of diesel and propane. Does any one think the propane was taxed? I believe they run a kiln on propane as well. I am certain the systems are commercial, but I have no idea of the source. The most exciting corollary of this system that I have observed was when a diesel powered drill rig hit a natural gas tranmission line at about six feet. Every one abandoned ship without hitting the fuel cut off and the engine ran away as the engine began inducing gas along with air. A brave soul (the owner) went back and shut the fuel off before the engine came apart or a fire started. - ----------------------------------------------- jac@xxx.us john carroll ------------------------------ From: William Sarkozy Date: Fri, 29 Mar 1996 00:03:29 -0800 Subject: Re: Re[2]: injector pulse width At 09:41 AM 3/29/96, you wrote: > > >>Per Frank "Choco" Munday's book, TPFI, he states that 305/350 injectors >>will work reasonably well if exchanged as a complete set. This refers to >>the MAF type TPI systems up to '89, and exclude your '85 baby (even though >>it's MAF equiped). His book only covers the '86-'89 models, but I think the >>injector swaping rule will apply to your system also since it's a MAF type. >>Choco goes on to say that he can not tell the difference below 4,500rpm. >>Thats big in small and small in big. >> >>There are differences in the operating pressures. Per chilton, 44psi for >>5.0 & 37psi for 5.7 > >>22lbs/hr flow rate for the 350 per Ben Watsons chevy fuel injection book (no >>305 data). > >>BTW guys, The '89 TPI in my '58 is running great! All bugs have been worked >>out and I've clocked over 600 trouble free city miles already. The R700 is >>comming soon. > >>Dan, if you can give the symtoms, I sure one of us gurus could help. > >>Good luck >>GMD > >Thanx for the info. > >The system is infact of a TPI of a 305 '85 F-body according to the fuel rail >number. However the system is now MAP sensing. Can anyone confirm that what I >have done seem right. I have the ECU water temp sensor mounted in one of the >three holes in the front of the manifold, the air temp sensor is mounted in the >hole on the underside at the back of the plenumb chamber, and the MAP ensor >vacuum line is taken of the back corner of the plenumb chamber. > >The cam is: inlet - open 23 deg, close 61 deg (I think) > exhaust - open 68 deg, close 26 deg (I think) > >The engine only seem to run evenly at a stoic of 11.5, CO=5%-7% (very rich) at >idle. When you try and improve on this and actually load up the engine, the >engine starts to jerk around quite violently and only seem to settle down >slightly in the low rpm range when you give it lots of fuel. > >Is it possible to calculate a theoretical fuel map for my computer, either a VE >value or an inject time pulse width for the rpm range that we can follow ? > >If this is possible can someone please send me the formulas ? > >By the way, I'm using the old type HEI dizzy, and when we checked the ignition, >it looked like one bank of the engine had a problem (the pulses were not all >level, but went up and down and up and down) but I have been told that the wrong >air/fuel ratio can cause this. Anyone have any ideas ? > >Is it a timing problem ? Is it a fuel problem ? > >Much help needed here > > >Dan dzorde@xxx.au > > > When my T-Bird starting running ratty, I traced the problem to a bad fuel pressure regulator....it would start out fine at power-up, then jump to 85-90 psi. I have no way of monitoring the O2 sensor, so I don't know whether the injectors had trouble opening at the high pressure, or whether it just ran super fat because of the increased pressure. If you don't have the diagnostic gear, try a remote tire pressure gage which will connect right on the fuel rail. Be careful, though.....if the Bourdon tube breaks, you'll have fuel everywhere. Bill ------------------------------ From: Terry Faugno Date: Thu, 28 Mar 1996 21:56:27 -0800 (PST) Subject: RE: Off topic, but related subject matter... I know I know!!! At 09:10 PM 3/28/96 -0600, you wrote: >Electromotive is the company that's currently working this!!! They're local >and in one of their latest catalogs I spotted this system being tested on a >VW motor. It's also been written up in Turbo magazine. It uses one of their >FI boxes to run it, pretty neat! Which issue, and what's Electromotive's phone number?!?!? Thanx, Terry ------------------------------ From: Terry Faugno Date: Thu, 28 Mar 1996 22:28:35 -0800 (PST) Subject: RE: Off topic, but related subject matter... At 09:17 PM 3/28/96 -0600, you wrote: >In case you're interested - there's a company written up in Turbo magazine >this month that's doing V8 conversions for the 911 bodystyle. It uses a >remote mounted water pump and some strange accessory routing but overall it >looks great! Let me know if you'd like more details, I might even be able >to find the Electromotive info but you'd be better off calling or writing >them, I'll look for the number - I've seen it posted recently I think... I'm aware of Renegade Hybrids and their Porsche/Chevy/American V8 conversions. What I want info on is any companies that make solenoid/non-camshaft actuated valvetrains. What's Electromotive's number? That and someone mentioned Aura... I'll be finding info on them ASAP... Thanx, Terry ------------------------------ From: arthurok@xxx.com (ARTHUR OKUN ) Date: Thu, 28 Mar 1996 23:58:03 -0800 Subject: Re: Re[2]: injector pulse width a refrigeration works fine for checking gm mpi pressure just remember to blow if clean with "air" before using on refrigeration equipment ------------------------------ From: einarp@xxx.no (Einar Sjaavik) Date: Fri, 29 Mar 96 10:13:53 CET Subject: Separate coils / knock retard. There is no need for separate coils to do knock retard on a per cylinder basis. The controller just needs to know how many cylinders it's controlling. If it's a 6cyl. engine, just wait 5 cylinders then retard the next. Do this for each and every cylinder. You could also measure the average noise level and use this to modify the threshold you define as knock. This way the influence of valve noise can be made less of a problem. On the other hand; if you have valve or bearing noise, the engine could be saved by the resulting power loss from a retard. And you have an indication something is wrong. Just remember it need not be the ignition itself. It can be an advanced state of engine wear just fooling the knock sensor. And could you please cut everything except maybe a few lines when responding? Much of the time I don't bother to search through the echo to find _your_ statement. Result is it doesn't get through. And as to the "bother" of sending attachments; please don't. - -- einarp@xxx.no ( Maserati Biturbo Spyder ) ------------------------------ End of DIY_EFI Digest V1 #92 **************************** 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".