DIY_EFI Digest Wednesday, 28 February 1996 Volume 01 : Number 059 In this issue: Re: Injector driver chips? Where? T-Coupe Intercooler Re: Thoughts on crank angle sensing Re: Thoughts on crank angle sensing re: DIY injector driver Re: Injector driver chips? Where? Re: Thoughts on crank angle sensing Re: Thoughts on crank angle sensing RE: Thoughts on crank angle sensing Basics of the timing advance Weber See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Sandy Date: Tue, 27 Feb 1996 14:21:05 -0500 Subject: Re: Injector driver chips? Where? One thing that National IS very good about it getting samples, I got a rail of 40 of the lm1949's. I think that it is to be expected on any of the automotive parts. Try to get something from cherry! Sandy >John is of course right but I got the impression from the data sheet that >the switch-mode usage was not reccomended - maybe because of the RFI >considerations. >The problem I have with using the LM1949 as a switch-mode controller is that >the zener has to dump a lot of power - this may be both more expensive and >more difficult to package than a design using the L584. >Lastly one should beware that NatSemi are pretty good at giving out samples >but when it comes to buying parts such as these (automotive special function) >they always quote me horrendously large minimum order quantities. Maybe this >is no worse than the SGS lead time? > >I am really interested to hear about the L9335/9336 chips - they sound like >the (near-)perfect solution. > > Regards, Martin Mayhead > ------------------------------ From: Bill Sarkozy Date: Tue, 27 Feb 1996 21:34:25 -0800 Subject: T-Coupe Intercooler Could anyone tell me where I can find a Thunderbird Turbo-Coupe Intercooler? Any and all information would be greatly appreciated. Thanks. Bill Sarkozy Kala mazoo, MI ------------------------------ From: robert dingli Date: Wed, 28 Feb 1996 14:08:52 +1100 (EST) Subject: Re: Thoughts on crank angle sensing Paul Campbell writes, ... > As for instantaneous acceleration, another op-amp circuit can do a high pass > filter on the PLL's output. From acceleration, we can also calculate > instantaneous torque. By looking for peaks in this signal (another PLL or > another derivative?), the position of maximum torque can be located. This is a little bit more complicated than it may appear. The instantaneous acceleration of your slotted wheel it only indirectly related to the torque output of the engine. With much less resolution (60 teeth) than you propose, I have struck crankshaft resonance, driveshaft and dynomometer characteristics which make the calculations more complicated. Single cylinder test engines give good results but in the real world, multiple cylinders and external loads are difficult to analyse. For reference try SAE 945017,950005,890885,890884,900487,890486 etc. It's a great idea though. Robert - -- Robert Dingli r.dingli@xxx.au Power and Control Systems (+613) 9344 7966 Thermodynamics Research Labs (+613) 9344 7712 University of Melbourne, AUSTRALIA ** he who dies with the most toys, wins ** ------------------------------ From: pjwales@xxx.net (Peter Wales) Date: Tue, 27 Feb 1996 23:27:40 -0500 Subject: Re: Thoughts on crank angle sensing >I've been thinking about high resolution crank angle sensors lately..what does >anyone think about the following ideas? > >First, I want to get away from doing all the work in the CPU (reducing load >on the CPU)..but, I still want a measurement of maximum torque angle, position, >and overall velocity. > >Position is simple..the usual missing pulse detector will pick it out. And >then position itself can be handled by cleaning up a high resolution crank >angle sensor (200+ teeth) and sending the pulse train to a counter..the >missing pulse detector triggers the reset. This provides an instantaneous >angle position by simply reading the counter. Yes, if you can get a 200 tooth wheel. > >To get to velocity, I think a better way to go is to feed the pulse train >into a simple phase locked loop circuit, which will calculate the derivative >AND have the advantage of cleaning noise off the signal by altering the >characteristics of the loop filter. This will also give average torque by >assuming the engine mass is constant. How about using a counter reset by every tooth. Then read the number and you have a count proportional to velocity. > >As for instantaneous acceleration, Subtract this reading from the last and get acceleration Phase lock loops are difficult to make reliable and keeping it digital keeps it simple. Peter Wales President Superchips Inc Chairman Superchips Ltd "Timing is everything" Superchips home page with all the answers http://www.superchips.com ------------------------------ From: dn Date: Tue, 27 Feb 96 20:42:36 MDT Subject: re: DIY injector driver Bohdan Bodnar writes: > Shucks, a *real* do-it-yourselfer will *design* his/her own injector driver > circuit! I thought about this and said, "hmmm... this IS interesting!" This is exactly what I been cookin' up, but using an analog approach. It is a simple matter to whip up a constant current source with an opamp and mosfet transistor, with a current feedback resistor much as you suggested in your digital approach. In this manner you can set up a hold current at whatever value you want. Where I have run into a snag is how to force the thing to just go into saturation for the initial time, say 1.5 mS, to slam the injector open, without adding a bunch of timers and comparators. I'd like to stick to analog circuitry for several reasons, including reliability, no EMI, fewer parts, etc. I figure a dual opamp and a few R's and C's should do it, say $3-$5 worth of parts and a square inch of PCB area. Beats hell out of 10 chips and a uP any day. Only penalty is a bit more power dissipation in the hold mode, due to operation in the linear region of the driver transistor, nothing a little heatsinking won't cure. Remember the KISS principle... regards dn - -- - --------------------------------------------------------------------- Darrell A. Norquay Internet: dn@xxx.ca Datalog Technology Inc. Bang: calgary!debug!dlogtech!darrell Calgary, Alberta, Canada Voice: +1 (403) 243-2220 Fax: +1 (403) 243-2872 @ + < __/ "Absolutum Obsoletum" - If it works, it's obsolete -------------------------------------------------------------------- ------------------------------ From: dn Date: Tue, 27 Feb 96 20:51:10 MDT Subject: Re: Injector driver chips? Where? Brad writes: > Its a new chip, I guess its the replacement of the 3484. There's a little > info on it at the Motorola site. For the full data sheets, you have to use > the Motorola fax service. Not that it really matters, as it won't be > available for quite some time. Plus, as someone else pointed out, it doesn't > appear to be the peak/hold circuit I was under the impression that it was. > If you want I can set up the data sheets for ftp. Yeah, I got the data sheet today via FaxBack, it's definitely not peak/hold. That's the problem with these nice special purpose chips, ya can't get the damn things for love nor money. That's why I'm taking the DIY approach... regards dn - -- - --------------------------------------------------------------------- Darrell A. Norquay Internet: dn@xxx.ca Datalog Technology Inc. Bang: calgary!debug!dlogtech!darrell Calgary, Alberta, Canada Voice: +1 (403) 243-2220 Fax: +1 (403) 243-2872 @ + < __/ "Absolutum Obsoletum" - If it works, it's obsolete -------------------------------------------------------------------- ------------------------------ From: arthurok@xxx.com (ARTHUR OKUN ) Date: Tue, 27 Feb 1996 20:35:38 -0800 Subject: Re: Thoughts on crank angle sensing thats similar to how a hard disk data seperator works, ------------------------------ From: "Paul E. Campbell" Date: Tue, 27 Feb 1996 23:47:47 -0500 (EST) Subject: Re: Thoughts on crank angle sensing > >I've been thinking about high resolution crank angle sensors lately..what does > >anyone think about the following ideas? > > > >First, I want to get away from doing all the work in the CPU (reducing load > >on the CPU)..but, I still want a measurement of maximum torque angle, position, > >and overall velocity. > > > >Position is simple..the usual missing pulse detector will pick it out. And > >then position itself can be handled by cleaning up a high resolution crank > >angle sensor (200+ teeth) and sending the pulse train to a counter..the > >missing pulse detector triggers the reset. This provides an instantaneous > >angle position by simply reading the counter. > > Yes, if you can get a 200 tooth wheel. I could make one on the milling machines here but I had a slightly different idea..why not use an optical sensor instead of a hall effect sensor? The only advantage of the hall effect sensor is that it is immune to dirt..but since this is experimental anyway, I think I can do a good enough job of either keeping it all clean or sealing it. Then just take a drill to your choice of metal or plastic disks and punch out the required holes. [Simple fast counter versions deleted] ------------------------------ From: Andrew Dalgleish Date: Wed, 28 Feb 96 18:16:00 S Subject: RE: Thoughts on crank angle sensing On Tuesday, 27 February 1996 23:27, owner-diy_efi-outgoing wrote: [snip] > How about using a counter reset by every tooth. Then read the number and you > have a count proportional to velocity. > > > > >As for instantaneous acceleration, > > Subtract this reading from the last and get acceleration > > Phase lock loops are difficult to make reliable and keeping it digital keeps > it simple. > > Peter Wales > President Superchips Inc > Chairman Superchips Ltd "Timing is everything" > Superchips home page with all the answers http://www.superchips.com > > What you are suggesting is a simple form of digital PLL (or is it frequency locked?) I used a latch->rom->latch to lock on to the data stream for a floppy disk interface about 10 years ago. The advantage of the all digital approach is you can do (simple) prediction as to when the next pulse will appear. (ie what comes after 5,4,3,...) You still have design problems, just different ones :-( Regards, Andrew Dalgleish Axon Research, Pty Ltd 6 Wallace Ave, Toorak, VIC 3142 AUSTRALIA Tel +61-3-9826-5538 Fax +61-3-9824-0083 ------------------------------ From: Mika.J.Tuominen@xxx.com Date: Wed, 28 Feb 96 10:18:03 +0200 Subject: Basics of the timing advance Hi you there! I have been thinking about the principles of ignition timing advance. I converted one timing diagram of mechanically adjusted distributor from= degree-based to time-based graph, and noticed it has a peak in advance just above idle speed. Obviously that is coming from 'two-phase' adjusting mechanics in the distributor. Now I'm wondering is that kind of behaviour needed or can I make it better if I make the advance to follow engine speed linearly. = One other thing has also popped up when I was thinking my engine = controller (at first only controlling ignition). Can I live with two pulses per cranksaft revolution to make a timing good enough. In 4-cylinder 4-stroke engine is needed two sparks per 360degs, so if I place my sensor to cranksaft for example 30 degrees before TDC I have enough time to calculate delay to correct spark time, and speed I can derive from the delay between two pulses. Worst problem which came into my mind is that can engine speed change so rapid that I can't trust to speed counted from 180 degrees period. Any info about teeths per round value in existing systems would be appreciated. Easy place to find many teeths is starting gear, but I liked to keep my CPU free for other jobs, than responding to interrupts. = Thanks in advance, :) Mika =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Mika J. Tuominen Internet: mitu@xxx.com Nokia Mobile Phones Ltd. Address: P.O.box 86, FIN-24101 Salo, Finland = ------------------------------ From: einarp@xxx.no (einarp) Date: Wed, 28 Feb 96 09:53:40 CET Subject: Weber Jon, I'm not sure on this, but was told by a usually reliable person that the different colors of the plastic connector part of the injector shows if it's a high or low resistance one. The body is arbitrarily painted (or not). I will do a flow measurement of mine before the engine goes in this summer to verify all 6 have the same flow. After that I will at least know the flow characteristics for mine. (Black bodies 16 ohm injectors). I would also like to use the resulting table to tell me the instantaneous fuel consumption of the engine. I also have some Bosch injectors in my junk box, and would like to point out that they _look_ very similar, but have other dimensions and construction below the solenoid housing. They will not fit in the manifold made for the Marelli injectors. So tell him not to buy any before having checked the fit. >Does anyone happen to know the scheme Weber uses to identify the various >characteristics of their injectors, specifically the injector capacity? He Beg steal or borrow a milliohmmeter. First check the soldering, especially the ones around and after the power drivers. This is a very common fault in older color TV sets. It's caused by the high current and fast rise time. The same conditions exist in injector and coil drivers. Typical for this kind of fault is intermittent and temperature dependent failures. Meaning works for X minutes, then out. >The second question concerns the diagnosis and repair of the P7 computer. >The suspected flaw at this point is a cracked motherboard or broken trace >but it shows no visible cracks. - -- einarp@xxx.no ( Maserati Biturbo Spyder ) ------------------------------ End of DIY_EFI Digest V1 #59 **************************** 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".