DIY_EFI Digest Tuesday, 22 October 1996 Volume 01 : Number 321 In this issue: Re: RCA tuner fix. (VW EFI DIAGRAMS) Re: Tach input from spark voltage (idea) Re: Tach input from spark voltage (BEWARE!!!) Re: Tach input from spark voltage ** ERROR ** Re: RCA tuner fix. (VW EFI DIAGRAMS) Re: tach input Snap-On scanner E-prom Re: Snap-On scanner E-prom Re: Tach input from spark voltage (BEWARE!!!) GM NEG EGR Knock sensors 7 terminal HEI module 5 terminal HEI module Re: Knock sensors interfacing EGT sensor with O2 senor input Re: Harness Connector for Honda Civic re: Knock sensors Ignition List RE: tach input See the end of the digest for information on subscribing to the DIY_EFI or DIY_EFI-Digest mailing lists. ---------------------------------------------------------------------- From: Fredrik Skog Date: Mon, 21 Oct 1996 12:13:53 +0100 (MET) Subject: Re: RCA tuner fix. (VW EFI DIAGRAMS) Hello! You can try http://proffa.cc.tut.fi/~k124775/Injection.html Hope this helps! ############################################################################## Fredrik Skog '70 2002 ti O==00==O \\\ Amiga 1200 Email: c95fsg@xxx.se \\\ /// WWW: http://www.ts.umu.se/~skog/ \\X// On Mon, 21 Oct 1996, Craig Pugsley wrote: > > Hi Brad, the first place to start is Fil's electronics home page. He's got > > a lot of repair information, and lots of links to other pages. The URL is: > > > > http://www.paranoia.com/~filipg/ > > > > Everyone on this list could probably find something interesting at his > > site, give it a look. > > This guy said on sci.electronics a while ago that there were some > reverse engineered curcuits of VW L-Jet somewhere on the net.. > I tried emailing him (2-3 times) with no reply.. Anyone seen this stuff? > > Cheers, > Craig. > ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 21 Oct 1996 08:26:12 -0500 Subject: Re: Tach input from spark voltage (idea) > >I've been working on various inductive tach schemes with some success. I >want to try a new approach which would be to take the input to the tach >from the "points" or "tach" signal from a car distributor (or whatever). > >In case my description is lacking, from the input or low voltage side of >the coil (or cap or whatever). What voltage range should I expect this >signal to be in? Are we talking tens of volts or hundreds? > >I understand that the spark plug sees kV, but the input to the spark >circuit should be quite a bit lower, right? [ snip ] There will be several hundred volts at the primary of ALL ignition coils, regardless of what method they use. Without a complete rehash of inductance and L-C (tank) circuits, just experiment with a coil and a resistor. Get a starter solenoid (for starters, heh - heh). Measure its resistance. Now, get a resistor of the same value. Take some clip leads and connect the coil (starter solenoid) to the battery several times. Sparks, right??? Do the same thing with the resistor. If you see any sparks, they'll be LOTS smaller. Try holding the clip leads (that have the 12 volts from the battery) with each hand whilst you do this. The 12 volts won't hurt you. Touching the resistor whilst holding them won't hurt you. I can't say that you will feel anything doing this with the solenoid, but you might (depends on the amount of inductance). GUARANTEED: If you do the above experiment with an ignition coil, touching the primary only, you'll get a jolt. Wanna BIG jolt (I can personally attest to this 'learning from experience'). Put your hand on the output terminal of the ole starter solenoid whilst you're starting your car -- you're guaranteed a jolt stronger'n Chicory coffee in Reserve, LA. So. What's the answer? On points / coil ignition: +12 volts with points closed. Some large NEGATIVE (I usually estimate about - -300 volts) voltage when they open. This voltage will "ring" positive and negative and will "damp" (i.e. die down, just like a kid's swing when no one's pushing it). How fast it is damped depends on the circuit conditions: capacitance and load (spark plug). CDI systems skip the +12 volt step and just knock the snot out of it with the 300 volts from the git-go. So, if'n you want to read this signal, it's reasonably easy. That's what 'clamping' diodes are for (that's just a diode you use to 'clamp' sumpin'). Put a resistor in series with your pickup (maybe 100-k ), tie (clamp) the other side to something with two diodes. Example: to trigger a CMOS gate: put 100-k R in series. >From the gate input, put one diode with Anode connected to the supply, and the other with the Cathode connected to GND. I don't like to use any kind of MOS in an app like this. I prefer good old BJT (read: plain ole transistor) whenever there's large noise spikes (worst case: ignition pickup!!!!). So, I would drive a simple NPN transistor with the circuit described above (substitute the base of the transistor for the CMOS gate input). Bottom line: the noisiest signal you're going to have to deal with in a car: the ignition -- including (esp.) the primary. Second noisiest: the alternator. Actually, everything else is pretty quiet (except the starter). Tom Cloud ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 21 Oct 1996 08:41:35 -0500 Subject: Re: Tach input from spark voltage (BEWARE!!!) >I know that's what we were taught in school, but I have never been able to >"scope" anything near that high out of a simple points and coil system with >a cap to ground on each post of the coil. I also don't understand the line >below about the resister and zener bit. He wanted to use an inductive >pickup to sense the ignition on the primary side, not attach to it >directly. The spikes will be fast and severe -- but limited by the cap. The cap absorbs the energy of the coil temporarily, thereby extending the length of the spark -- and protecting the points from burning. Tom Cloud ------------------------------ From: cloud@xxx.edu (tom cloud) Date: Mon, 21 Oct 1996 11:44:08 -0500 Subject: Re: Tach input from spark voltage ** ERROR ** >> >>I've been working on various inductive tach schemes with some success. I >>want to try a new approach which would be to take the input to the tach >>from the "points" or "tach" signal from a car distributor (or whatever). ERROR: ***************** >Example: to trigger a CMOS gate: put 100-k R in series. >>From the gate input, put one diode with Anode connected to the supply, >and the other with the Cathode connected to GND. ERROR **** in the above ... I got it upside down. Switch "Anode" and "Cathode" above, elst you'll have a shorted supply!! [ snip da rest ] Tom Cloud ------------------------------ From: "Frank Sanford" Date: Mon, 21 Oct 1996 13:05:03 -0400 Subject: Re: RCA tuner fix. (VW EFI DIAGRAMS) >This guy said on sci.electronics a while ago that there were some >reverse engineered curcuits of VW L-Jet somewhere on the net.. >I tried emailing him (2-3 times) with no reply.. Anyone seen this stuff? > >Cheers, >Craig. Try this: http://proffa.cc.tut.fi/~k124775/Injection.html This puts you in the middle of his homepage, directly at the FI stuff. Hopefully this is the one you're looking for. It has L-jet signals at various locations on the boards the and circuits. Frank - -- Frank Sanford Email: fsanford@xxx.com Motorola, CIG Phone: (770) 333-2121 Suite 550 Fax: (770) 333-2142 2839 Paces Ferry Rd Atlanta, GA 30339 ------------------------------ From: Grant Beattie Date: Mon, 21 Oct 1996 11:34:13 -0600 (MDT) Subject: Re: tach input On Mon, 21 Oct 1996, Krister Wikstrom wrote: Some really great and helpful stuff, thanks. > I have used opto-isolator, and didn't have any problems. I found an > old 4N25 opto, put two resistors in series, and a zener diode from > between the resistors to the other side of the input diode - the first > resistor limits the current to the zener (I used 15V), and the next one > sets the max current to the opto input. I guess I was a little vague. The only peice of info I'm missing is what's the original input voltage? You have a 15v zener that limits the voltage excursions and an input resistor as well. So if the voltage on the zener is 15v, what's the voltage on the input res? Mystery input voltage R1 R2 0--------WWWW-----------WWWWW------ opto | | / --- / ^ Zener / \ --- | | === - GB ------------------------------ From: Karl Hafen Date: Mon, 21 Oct 1996 15:14:29 -0600 Subject: Snap-On scanner E-prom Hello I've been reading the list for a while now and, while it is a bit off the subject, I've got something I am curious about. We just bought the update pack for our Snap-On MT-2500 scanner. This consisted of two E-Proms. Pealing the labels off the old proms revealed the following markings. On the 28 pin: PGM=12.4v b9412al NMC27C64Q 200 On the 32 pin: M27C401 - -F1 V88AD 9348CS SINGAPORE My question is are these common parts that can be read with a prom reader and stored on disk, or are they proprietary Snap-on only units?? Thanks Karl Hafen khafen@xxx.net ------------------------------ From: Land Shark Date: Mon, 21 Oct 1996 16:39:42 -0600 Subject: Re: Snap-On scanner E-prom At 03:14 PM 10/21/96 -0600, you wrote: >NMC27C64Q Yup .. a National Semi 27C64Q eprom >M27C401 >-F1 Yup 27C401 .. probably Mitsu. Jim PS: My Dataman S4 will read them both ------------------------------ From: hoss karoly Date: Sun, 20 Oct 1996 07:15:31 +0200 Subject: Re: Tach input from spark voltage (BEWARE!!!) Johnny wrote: > > I know that's what we were taught in school, but I have never been able to > "scope" anything near that high out of a simple points and coil system with > a cap to ground on each post of the coil. I also don't understand the line > below about the resister and zener bit. He wanted to use an inductive > pickup to sense the ignition on the primary side, not attach to it > directly. > yeah I tend to believe what I was taught but if the cap dies the voltage can be really high I'd put an opto-coupler between my pic and the signs :) bye charley ------------------------------ From: Jennifer Rose Date: Mon, 21 Oct 1996 18:34:44 -0700 Subject: GM NEG EGR Hi George Not sure I can explain- according to my Camaro shop manual. With eng not running, apply vacuum to EGR valve. Start eng and observe vacuum. Valve is good if valve moves to seated position(valve closed) and vacuum dropped while starting engine. My valve works this way and earlier this year passed smog test here in California. Both pos/neg EGRs have an air bleed in primary diahram to meter flow. Hope this is helpful Vance ------------------------------ From: john spears Date: Mon, 21 Oct 96 20:31 EST Subject: Knock sensors I saw alot of discussion about knock and its relationship to A/F ratio. Although it's true that a lean mixture can lead to knock due to soaring combustion chamber temperatures, the primary reason for knock sensors is to correct for an over-advanced condition. After all when knock is detected, the spark is retarded, not the A/F richened. Just my .02 on the subject. John Spears Speartech Fuel Injection Systems ------------------------------ From: john spears Date: Mon, 21 Oct 96 21:25 EST Subject: 7 terminal HEI module dzorde asked about the 7 term HEI module. Yes this can easily be fitted to a variable reluctance distributor to set up the proper signals to and from the ECM. The BYPASS line is used to determine which is controlling when the coil fires; the HEI module or the ECM. When cranking, the HEI module is controlling the ign. coil and you are firing on base timing. When the ECM determines that the engine is running, (refered to as KRPMUP) it sends a signal down the bypass line (bypass goes high), at this point the ECM takes over the function of determining when to fire the coil. In other words when bypass is low, the ignition module controls spark, and when bypass goes high the ECM controls spark. The reference terminal is the squared rpm signal for the ECM (derived from the rotating reluctor) and the EST line is the actual coil firing command signal from the ECM. John Spears Speartech Fuel Injection Systems ------------------------------ From: john spears Date: Mon, 21 Oct 96 21:25 EST Subject: 5 terminal HEI module dzorde asks about the function of the 5 terminal HEI module. This was an early control system for knock control only. The distributor (dizzy?) still had centrifugal weights and a vacuum advance. The positive line of the two wire pickup coil is sent to an ESC controller, instead of going right to the HEI module as in the 4 terminal variety. If the ESC controller is not detecting any knock input it simply allows the pickup coil signal to return to the module and fire the coil. If it does detect knock, it DELAYS the return of the pickup coil signal for a time equal to the numbers of degrees of retard it commands, based on a lookup table in the ESC controller. The 5th terminal is simply used as the line to return the pickup coil signal on. It was an early, rather crude method of knock retard, but was perceived as a great accomplishment at the time. I make this assumption based on the size of the "ESC" emblem they used to put on the tailgate of trucks equipped with this system. When I am doing a repair on these systems, most customers allow me to just loop the positive pickup coil wire back into the module and throw the ESC controller away! John Spears Speartech Fuel Injection Systems ------------------------------ From: "John Faubion" Date: Mon, 21 Oct 1996 21:20:38 -0500 Subject: Re: Knock sensors > I saw alot of discussion about knock and its relationship to A/F ratio. > Although it's true that a lean mixture can lead to knock due to soaring > combustion chamber temperatures, the primary reason for knock sensors is to > correct for an over-advanced condition. After all when knock is detected, > the spark is retarded, not the A/F richened. Just my .02 on the subject. Well John since I can't adjust the timing on a race kart I have no choice but to adjust A/F ratio. Since this works though and since the O2 sensor doesn't do a great job under WOT conditions, I'm thinking this might be a decent way to adjust A/F for maximum power under WOT conditions. Using EFI on the street in a production type scenario is not necessarily what I have in mind. 8) John Faubion ------------------------------ From: Lawrence Ho Date: Mon, 21 Oct 1996 22:19:31 -0700 Subject: interfacing EGT sensor with O2 senor input Hi Johnny O2 sensor have two distinctive state rich 0.6 > 0.9v lean 0.1 > 0.4v How about using a micro controller or a Pic to monitor EGT. If you want more fuel just sent a sent a low voltage (0.1 > 0.4v) to the O2 sensor input, which tells the computer O2 sensor is lean and hence sent more fuel. When the EGT is in the desire range, just oscillate between lean and rich very fast or 0.5v ? Of course there will be a limit on how much the computer will compensate before thinking the sensor is not working or running out of block learn. Lawrence Ho Johnny Faubion wrote: > The main problem I had was getting the EGT sensors I have calibrated to > something useful for the O2 sensor input on the Haltech box. EGT is wide > scale, O2 sensor is narrow. The other issue was picking an EGT sensor that > I thought I could get in the future as this is to be a production engine. I > ended up doing a (gasp) simple OPamp circuit to do the conversion which was > not satisfactory because of the wide range of the EGT sensor and the > nonlinearity between the two scales. I think I need to go > analog->digital->analog to get enough control of what the output to the O2 > sensor input of the box is. ------------------------------ From: Lawrence Ho Date: Mon, 21 Oct 1996 22:40:06 -0700 Subject: Re: Harness Connector for Honda Civic Hi Anyone knows where I could find the connector that plugs into the ECU for Honda's. Perferably male and female. I want to make a controller that modify some of the fuel and igniton map. Similar to HKS's. My controller would be in series between the OEM ECU and the engine. I don't want to cut or modify the factory harness. Any suggestion. thanks Lawrence Ho ------------------------------ From: RABBITT_Andrew@xxx.au Date: Tue, 22 Oct 1996 13:34:26 est Subject: re: Knock sensors > After all when knock is detected, the spark is retarded, not the A/F > richened. richening the mixture is sometimes used (initially) before retarding spark in closed-loop ignition control because it suffers a lower loss of power. ($US0.015 more on the subject) ------------------------------ From: Mark Pitts Date: Tue, 22 Oct 1996 09:42:57 +-100 Subject: Ignition List OK guys, I got a lot of typing of names and addresses to do, please = could anybody else that wants to join put the address in the mail body, = as its hardwork reading through mail headers! Mark PS I expect to have the names in the list by the end of the night, then = it will be active. I will also post the list on: http://www.zymurgy.org/~saxon/ignition.list so if you dont seem to be getting mail, you can check to see if I made a = typo while entering your address. Mark. ------------------------------ From: Krister Wikstrom Date: Tue, 22 Oct 1996 11:23:43 +0200 Subject: RE: tach input - ------ =_NextPart_000_01BBC00B.7C5948E0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Like I said, I'm no expert on this, but: If there were no inductance in the coil, you'll get square wave of battery voltage. The lowest battery voltage sets the highest value for the resistors to give enough current for the opto. Let's say 9V - this leads to around 4k to give 2mA. Max. current for the opto then defines R2, 10mA gives around 1k, so R1 is around 3k. The inductance introduces large voltage spikes up to 300-400V, but this is no static state. If it was, R1 should dissipate 40W, but I guess .5W should be enough, at least I used .25W, and it don't warm up. Come to think of it, the voltage spike is negative?, and so the zener not actually required... Anyway it is there for safety. Some filtering is also required to smooth it up. - ---------- From: Grant Beattie Sent: Monday, October 21, 1996 19:34 To: Krister Wikstrom Cc: 'DIY_EFI' Subject: Re: tach input I guess I was a little vague. The only peice of info I'm missing is what's the original input voltage? You have a 15v zener that limits the voltage excursions and an input resistor as well. So if the voltage on the zener is 15v, what's the voltage on the input res? 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