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  • Originally posted by Joe Bialy
    This mod will save lots of people lots of money. It is also a good basis for real ignition upgrades.

    After 173,000 miles, my ignitor finally bit the dust. Not wanting to spend $224 for another one, or an equal amount for a feeble MSD, I wired in a $20 (Wells #DR-100) generic GM 4-pin HEI module instead.

    In a nutshell:

    The ECU's trigger output wire (BL/O) feeds the HEI's pin 'G'.
    Ground the HEI's pin 'W'.
    Ground the HEI's base.
    HEI's pin 'B' taps into the +12V dizzy feed wire (BK/P).
    HEI's pin 'C' taps into the coil's primary wire (Y/G).
    Remove the internal strap connecting the old ignitor to the coil plug center terminal.

    I mounted the HEI module on a bracket next to the LH headlamp.

    If $20 is too steep, head to the wreckers and get a used module for a buck or two. Almost every GM car from the mid 70's to the mid 80's has one.

    If you don't want the stock coil, it would be just as simple to use an external coil if you add the extra terminal to the cap for it. Lotsa places have hi-perf. HEI modules and HEI specific hi-perf. coils too.

    I have this mod mostly installed but I found a website that makes it look like the voltage the HEI was designed for may be less than the voltage the probe disty puts out (http://jaguar.professional.org/ignition/).

    I am concerned about hooking pin G of the HEI module up to my Disty Ignition Input because the voltage requirement for the HEI may be different from the disty. I have two questions and would really appreciate an answer from anyone who has measured this voltage or has printed material/website that provides answers.

    How much voltage does the reluctor in the original GM disty apply to pin G of the HEI module? In other words, what voltage was pin G of the HEI designed to take?
    Has anyone put a resistor in series with the Disty Ignition Input to step the 12v, found in a Probe, down to the voltage the HEI was designed for (if it's lower)?

    Comment


    • Originally posted by Jim48
      I have this mod mostly installed but I found a website that makes it look like the voltage the HEI was designed for may be less than the voltage the probe disty puts out (http://jaguar.professional.org/ignition/).

      I am concerned about hooking pin G of the HEI module up to my Disty Ignition Input because the voltage requirement for the HEI may be different from the disty. I have two questions and would really appreciate an answer from anyone who has measured this voltage or has printed material/website that provides answers.

      How much voltage does the reluctor in the original GM disty apply to pin G of the HEI module? In other words, what voltage was pin G of the HEI designed to take?
      Has anyone put a resistor in series with the Disty Ignition Input to step the 12v, found in a Probe, down to the voltage the HEI was designed for (if it's lower)?
      The reluctor in a GM disty is speed sensitive. At cranking speed, it'll put out a very very low voltage, maybe a tenth of a volt or so. At 6,000 rpm, it could put out as much as 30 or 40 volts. The HEI module accepts all of that painlessly and plucks out the negative going zero crossing to fire from.

      The nice uniform 5 volt pulses from the Probe's ECU is a walk in the park for it.

      Comment


      • Originally posted by Joe Bialy
        The reluctor in a GM disty is speed sensitive. At cranking speed, it'll put out a very very low voltage, maybe a tenth of a volt or so. At 6,000 rpm, it could put out as much as 30 or 40 volts. The HEI module accepts all of that painlessly and plucks out the negative going zero crossing to fire from.

        The nice uniform 5 volt pulses from the Probe's ECU is a walk in the park for it.

        Joe i really would like your advice on the IGBT`s
        i`m considering using.. ive found a couple of suppliers that do 5V gate IGBTs in either TO220 or 247 case styles.. it would be good to be able to replace the stock item and retain the ignitor dont you think?

        look here:
        http://www.incony.org/KLZEWiki/pwp_1...Page&iPage=HEI
        Last edited by Bluexcell; October 7, 2004, 03:02 PM.

        Comment


        • Originally posted by Bluexcell
          Joe i really would like your advice on the IGBT`s
          i`m considering using.. ive found a couple of suppliers that do 5V gate IGBTs in either TO220 or 247 case styles.. it would be good to be able to replace the stock item and retain the ignitor dont you think?

          look here:
          http://www.incony.org/KLZEWiki/pwp_1...Page&iPage=HEI
          Sure, an IGBT is at the heart of most ignitions. Look at the STI #VB921ZVFI. It appears to be the whole thing, more or less. for the masses though, it'll be hard to beat the simplicity of that ubiquitous HEI.

          In that February snow storm, I didn't have much time to fool around with this and I didn't have a stockpile of transistors to experiment with. I knew the HEI could drive that coil reliably and went with it. In the workshop, with more time and more flexibilty to experiment I would have just replaced that output driver because they're only $2.00, not $20.00!

          I also thought about building the complete HEI. The MC3444 chip is the logic behind it and the circuit is readily available. This way I could have tailored the coil current and dwell to perfection, but it doesn't really matter all that much.

          How are you going to dissect that old module to add the new driver?

          Comment


          • I have 5 of the Fairchild IGBT`s coming FOC as samples in a TO220 case style.. The existing device appears to be micro spot welded which i cant repeat, i took off the heat sink to have a look.. and there isnt much thermal contact paste under the device, i know it doesnt need much but it sure looks miserly.
            I`m just going to cut the pins close to the device, and solder the new one in. its ok from a thermal point of view, the device will never get hot enough to melt solder.. hell thats 300 degrees.. there is a vibration question though, but with the device securely clamped, and the pins immovable i think it will work just fine.. when ive got the new device my plan is to set up a simple freq generator to feed it like an NE555 and a scrapyard HT coil and run one for a day flat out into a plug... if that works ok.. then i will have confidence in it.. i could always put a a 250ma fuse in line with the ECU trigger circuit and a 6V Zener to protect the ECU in case of catastrophic failure, but i think thats overkill.
            looking at the device you suggest its only rated at 7.0 Amps..and 340V, the fairchild device is 20A at 400V.. better head room.

            Comment


            • Originally posted by Bluexcell
              I have 5 of the Fairchild IGBT`s coming FOC as samples in a TO220 case style.. The existing device appears to be micro spot welded which i cant repeat, i took off the heat sink to have a look.. and there isnt much thermal contact paste under the device, i know it doesnt need much but it sure looks miserly.
              I`m just going to cut the pins close to the device, and solder the new one in. its ok from a thermal point of view, the device will never get hot enough to melt solder.. hell thats 300 degrees.. there is a vibration question though, but with the device securely clamped, and the pins immovable i think it will work just fine.. when ive got the new device my plan is to set up a simple freq generator to feed it like an NE555 and a scrapyard HT coil and run one for a day flat out into a plug... if that works ok.. then i will have confidence in it.. i could always put a a 250ma fuse in line with the ECU trigger circuit and a 6V Zener to protect the ECU in case of catastrophic failure, but i think thats overkill.
              looking at the device you suggest its only rated at 7.0 Amps..and 340V, the fairchild device is 20A at 400V.. better head room.
              I would not feed the ECU directly into that coil driver transistor. One catasptophic failure of that driver could take out the zener and the ECU long before any protective fuse would ever know what hit it. Fuses are way too slow and would only blow long after the delicate components around it are already dead. A sacrificial $0.10 interface transistor, like the original ingnitor has could save an expensive ECU.

              Comment


              • Joe.. the circuit diagram shows that IGBT being driven directly from the ECU logic signal, and the fairchild, SGS and International Rectifier parts are all designed to run that way.. ive looked at the application notes.there isnt any other IC or circuit needed to drive the IGBT. if you using a power mosfet.. yes i can see that.. but the info on the IGBT`s shows they are clamped.. i think if i was that paranoid i would use a high speed opto anyway..

                Quote from the fairchild data sheet:
                General Description
                The ISL9V5036S3S, ISL9V5036P3, and ISL9V5036S3 are the next
                generation IGBTs that offer outstanding SCIS capability in the D² -
                Pak (TO-263) and TO-220 plastic package. These devices are
                intended for use in automotive ignition circuits, specifically as coil
                drivers. Internal diodes provide voltage clamping without the need
                for external components
                .

                Features
                • Industry Standard D-Pak package
                • SCIS Energy = 500mJ at TJ = 25oC
                • Logic Level Gate Drive

                BVCER Collector to Emitter Breakdown Voltage (IC = 1 mA) 390 V
                BVECS Emitter to Collector Voltage - Reverse Battery Condition (IC = 10 mA) 24 V
                ESCIS25 At Starting TJ = 25°C, ISCIS = 38.5A, L = 670 µHy 500 mJ
                ESCIS150 At Starting TJ = 150°C, ISCIS = 30A, L = 670 µHy 300 mJ
                IC25 Collector Current Continuous, At TC = 25°C, See Fig 9 46 A
                IC110 Collector Current Continuous, At TC = 110°C, See Fig 9 31 A
                VGEM Gate to Emitter Voltage Continuous ±10 V
                PD Power Dissipation Total TC = 25°C 250 W
                Power Dissipation Derating TC > 25°C 1.67 W/°C
                TJ Operating Junction Temperature Range -40 to 175 °C
                TSTG Storage Junction Temperature Range -40 to 175 °C
                TL Max Lead Temp for Soldering (Leads at 1.6mm from Case for 10s) 300 °C
                Tpkg Max Lead Temp for Soldering (Package Body for 10s) 260 °C
                ESD Electrostatic Discharge Voltage at 100pF, 1500Ω 4 kV
                ISL9V5036S3S / ISL9V5036P3 / ISL9V5036S3
                EcoSPARKTM 500mJ, 360V, N-Channel Ignition IGBT
                General Description
                The ISL9V5036S3S, ISL9V5036P3, and ISL9V5036S3 are the next
                generation IGBTs that offer outstanding SCIS capability in the D² -
                Pak (TO-263) and TO-220 plastic package. These devices are
                intended for use in automotive ignition circuits, specifically as coil
                drivers. Internal diodes provide voltage clamping without the need
                for external components.

                EcoSPARKâ„¢ devices can be custom made to specific clamp
                voltages. Contact your nearest Fairchild sales office for more
                information.
                Formerly Developmental Type 49443
                Applications
                • Automotive Ignition Coil Driver Circuits
                • Coil- On Plug Applications
                Features
                • Industry Standard D-Pak package
                • SCIS Energy = 500mJ at TJ = 25oC
                • Logic Level Gate Drive

                From On Semiconductor:

                Features
                • Ideal for Coil−on−Plug and Driver−on−Coil Applications
                • Gate−Emitter ESD Protection
                • Temperature Compensated Gate−Collector Voltage Clamp Limits
                Stress Applied to Load
                • Integrated ESD Diode Protection
                • Low Threshold Voltage for Interfacing Power Loads to Logic or
                Microprocessor Devices

                • Low Saturation Voltage
                • High Pulsed Current Capability
                • Optional Gate Resistor (RG) and Gate−Emitter Resistor (RGE)
                Applications
                • Ignition Systems
                Ignition IGBT
                20 A, 350 V, N−Channel D2PAK
                VCE(on) = 1.3 V @
                IC = 10 A, VGE  4.5 V
                This Logic Level Insulated Gate Bipolar Transistor (IGBT) features
                monolithic circuitry integrating ESD and Over−Voltage clamped
                protection for use in inductive coil drivers applications. Primary uses
                include Ignition, Direct Fuel Injection, or wherever high voltage and
                high current switching is required.


                i`m happy with that..
                Last edited by Bluexcell; October 8, 2004, 05:02 PM.

                Comment


                • Originally posted by Bluexcell
                  i think if i was that paranoid i would use a high speed opto anyway..

                  i`m happy with that..
                  It s not paranoia, its looking at every common failure mode and protecting against it. A cheap emitter follower ahead of that IGBT could save the ECU IF the ESD protection craps out. One spark from an open secondary ignition coil could do that. If the ESD doesn't crap out you'll be fine. If it does fail, you could end up scrambling for ECU parts from the roadside in a dead car.

                  My approach would be to relocate the unit away from the distributor and pretty much build it like the original ignitor except use one of those freebie IGBT's. You eliminate the heat soak issue, the ECU will never know its driving something different, and if it does die, you won't take anything else out with it. But, if you're happy doing it bare bones, go for it! On paper its fine.

                  Comment


                  • I used the internal resistor

                    Originally posted by Joe Bialy
                    You only need an external resistor if you use an external coil.
                    I have a '95 model GT. I installed your igniter mod using a DR-400 from a 1980 Caprice and an old fashioned, oil filled, cylindrical, external coil from an early '80's Chevy pickup. I just got it running this evening and it works great. I don't think the integral coil in the original distributor was hot enough because, with this external coil, the engine runs much smoother. We took it out and drove it at 5,000 RPM and it performed great.

                    I did one thing different than your 2/17/04 sketch. I used the internal 1K ohm resistor in the disty instead of adding a new one. The advantage is a cleaner installation with no resistor soldered into the tack wire. Here is the way I hooked it up:
                    Instead of cutting all three wires to the C-170 connector on the disty, I left the 731 wire on pin 3 (Tachometer Output) connected to the harness. I then connected pin 2 of the C-170 connector to pin C on the HEI module. This effectively puts the disty internal resistor in series with the tach output. In order to make this work there is one more thing you have to do - You have to cut the ICM ground wire on pin 5 of the C-134 disty connector. If you don't cut this ground wire pin C on the HEI remains grounded all the time and there is no spark.

                    Comment


                    • I had the same problem.

                      Originally posted by MAD MARK
                      I did all the wiring and check everything over a bunch of times and still can not get any spark. I bought the GP EL102 cause thats what Adavance had.

                      Ive even opened up the cap and redid everything in there a couple of times to no effect. The engine will turn but no spark is coming from the wires. What should I be checking?
                      When I first tried this I didn't cut the strap out of the disty, I yanked it out. I didn't realize I still needed the center connection without the strap. I had to solder the connector back on and it started right up. Below is a link to an image with some additional info. I hope this helps.

                      Strap Image
                      Last edited by rwilliamson; December 20, 2004, 08:08 AM.

                      Comment


                      • Niehoff DR400 and stock coil?

                        Will this work with the stock coil? Or will the HEI kill the coil? I attempted this a month ago on my sister's '95 and it ran for one day with the new HEI in it. Then she took it into her mechanic, and they told her the spark was too weak, so she had a rebuilt disty put in. I tested her coil, and the resistance was perfect according to the service manual.

                        Now my ignitor is gone on my 93. I would like to be able to do the coil later in the spring, when I can order the modified cap.

                        I am wondering after reading this note from Joe earlier in this thread:

                        "You are limited by both the coil and the module. Coil efficiency is always high for any modern coil, but its inductance is what will hurt you."

                        Am I going to run into this problem as well? Can the stock coil live with the DR400?
                        The key to your sexual ignition is not between your legs, it's inside your head. The brain is man's biggest sex organ, sending nerve impulses running down the spinal cord to trigger an erection. Keep in mind though that since arousal is an electrical spark travelling the neural motorway it can be dulled by a repetitive commute. So vary your starting procedure, explore side roads, stop at a roadside service area, let your partner drive, or, when applicable, road-test a new model.

                        Comment


                        • Originally posted by bhodgins
                          Will this work with the stock coil? Or will the HEI kill the coil? I attempted this a month ago on my sister's '95 and it ran for one day with the new HEI in it. Then she took it into her mechanic, and they told her the spark was too weak, so she had a rebuilt disty put in. I tested her coil, and the resistance was perfect according to the service manual.

                          Now my ignitor is gone on my 93. I would like to be able to do the coil later in the spring, when I can order the modified cap.

                          I am wondering after reading this note from Joe earlier in this thread:

                          "You are limited by both the coil and the module. Coil efficiency is always high for any modern coil, but its inductance is what will hurt you."

                          Am I going to run into this problem as well? Can the stock coil live with the DR400?
                          Inductance relates to how quickly the coil can accept charging current. Fast charging provides better spark at high RPM's. High inductance means that it will take longer for the coil to charge limiting its performance at high RPM.
                          So low inductance is better. Inductance is roughly proportional to resistance, so we want a low ohms coil. HEI is meant for a 0.4 ohm coil, the Probe's is 1.0 ohms. Not the best performing coil for higher RPM's, but it works.

                          Spark energy is related to how much current the coil can accept. The HEI module has an internal current limiting feature built into it. The stock modules limit coil current to around 4 amps or so, aftermarket jobbies maybe limit at 7 or 8 or even more amps. Higher current = fatter spark, so for highest performance we'd want maximum current.

                          With the current limiting in a stock module, the coil is protected from burning up because you can't pump more than 4 amps through it. AFAIK, the stock Probe ignitor does not have that feature.

                          If you buy a modified cap you'll want to buy a hot HEI module and its matching HEI coil. You'll get far more spark than any V-6 can handle.

                          Measuring a coil's resistance doesn't tell how well it is working. Just one shorted turn in that coil will severely hurt it and is undetectable with an ohmmeter. Its the difference between 1.000 and 1.01 ohms.

                          Comment


                          • am I missing something????

                            Joe,

                            When I hooked the DR400 into my distributor this evening, I got no spark at all. I had a probe hooked up to the battery positive, and the -IG on the diag connector. It was on steady, then flickered when I cranked it over. I had remembered to clip the strap going to the old ignitor.

                            Then I took a working distributor out of a working '93 MX-6, and put the clipped band in this one. The car fired up, although one of the guys pulled a wire and said the spark looked weak.

                            If the band inside the distributor is clipped, there is no way it was using the internal ignitor is there? I am trying to narrow down what is the problem. If that is the case then it all seems to point to the cap, rotor, or coil.

                            This all started when I had my fuel pump changed, before the pump went the car ran fine. The old pump was a crappy Canadian Tire no-name brand with a low LPH output. The new one is a Walbro 190. Could it be that I had a weak coil all along, and now the higher fuel pressure proved to be too much for it?

                            Any help is appreciated. It is nasty cold up here....

                            Cheers,

                            Brad
                            The key to your sexual ignition is not between your legs, it's inside your head. The brain is man's biggest sex organ, sending nerve impulses running down the spinal cord to trigger an erection. Keep in mind though that since arousal is an electrical spark travelling the neural motorway it can be dulled by a repetitive commute. So vary your starting procedure, explore side roads, stop at a roadside service area, let your partner drive, or, when applicable, road-test a new model.

                            Comment


                            • The HEI is trying to work if the probe flickered when you cranked. If the coil/rotor/cap is bad you wouldn't get a spark though.

                              There is no relationship between coils and fuel pumps at all.

                              Comment


                              • Originally posted by TheDestineCurse
                                How important is it to bolt the hei down to metal . . . I had a solid ground but nothing to bold it with. The result of course was no spark. and my gasket for my distributor cap flaked apart when I took it apart, could that posibly interfear with this from working? I think that It probly wouldnt... and another thing is will the car start without the mass airflow pluged in, I had to remove alot of the air intake to make things easyer....
                                If it is correctly grounded (W pin as well as module ground) and it doesn't get too warm it won't need to be mounted to metal. Mine never got very warm ever at all, it would have worked fine just hanging by the wires.

                                The most important part is the two ground terminations- W and module.

                                Comment

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