A better Spark Out circuit.
07-16-2009, 02:40 AM
#63
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I'm not an electrical engineer, but leave a conductive wire loose to short circuit whenever it feels happy to? No thank you.
Plus, it says desolder the jumpers, now that doesn't mean desolder only half of each jumper either.
I want Joe or Matt to chime in here before I wreck my MSPNP.
Plus, it says desolder the jumpers, now that doesn't mean desolder only half of each jumper either.
I want Joe or Matt to chime in here before I wreck my MSPNP.
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07-17-2009, 10:17 AM
#67
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DIY's instructions couldn't be simpler. desolder the two jumpers going to PAD1 and PAD3. do not remove them, just desolder them at that spot. insert the transistors, then solder the red jumpers back to the transistors in the correct spots per the instructions. the end. simple 5 minute fix.
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07-18-2009, 09:50 AM
#69
Boost Pope
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Hey, guys. I've been around on sporadically for the past few weeks, so I'm playing catchup on old posts.
Here is my observation of a stock 1.6 igniter & coils being driven by an EMU. Yellow is trigger volts from the EMU, blue is coil primary amps.
I haven't actually dissected the igniter to inspect it, but you can see why I have inferred that the input has a high capacitance.
I haven't actually dissected the igniter to inspect it, but you can see why I have inferred that the input has a high capacitance.
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07-18-2009, 12:10 PM
#70
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Ahhh, that's not load capacitance you see. If it were capacitive you wouldn't have a step up in the igniter input (yellow) voltage (at the start) because a capacitor would need a very large spike in current to do that.
The rising igniter drive voltage with increasing primary current that you see is probably due to a current sense resistor scheme in the igniter circuit. (Such an architecture in driving inductive loads is quite common) The scheme accomplishes 2 things - a current limit if dwell is too long, in order to protect the main igniter transistor, and a means for the ECU to be able to sense the primary current by looking at the igniter drive voltage. Presumably some factory ECUs can dynamically adjust dwell time vs. system voltage, akin to having long term fuel trims.
Nevertheless whatever drive circuit you have for the igniter input, it would have to be capable of delivering the max input voltage (top of yellow) and the input current at that point, at a dwell > max needed (iow reaches current limit). I noticed that if you have insufficient drive, the max current (i.e. current limit setpoint), goes down. In the thread where I described the COP measurements, I give these values - these values give you a maximum allowable pullup resistance for a given pullup voltage.
Clear?
The rising igniter drive voltage with increasing primary current that you see is probably due to a current sense resistor scheme in the igniter circuit. (Such an architecture in driving inductive loads is quite common) The scheme accomplishes 2 things - a current limit if dwell is too long, in order to protect the main igniter transistor, and a means for the ECU to be able to sense the primary current by looking at the igniter drive voltage. Presumably some factory ECUs can dynamically adjust dwell time vs. system voltage, akin to having long term fuel trims.
Nevertheless whatever drive circuit you have for the igniter input, it would have to be capable of delivering the max input voltage (top of yellow) and the input current at that point, at a dwell > max needed (iow reaches current limit). I noticed that if you have insufficient drive, the max current (i.e. current limit setpoint), goes down. In the thread where I described the COP measurements, I give these values - these values give you a maximum allowable pullup resistance for a given pullup voltage.
Clear?
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08-10-2009, 07:14 PM
#74
My Popping and fouling has gotten fairly severe lately and i've been intentionally not performing joe's better spark out circuit assuming it has been letting me know that something else is wrong. If this pop is actually what is causing my fouling, then I need to do it.
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08-11-2009, 01:46 AM
#75
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Do you have anymore issues with plugs fouling? I'm trying to figure out if this popping is what is fouling my plugs or the fuel (leak?) issue that is giving the plugs something to ignite...
My Popping and fouling has gotten fairly severe lately and i've been intentionally not performing joe's better spark out circuit assuming it has been letting me know that something else is wrong. If this pop is actually what is causing my fouling, then I need to do it.
My Popping and fouling has gotten fairly severe lately and i've been intentionally not performing joe's better spark out circuit assuming it has been letting me know that something else is wrong. If this pop is actually what is causing my fouling, then I need to do it.
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08-11-2009, 09:33 AM
#78
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Yeah, as designed, the rev 3.0 board does not accommodate any logic-level ignition outputs, and only one high-current ignition output. Remember, this thing was mostly conceived by guys with old V8 engines running distributors.
So the "traditional" two-channel ignition output (soldering the two resistors across the LEDs) is a mod, and then my circuit is a mod to a mod. The problem is that whoever came up with that mod in the first place (and it's been years, so who the heck knows where it originally came from) was either lazy, cheap, or just didn't take the time to really think about how the circuit was going to behave in-situ.
So the "traditional" two-channel ignition output (soldering the two resistors across the LEDs) is a mod, and then my circuit is a mod to a mod. The problem is that whoever came up with that mod in the first place (and it's been years, so who the heck knows where it originally came from) was either lazy, cheap, or just didn't take the time to really think about how the circuit was going to behave in-situ.
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08-11-2009, 10:57 AM
#79
No more popping nor fouling. Cold and hot starts are awesome now, given that I stop messing with Crank and ASE (which I messed with before because of the popping). But this is the final solution. The board design was just crappy and this is a much better output circuit.
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