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Coil Dwell Disassem and Denso Coil Behavior

 
Old Apr 4, 2016, 02:38 AM
  #46  
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88580014

PHP Code:
  scaling name="CoilDwellTime" units="ms" toexpr="x*0.064" frexpr="x/0.064" format="%.2f" min="0" max="16.32" inc="0.064" storagetype="uint8" endian="big"/>
  
scaling name="CoilDwellTimeUpperBoundPercent" units="% of Eng Revolution Time" toexpr="100*x/256" frexpr="256*x/100" format="%.1f" min="0" max="100" inc="1" storagetype="uint8" endian="big"/>
  
scaling name="Percent256-8" units="%" toexpr="100*x/256" frexpr="256*x/100" format="%.2f" min="0" max="99.609375" inc="0.00390625" storagetype="uint8" endian="big"/>
  
scaling name="RPMInverse-16" units="RPM" toexpr="7500000/x" frexpr="7500000/x" format="%.0f" min="0" max="10000" inc="60" storagetype="uint16" endian="big"/>
  
scaling name="Percent128" units="%" toexpr="x/1.28" frexpr="x*1.28" format="%.0f" min="0" max="100" inc="1" storagetype="uint8" endian="big"/>

  
  
  <
table name="Ign Coil Base Dwell-Time" category="Ignition - Coil Dwell" address="3cc6" type="2D" level="2" scaling="CoilDwellTime">
  <
table name="Battery" address="6f14" type="Y Axis" elements="9" scaling="BatteryVoltage"/>
  </
table>

  <
table name="Ign Coil Dwell-Time Reduction Start RPM" category="Ignition - Coil Dwell" address="1346" type="1D" level="2" scaling="RPMInverse-16"/>

  <
table name="Ign Coil Dwell-Time RPM Reduction Factor" category="Ignition - Coil Dwell" address="3cd6" type="2D" level="2" scaling="Percent256-8">
  <
table name="Battery" address="6f14" type="Y Axis" elements="9" scaling="BatteryVoltage"/>
  </
table>

  <
table name="Ign Coil Dwell-Time Upper Bound" category="Ignition - Coil Dwell" address="3ce6" type="2D" level="2" scaling="CoilDwellTimeUpperBoundPercent">
  <
table name="Battery" address="6f14" type="Y Axis" elements="9" scaling="BatteryVoltage"/>
  </
table>
  
   <
table name="Ignition Coil, Dwell Time Correction 2" category="Ignition - Coil Dwell" address="3ce6" type="2D" level="2" scaling="Percent128">
 <
table name="Battery" address="6f14" type="Y Axis" elements="9" scaling="BatteryVoltage"/>
 </
table

Last edited by conroe; Apr 4, 2016 at 10:34 AM.
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Old Sep 29, 2016, 08:27 AM
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Originally Posted by mrfred View Post
Thanks for doing 9417. A heavier gauge wiring solution would be a nice feature, but its not absolutely necessary. For the rpm range we run, the main issue with stock wiring is that it might get a bit warm, or even hot. A heavier gauge solution would eliminate this issue. Coil output would be the same either way as long as the dwell was increased for the stock wiring as noted in one of my earlier posts.
Mr Fred, you bring up an interesting point. I'm troubleshooting an ignition issue that only shows up once the car is fully warmed up and been driving for a while. Until that point, everything runs flawlessly. When it acts up, the car sputters all through the rpm range and is extremely sluggish. I can smell gas and it seems to be a cylinder mis-fire or no-fire.

My car was tuned on stock coils and a few months ago I upgraded to the Denso COP and haven't touched the tune. My plugs are stock and all gapped at .020" Should I start with increasing the dwell time slightly as you've mentioned in this thread? Do you have any other suggestions? Thanks.
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Old Sep 29, 2016, 09:26 AM
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Originally Posted by Hookah Bazooka View Post
Mr Fred, you bring up an interesting point. I'm troubleshooting an ignition issue that only shows up once the car is fully warmed up and been driving for a while. Until that point, everything runs flawlessly. When it acts up, the car sputters all through the rpm range and is extremely sluggish. I can smell gas and it seems to be a cylinder mis-fire or no-fire.

My car was tuned on stock coils and a few months ago I upgraded to the Denso COP and haven't touched the tune. My plugs are stock and all gapped at .020" Should I start with increasing the dwell time slightly as you've mentioned in this thread? Do you have any other suggestions? Thanks.
The fact that you are seeing issues across the rpm range suggests to me that additional dwell is not needed. Also, these Denso COPs function just fine on the stock dwell settings. So there seems to be an issue unique to your Evo. Assuming your Evo is not a rustbucket from the saltbelt where there is likely to be a greater chance of grounding issues, my first thought is that one of your Denso coils has gone bad. My suggestion would be to purchase a replacement coil and swap it out with the existing ones on a one-by-one basis. If no issues there, then my suggestion would be to trace down the coil power wiring and look for possible grounding issues or other oddities with the wiring.
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Old Sep 29, 2016, 10:08 AM
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Originally Posted by mrfred View Post
The fact that you are seeing issues across the rpm range suggests to me that additional dwell is not needed. Also, these Denso COPs function just fine on the stock dwell settings. So there seems to be an issue unique to your Evo. Assuming your Evo is not a rustbucket from the saltbelt where there is likely to be a greater chance of grounding issues, my first thought is that one of your Denso coils has gone bad. My suggestion would be to purchase a replacement coil and swap it out with the existing ones on a one-by-one basis. If no issues there, then my suggestion would be to trace down the coil power wiring and look for possible grounding issues or other oddities with the wiring.
It's been in the southeast it's whole life, so no corrosion issues there. I've got another coil on the way to test with. Thanks for the input
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Old Feb 23, 2017, 11:05 AM
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the two cranking variables are defined to be the first cell in each table, or the 9.38v cell.
is that cell actually chosen exclusively during cranking or is the definition assuming 9.38v during cranking?
i replaced a dying little tiny battery with a good larger one and it messed up my cranking dwell pretty bad. im using d585 coils which auto-fire if they dwell too long so its advancing my timing and kicking back on my starter.

any help is appreciated.
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Old Feb 26, 2017, 04:23 PM
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The dwell variables are selected based on the actual voltage during cranking. You can log battery voltage using Evoscan if you want to see what it is.
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Old Aug 20, 2018, 05:38 PM
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Bringing this back.
I have D585 coils (
) on my mivec motor and those coils seem to be eroding the little electrode on the spark plugs pretty rapidly.
is there a way or a code tweak that could allow an rpm or load based dwell adjustment? I think if i can run less dwell at idle and cruise it will help my plugs last longer.
right now i planned to regap the plugs at every oil change, but they dont seem to be lasting that long.
i checked the units on the rpm dwell reduction and it doesnt support going negative allowing me to add dwell with rpm.
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Old Aug 24, 2018, 08:45 AM
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Originally Posted by mrfred View Post
cdi systems work differently, so none of this discussion applies.

i grew up in socal - still learning to appreciate the rain... we should meet up sometime.
Hello,

May I know how does these values applies to a CDI system?
I have AEM pencil Coils and the DYNATEC CDI box.
Values like the excel chart that you have provided would be very helpful

Thank you
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Old Oct 27, 2018, 01:50 PM
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Originally Posted by bu3_bu3 View Post
Hello,

May I know how does these values applies to a CDI system?
I have AEM pencil Coils and the DYNATEC CDI box.
Values like the excel chart that you have provided would be very helpful

Thank you
Capacitor Discharge Ignition (CDI) systems don't usually require a dwell time. The capacitors charge up very quickly and only require a trigger signal to fire them. For this reason it really doesn't matter if it's 1ms or 2ms or 3ms because the coil isn't being charged like in a regular inductive ignition system. It's being blasted by 500 volts on the primary winding which gives you a very intense high voltage output on the secondary and a big fat spark.

Setting the dwell to zero also won't work as there will be no trigger signal sent to the CDI unit. Try setting Base Dwell Time Table to 2 ms across the board and that should get you in the ball park. Let us know how it goes.

Last edited by cdrinkh2o; Oct 27, 2018 at 01:55 PM.
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