Coil Dwell, I don't think its right causing weak spark.
#16
yes 60/8000 is 0.0075 seconds per rev and let me edit my other post i started to type to fast and inerchanged cycle and rev a few times and few incorrect times.
Last edited by Spaceball 1; Sep 11, 2008 at 04:20 PM.
#17
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AEM has always had messed up coil dwell settings.
A coil dwell factor setting of 35 means 3.5mS, the dwell vs RPM and dwell vs voltage tables are multiplier tables. So if your factor was 35, and both tables were a flat 100, your dwell time is fixed at 3.5mS.
dwell max of .5 tooth is retarded, it needs to be 1 to 1.25, bit SOME trigger setups cannot tolerate settings above 1 tooth. You theoretically have 2 teeth for charge and recovery, but the way they do their triggering won't let you use all of it.
A constant charge inductive coil with a system voltage (13-14v) dwell time requirement above 3.5-4ms is very rare. The factory coil driver IC inside the coil may or may not have a current (and/or temp) limiting driver (I doubt it does having seen some IC toasted coils), so be careful. The only way you're going to find out how far you can go is by lab scoping under your running conditions and finding out at what point you get full saturation. The variables are input voltage, temp. They SHOULD have a 2D table to vary dwell with load, as you don't need full saturation at all loads, it just overheats the coil driver IC and coil.
A high dwell inductive waste spark system is RPM limited, you'll run out of charge and recovery time somewhere between 8500-9500 RPM. True 4 channel inductives don't have this time limitation.
Info- The DSM ign transistor is a current limiting type, the most you will get out of it is 7A. The 85.5-90 RX7 ign module is a 9A current limiting module with very good coils. There are automotive inductive coil specific IGBT's (direct ECU trigger) available that are capable of anywhere between below 10A and above 30A per unit.
A coil dwell factor setting of 35 means 3.5mS, the dwell vs RPM and dwell vs voltage tables are multiplier tables. So if your factor was 35, and both tables were a flat 100, your dwell time is fixed at 3.5mS.
dwell max of .5 tooth is retarded, it needs to be 1 to 1.25, bit SOME trigger setups cannot tolerate settings above 1 tooth. You theoretically have 2 teeth for charge and recovery, but the way they do their triggering won't let you use all of it.
A constant charge inductive coil with a system voltage (13-14v) dwell time requirement above 3.5-4ms is very rare. The factory coil driver IC inside the coil may or may not have a current (and/or temp) limiting driver (I doubt it does having seen some IC toasted coils), so be careful. The only way you're going to find out how far you can go is by lab scoping under your running conditions and finding out at what point you get full saturation. The variables are input voltage, temp. They SHOULD have a 2D table to vary dwell with load, as you don't need full saturation at all loads, it just overheats the coil driver IC and coil.
A high dwell inductive waste spark system is RPM limited, you'll run out of charge and recovery time somewhere between 8500-9500 RPM. True 4 channel inductives don't have this time limitation.
Info- The DSM ign transistor is a current limiting type, the most you will get out of it is 7A. The 85.5-90 RX7 ign module is a 9A current limiting module with very good coils. There are automotive inductive coil specific IGBT's (direct ECU trigger) available that are capable of anywhere between below 10A and above 30A per unit.
#18
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AEM has always had messed up coil dwell settings.
A coil dwell factor setting of 35 means 3.5mS, the dwell vs RPM and dwell vs voltage tables are multiplier tables. So if your factor was 35, and both tables were a flat 100, your dwell time is fixed at 3.5mS.
dwell max of .5 tooth is retarded, it needs to be 1 to 1.25, bit SOME trigger setups cannot tolerate settings above 1 tooth. You theoretically have 2 teeth for charge and recovery, but the way they do their triggering won't let you use all of it.
A constant charge inductive coil with a system voltage (13-14v) dwell time requirement above 3.5-4ms is very rare. The factory coil driver IC inside the coil may or may not have a current (and/or temp) limiting driver (I doubt it does having seen some IC toasted coils), so be careful. The only way you're going to find out how far you can go is by lab scoping under your running conditions and finding out at what point you get full saturation. The variables are input voltage, temp. They SHOULD have a 2D table to vary dwell with load, as you don't need full saturation at all loads, it just overheats the coil driver IC and coil.
A high dwell inductive waste spark system is RPM limited, you'll run out of charge and recovery time somewhere between 8500-9500 RPM. True 4 channel inductives don't have this time limitation.
Info- The DSM ign transistor is a current limiting type, the most you will get out of it is 7A. The 85.5-90 RX7 ign module is a 9A current limiting module with very good coils. There are automotive inductive coil specific IGBT's (direct ECU trigger) available that are capable of anywhere between below 10A and above 30A per unit.
A coil dwell factor setting of 35 means 3.5mS, the dwell vs RPM and dwell vs voltage tables are multiplier tables. So if your factor was 35, and both tables were a flat 100, your dwell time is fixed at 3.5mS.
dwell max of .5 tooth is retarded, it needs to be 1 to 1.25, bit SOME trigger setups cannot tolerate settings above 1 tooth. You theoretically have 2 teeth for charge and recovery, but the way they do their triggering won't let you use all of it.
A constant charge inductive coil with a system voltage (13-14v) dwell time requirement above 3.5-4ms is very rare. The factory coil driver IC inside the coil may or may not have a current (and/or temp) limiting driver (I doubt it does having seen some IC toasted coils), so be careful. The only way you're going to find out how far you can go is by lab scoping under your running conditions and finding out at what point you get full saturation. The variables are input voltage, temp. They SHOULD have a 2D table to vary dwell with load, as you don't need full saturation at all loads, it just overheats the coil driver IC and coil.
A high dwell inductive waste spark system is RPM limited, you'll run out of charge and recovery time somewhere between 8500-9500 RPM. True 4 channel inductives don't have this time limitation.
Info- The DSM ign transistor is a current limiting type, the most you will get out of it is 7A. The 85.5-90 RX7 ign module is a 9A current limiting module with very good coils. There are automotive inductive coil specific IGBT's (direct ECU trigger) available that are capable of anywhere between below 10A and above 30A per unit.
The next question I don't get is why they have the Max Dwell set at 4 on the EVO 9 base cal, sounds like possible issues could happen. I am beginning to think AEM Goofed both the 8 and 9 Max Dwell Factors.
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Just got back from the dyno, had some slight misfires before.Today the only thing I changed was the Dwell Max to 1.0 tooth and Dwell Min to 0.1 tooth and had no problems @ the dyno. On the street I ran the car 1st thru 4th gear to +/- 135mph and no hiccups whatsoever.
#20
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I think we are onto some great findings here where the stock EVO coils can get some good use out of them.
Last edited by GTVEVO; Sep 12, 2008 at 07:30 AM.
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Spaceball 1 gave a good strategy, as for myself I am running a flat 105 with max dwell at 1.25. I would say somewhere in both of our areas is going to be a good reliable setting. My car needs and wants to rev past 8k so I am going to try to get everything I can out of it. I will probably end up backing it down in the lower rpm ranges just to ensure I don't build too much heat.
#24
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I personal don't think you need to mess with the dwell.. I had a simular situation with my coils on the stock computer. I replace spark plugs. that didn't work.. Gap them tighter.. Still didn't work.. Then I replace the coils and it went away. I'll bet that you just have a bad coil or the boots just arc-gaping on you.
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I personal don't think you need to mess with the dwell.. I had a simular situation with my coils on the stock computer. I replace spark plugs. that didn't work.. Gap them tighter.. Still didn't work.. Then I replace the coils and it went away. I'll bet that you just have a bad coil or the boots just arc-gaping on you.
Last edited by GTVEVO; Sep 13, 2008 at 04:01 PM.
#26
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I'd agree with you about open to learning something new. After reading the thread more i kinda jump on and posted not reading everything.. Sorry about that. So are you just experiencing miss fire and thats what make you believe the wizard isn't set up properly? I just have never had a miss fire and I'm still on stock coil on the AEM.. The only miss fire I was getting is tuning with Q16.. If you get lean the car just breaks up. Give it some fuel and it goes away. Thou in the wizard The 9's dwell vs RPM and Dwell vs battery is different then the 8's
Last edited by awdboosted; Sep 14, 2008 at 12:55 PM.
#27
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I'd agree with you about open to learning something new. After reading the thread more i kinda jump on and posted not reading everything.. Sorry about that. So are you just experiencing miss fire and thats what make you believe the wizard isn't set up properly? I just have never had a miss fire and I'm still on stock coil on the AEM.. The only miss fire I was getting is tuning with Q16.. If you get lean the car just breaks up. Give it some fuel and it goes away. Thou in the wizard The 9's dwell vs RPM and Dwell vs battery is different then the 8's
I never had any misfire issues on the stock ecu rich or lean and race or pump gas.
#28
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That may be another issue I've never had any misfires at 20psi. But like I said the there is no wizard for 9's but they are set up differently then the 8's That may be the case.
Also are you guys check your timing with a light gun when you are making the changes.. I was told you would need to by AEM..
Also are you guys check your timing with a light gun when you are making the changes.. I was told you would need to by AEM..
#29
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That may be another issue I've never had any misfires at 20psi. But like I said the there is no wizard for 9's but they are set up differently then the 8's That may be the case.
Also are you guys check your timing with a light gun when you are making the changes.. I was told you would need to by AEM..
Also are you guys check your timing with a light gun when you are making the changes.. I was told you would need to by AEM..
Yes I understand there is no wizard for the 9 but there is for the 8 and they make you assume that the wizards are there to give you accurate settings and in this case it does not. Next the base cal Dwell settings are different between the 8 and 9 and there is no reason they should be to my knowledge this is why I started questioning the difference. Also questioning the Max Dwell on the 9 because it is set to 100% or 4 teeth in the base cal file for the 9 which makes no sense at all and could potentially cause someone to over dwell/heat the coils. This is just one more example that shows the base cal files need to be looked at more closely in my opinion.
I have heard so many different stories about checking the timing with a gun it isn't even funny. Yes I checked my timing and it has been adjusted correctly but it has no impact to a coil dwell issue. If changing the coil dwell is causing the ignition timing to change I think we have a whole different issue happening but I have yet to see that on issue with my car. Thanks for the heads up though. Anytime I have called AEM......well..... I will leave it at that.
Last edited by GTVEVO; Sep 14, 2008 at 06:21 PM.
#30
I'd agree with you about open to learning something new. After reading the thread more i kinda jump on and posted not reading everything.. Sorry about that. So are you just experiencing miss fire and thats what make you believe the wizard isn't set up properly? I just have never had a miss fire and I'm still on stock coil on the AEM.. The only miss fire I was getting is tuning with Q16.. If you get lean the car just breaks up. Give it some fuel and it goes away. Thou in the wizard The 9's dwell vs RPM and Dwell vs battery is different then the 8's
Take a look at the 1st and 2nd gen coil dwells they are also way different than the evo 8 and 9.