high rpm miss

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chilly
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high rpm miss

Post by chilly »

I have a High rpm miss/ backfire thru exhaust. Procharged Sbc 14lbs, 60-2 crank wheel with hall sensor and vortec distributor for the cam signal, cnp with truck coils, ms3 pro. Car runs and drives ok, just above 5000 rpm it acts up. I have been pulling fuel away from it and am at about 11.5 afr with no difference. I recorded a composite and tooth log but i really don't know what to make of it. Any help would appreciated, thank you.
billr
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Re: high rpm miss

Post by billr »

Also post MSQ and MSL
chilly
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Re: high rpm miss

Post by chilly »

ok current msl and msq
billr
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Re: high rpm miss

Post by billr »

What kind of "truck coils", the ones that auto-fire early when dwell gets up to about 4.5msec?
chilly
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Re: high rpm miss

Post by chilly »

yes the d585, i have tried several dwell settings and a second set of coils without any difference.
nathaninwa
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Re: high rpm miss

Post by nathaninwa »

What dwell settings have you tried?
Volvo 940, 2jzge, MS3Pro, daily
240Z, 2JZ, MS3Pro boost control
chilly
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Re: high rpm miss

Post by chilly »

from 3 to 4.5 ms
chilly
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Re: high rpm miss

Post by chilly »

If someone could read or explain what i am looking at on the composite log that would be appreciated, I at am at a loss as to what is causing this, fuel or ignition,, thank you.
grom_e30
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Re: high rpm miss

Post by grom_e30 »

comp log does not show any problems
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
chilly
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Re: high rpm miss

Post by chilly »

thank you very much.
grom_e30
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Re: high rpm miss

Post by grom_e30 »

for your ref if there is a problem with the signal there will be red marks along the bottom of the comp log to indicate sync was lost
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
chilly
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Re: high rpm miss

Post by chilly »

its never had sync issues, just was not sure if it was picking up noise or something, i have put a second set of coils on it as well as plugs, no help,,, guess i will continue to pull fuel and see if it cleans up.
grom_e30
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Re: high rpm miss

Post by grom_e30 »

if you were picking up noise it would cause sync loss, you do appear to get lean spikes in the problem rpm band this could indicate misfires, have you tried tightening the plug gap a bit to see if that helps.
1990 bmw 320i daily driver with m20b25 ms3 sequential fuel, 380cc injectors, d585 coil near plug, home made cam sync, launch control, fan control, vss, homebrew egt logging what's next????
chilly
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Re: high rpm miss

Post by chilly »

yes I have them gaped at .025, nkg non resistor and autolite resistor, no difference. I have been cautious on fuel and have taken 15% away so far but still maxing out a 63lbs injector, probably need to lean it further.
darkstar42
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Re: high rpm miss

Post by darkstar42 »

Are you using a pull up resistor on the hall sensor?
chilly
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Re: high rpm miss

Post by chilly »

yes i am
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