MSD Crank Trigger Sensor...

Old 05-25-2010, 07:01 PM
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BEAST477
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Default MSD Crank Trigger Sensor...

Is it possible for a crank trigger to seem to run ok but missfire at higher rpms? I thought they either worked or not. :? :?
Here's what I've got going on. Car seems to run ok till I leave the line and try to get over 6000 rpms. It starts missfiring. So I disconnected it and hooked back to the distributor and it will turn 7600 at the stripe. :shock:
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Old 05-25-2010, 07:18 PM
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johnracer
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Did you check the rotor phasing when you installed the crank trigger? I suppose that a sensor could break down and cause it to miss at high rpm.....but I've haven't seen it happen....yet. You may be picking up some EMI from plug wires or plugs with the long lead to the crank trigger. Make sure it's routed away from any high voltage sources.
Johnny
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Old 05-25-2010, 07:56 PM
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hammertime
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Default Re: MSD Crank Trigger Sensor...

Originally Posted by BEAST477
Is it possible for a crank trigger to seem to run ok but missfire at higher rpms? I thought they either worked or not. :? :?
Here's what I've got going on. Car seems to run ok till I leave the line and try to get over 6000 rpms. It starts missfiring. So I disconnected it and hooked back to the distributor and it will turn 7600 at the stripe. :shock:
what do you have the gap set at ? and rotor phased I assume ?
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Old 05-26-2010, 04:29 PM
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BEAST477
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Sorry guys, yes the rotor is phased. I'll have to double check the gap on the sensor.
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Old 05-26-2010, 04:47 PM
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hammertime
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Originally Posted by BEAST477
Sorry guys, yes the rotor is phased. I'll have to double check the gap on the sensor.
I've seen only a few things with the crank triggers, sometimes the pickup goes bad or sometimes a magnet flys off the wheel. But typically them are both missing all the way. The gap between the wheel and sensor is where I see higher rpm misses.
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Old 05-27-2010, 04:47 AM
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chevyfireball
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You want to make sure you have the replacement wiring for the trigger that MSD came up with a while back. It has shielded wiring and an earth wire.
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Old 05-27-2010, 06:31 AM
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hammertime
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Originally Posted by chevyfireball
You want to make sure you have the replacement wiring for the trigger that MSD came up with a while back. It has shielded wiring and an earth wire.
Not needed .. msd just wanted to make more money
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Old 05-27-2010, 03:30 PM
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TopspeedLowet
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Default RFI is possible but..........

If you happen to have the wires reversed from the trigger, meaning that the purple is not matched with the purple all the way to the IGN that WILL cause misfire. I had a pre-made wire from MSD that was backwards and I missed it. I had to adjust 10 deg difference from the correct wiring orientation and that should have made me check it then, but even with the correction in timing I had a high speed miss something awful.
As for the shielded cable, They are very useful if you are any where near your coil power leads or other current draws. The shield eliminates RFI that the two wires are very receptive to picking up.
Check the wires pal, otherwise the sensor is likely bad.
Bruce
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Old 05-28-2010, 05:36 PM
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BEAST477
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Thanks guys, I'll check all those things and let you know what I find. Won't be till next weekend since we're not racing this weekend.
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Old 06-05-2010, 05:41 PM
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I checked my gap and it is between .050-.055. My guess is that the sensor is failing.
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