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Voltage at Positive Terminal of MSD Blaster SS Coil

Started by _Ryno364_ , Mar 15 2017 09:00 PM

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6 replies to this topic

#1 _Ryno364_

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Posted 15 March 2017 - 09:00 PM

Hey guys, just wondering what the minimum voltage requirement is for a MSD Blaster SS coil to generate a spark. Anyone have any readings handy at the positive of coil when ignition is on and while engine is cranking?

Is 12 volts + at the coil while cranking required?! Am also running a MSD pro-billet ready to run dizzy.

Thanks Ryan

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#2 S pack

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Posted 15 March 2017 - 11:34 PM

If your car is running a 12v electrical system then you should have at least 12v supplied to the + terminal of the coil (regardless of what coil you use) when starting (cranking) the engine.

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#3 _Ryno364_

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Posted 16 March 2017 - 01:15 PM

Am measuring 12.6v at battery and starter motor. 12.5v at the coil with ignition on and comes down to 10.8v when cranking (relay used per MSD recommendations) therefore I need to find that extra 1.2v + for the MSD coil to produce a spark.

Have a new Optima red top battery (load tested and passed no probs at all), 38mm square cable from battery direct to starter (approx. 300mm length and rated for 255 amp current flow), 2 of 38mm square earth cables running from block to negative and chassis to negative (Ohms / resistance checked all good). Starter motor is a new high torque 2.4hp unit.

All other ignition and battery circuit have been tested with a voltmeter and earths are good - no issues.

This is really starting to do my head in now, what could be the cause of such a big volt drop at cranking? Could it be the high torque starter hmmmmm

Just curious what are other people getting at there MSD coils while engine is cranking?

Thanks

Edited by Ryno364, 16 March 2017 - 01:20 PM.

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#4 _Ryno364_

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Posted 16 March 2017 - 01:32 PM

Am measuring 12.6v at battery and starter motor. 12.5v at the coil with ignition on and comes down to 10.8v when cranking (relay used per MSD recommendations) therefore I need to find that extra 1.2v + for the MSD coil to produce a spark.

Have a new Optima red top battery (load tested and passed no probs at all), 38mm square cable from battery direct to starter (approx. 300mm length and rated for 255 amp current flow), 2 of 38mm square earth cables running from block to negative and chassis to negative (Ohms / resistance checked all good). Starter motor is a new high torque 2.4hp unit.

All other ignition and battery circuit have been tested with a voltmeter and earths are good - no issues.

This is really starting to do my head in now, what could be the cause of such a big volt drop at cranking? Could it be the high torque starter hmmmmm

Just curious what are other people getting at there MSD coils while engine is cranking?

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#5 _76lxJAS_

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Posted 17 March 2017 - 03:47 PM

How is the relay wired? And or try replace it. Could be a dodgy relay?

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#6 _Ryno364_

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Posted 18 March 2017 - 12:09 PM

Relay is all good Jason, checked it out with the voltmeter. Had an auto sparky around and we are 99% sure it is the internal module in the pro-billet dizzy. Will get another one and see what happens from there.

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#7 hanra

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Posted 19 March 2017 - 10:28 AM

So I take it you have disconnected the 12v output from the relay (which goes to the coil) and measures the voltage directly on the relay when cranking? And while you were at it, I guess you measured the 12v supply to the relay whilst cranking?

Edited by hanra, 19 March 2017 - 10:29 AM.