Ignition Coil problem

norcalsvt · Sep 30, 2007

Installed a new MSD Blaster 2 Coil. I have noticed ever since I installed it the car is hard to start. Occasionally it will start up with the first crank, but more often than not it just turns over but never catches. Eventually I can get it to start after 5 minutes or so. It happens in the morning or even after the engine is warm. I just tested the + side of the coil & it was over 4 volts, around 4.5 with the ignition on. I reinstalled the old one which was a Accel & it had around 7 volts with the ign on. I tried it & it fired right up. I do have a petronix so it does have 12 volts in the wire that goes to the coils positive side.
Not sure if the Blaster 2 coil is bad or not. Shouldn't I still have 12 volts with the wire attached to the positive side with the ign on since it doesn't go through a resistor?

Iamdiffrnt · Oct 1, 2007

Did you bypass the pink resistor wire in the dash?

BarnStang · Oct 1, 2007

THe Pertronix, by the instructions, is normall wired to switched 12v. If your wiring is stock, the coil is fed by a resister wire. Rubbery pink insulation as described in the previous post. THat pink wire runs from the ign switch to the coil. SOme people can run the Pertronix off the coil and have no problem. Others arn't so lucky. 4 v is pretty low at the coil. Even 7 is I guess average. Seems low to me. You should run a new wire from the ign sw to the red wire on the Pertronix ign and see if that resolve the hard start problem.

65fastbackresto · Oct 1, 2007

I just had a similair problem.

Installing a MSD 6AL in my car. Couldn`t get enough voltage to the power remote wire (the one that gets hot when you turn the key on), so I ran 10 gauge wire to the battery and hooked up a toggle switch under the dash, fused the wires going in and out of it, and ran a wire from toggle switch back to ignition.

This switch could possibly mess up somebodys game that was trying to steal the car too.

I had MSD tech line tell me to run the red wire directly to the battery first, to see if it fixed the problem.

norcalsvt · Oct 2, 2007

I did run it from a 12v switched source. The wire does have 12 volts when I test it without it hooked up to the coil. maybe the 12 volts only show when I crank the engine. Will have to try to get my wife to crank the engine while I test it.

BarnStang · Oct 2, 2007

Should have 10-12v at the coil with the key on. Pull the wire off the coil and see what you get. Maybe the coil really is pulling the voltage down. THe direct non-ballested switched 12v line goes directly to the red wire on the pertronix module. THe 12v source that powers the module. THe coil should/can still run off the ballest wire. Don't think I was clear before. When you crank the engine, a full non-ballested 12v comes from the right hand terminal on the solinoid to the + side of the coil. In run position the + side of the coil get power through the ballest wire. Now, there is 12v at that terminal on the solinoid, but it is the ballested power when the car is running coming back through the wire from the coil. It's only full 12v when the solinoid is clamped or on (start position)
Did that help or make it worse...

norcalsvt · Oct 2, 2007

BarnStang said:
Should have 10-12v at the coil with the key on. Pull the wire off the coil and see what you get. Maybe the coil really is pulling the voltage down. THe direct non-ballested switched 12v line goes directly to the red wire on the pertronix module. THe 12v source that powers the module. THe coil should/can still run off the ballest wire. Don't think I was clear before. When you crank the engine, a full non-ballested 12v comes from the right hand terminal on the solinoid to the + side of the coil. In run position the + side of the coil get power through the ballest wire. Now, there is 12v at that terminal on the solinoid, but it is the ballested power when the car is running coming back through the wire from the coil. It's only full 12v when the solinoid is clamped or on (start position)
Did that help or make it worse...

I did remove the wire from the coil & it is 12 volts when the ignition is on. When I put the wire on the +side of the coil & test it it drops to 7 volts with the key on. Not sure if that is what it's supposed to do or is the coil bad. the new coil I bought is even less at5 volts in the on position.

Iamdiffrnt · Oct 3, 2007

Ok, sounds like you still have the resistor wire in the circuit. When you are not pulling a current, as in not connected to the coil, you will not see a voltage drop on the wire. Think of it like this you have 12-14 volts, everything in the circuit is going to take its share of the voltage in that circuit when it is under load, for example with the coil connected. (I know not the best explanation, but I'm trying to keep it simple) So, if you are only showing 4-7 volts on the coil there is something else in the circuit using the other 5-10 volts. Which just happens to be about right for the resistor wire. Make any more sense?

Ignition Coil problem

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