Quote:

Thanks for all the ideas guys, I appreciate the suggestions so far.

I managed to get out in the garage again today and with the new coil in, I got it to run for about 45 minutes straight while I tested various voltages, etc.

It seems the motor is fine (doesn't drop idle speed) if the voltage on the high side of the coil stays above ~4V. I noticed that with the fans on @ in-gear idle, the voltage on the coil starts dropping to 3.8-3.9V which makes the engine idle lower (weaker) which spins the alternator less which lowers the voltage and so on until it dies.

I went ahead and fiddled with the engine harness bulkhead connector and the ignition switch harness to dash harness connection and managed to get an extra .2V or so on the ignition side of the ballast which gave a lil more "oomph" to the coil. With that little bit extra the engine stayed running MUCH longer and didn't die on me. I measured all the volatges and I am seeing a net loss of only .8V from + battery terminal to ballast now.

I am guessing the issue may be the Blaster II coil I have "wants" more voltage (and current) than the stock coil would. My ballast resistor is sitting at near 2 ohms across it which is dropping the voltage from 14+ to 4 volts on coil or so which is marginal from what I see. I ordered an Accel ballast which is supposed to .65 ohms and a Mopar ballast which is supposed to be 1.4 ohms. I am going to try both of these to see if I can't get some more voltage and current on that coil. BTW, the ballast they recommend for this coil (and, yes it SHOULD have one) is .85 ohms. I am hoping by getting rid of some of the voltage drop on the ballast I can better "feed" this coil even if the alternator drops to 700 RPM in gear and falls behind.

I also found that the brown pin on the brand new M&H dash harness I have was pushed back out of the Molex connector probably causing a weak connector on the start circuit. I fixed this and packed that connector with dielectric grease as well. This helped with some of the voltage drop I was seeing.

Hopefully I will get the new ballasts in by this weekend and I can fill everyone in on if this helps my issue.

Does anybody else here run a Blaster II coil with the MP Elec Ign? If so, can you tell me what your MSD coil "likes" as far as voltage goes and/or what ballast you run?

Quote:

During this test you'll still have the coil wire off the distributor and 1/4" from a ground point. And yes, this tricks the ECU into firing the coil.

In my case, I had weak/no spark while cranking (gap too large), but had an avalanche of HUGE sparks when I tapped the plug to ground.

If it dies and you have good spark with this test, then it shows the ECU side is ok, and narrows the problem to the pickup side.

You might also jump battery voltage around the bulkhead/ignition switch to make sure you have good voltage to the ECU/BR.




I did this test with engine hot and cold. Both times getting good spark! I used a spark plug tester to connect the coil wire to ground and a remote starter to jump the pickup connector to ground. Worked like a charm and I could see the strength of the spark! With the engine not running, I was getting 20-25 kV of juice! So I guess this means coil and ECU are good?

Thanks again to all you guys for you help and suggestions!!



According to the Mopar Performance catalog..
When using a Blaster coil, the correct ballast resistor value is 0.25 Ohms which is Mopar #P2444641. A higher value ballast resistor will greatly decrease the primary voltage to the coil and its respective HV output...


Just my $0.02..