Ignition Problem Under Load

[holanae]

Worked with Ron mid December to get a Firecore distributor and OE style ignition module installed. Took it to the tuner and put out 310/390 with timing at 25 and 38 at 2,400rpms. While on the dyno, we started having starting issues, and you could even see it on the plot curves. Prior to the dyno runs, I had never had a starting issue. It would start up on the first try cold or hot. Got it home and it wouldn't start. My tuner came over after work and we diagnosed it as the ICM went bad. I replaced the ICM and it started right up. Took it around the block and did a small burn out and it died. Got it started and back to the house. Turned off and wouldn't start. Burned up the ICM. Replaced it with another ICM and that one crapped out also. Right after a burn out. Spoke with my tuner and Ron, and they both stated to install a MSD. Installed a MSD Street Fire, and started right up. Did a small burn out in the drive way and the car started idling higher at 1,500 to 2,000 rpms. Turned off, gave it a few minutes, check everything. Started it back up and drove around again. Everything was fine until I did a full throttle kick down going down the road. Car started idling again at 1,500 rpms. Luckily the msd is a little more rugged so it didn't burn up this time, but something is definitely wrong. At this point, I've replaced the ignition module and coil. The only thing left to replace is the distributor. That's the only thing my tuner messed with during my test and tune session. Ron has been a huge help, but this one has me stumped. Could there be anything I am missing. I am leaning toward the distributor, but I can't see what it could be. It's just a magnetic pickup. I have inspected the inside of it and the wires. Nothing looks out of place.

Need help

 

[Don Frelier]

The stock module requires a ballast resistor. The MSD street fire does not.
When I installed the street fire I found I had to back off the timing, it started to ping. More initial could increase idle speed but I wouldn't expect more than 100 rpm, 200 at most.

As far as the higher idle speed, you need to check the throttle return and possibly mechanical advance.
1,500 is pretty high, what was it before?

 

[Johnpat]

Are the sure your throttle plates are not binding?
That would definitely cause your idle to be
higher.

 

[Johnpat]

Also check for vacuum leak,that will also cause
it to idle higher

 

[holanae]

I feel stupid, but I think I fixed the high idle. I went back and took a second look at the carb. The fuel log was barely touching the side of secondary baffle lever. Full throttle, it would open the secondary but the lever would get stuck on the fuel log. Let off the throttle and the primary would close down, but the secondary was allowing fuel it. ​

I can't explain why I was burning up ignition modules before. I had a ballast resistor installed. During troubleshooting I would run two different resistors. Install one and it would run at a higher rpm because it had a low resistance (0.5ohm), the other had a higher resistance (1.5ohm) and would run a lot lower idle. Because of the huge difference such a stupid little resistor made, I decided to go MSD. I think the ballast resistor was my problem all along but I guess I will never know. They say a 1ohm resistor is ideal, and I believe it. Can't explain why it ran good for three months prior to tuning, but I just drove about 10 miles without an issue.

Case closed

 

[Frank Mopar]

Running through the ballast resistor was putting 8 volts or so to the msd. Low voltage will kill any electrical device.

 

[Nacho-RT74]

The stock module requires a ballast resistor. The MSD street fire does not.

that's partially true... even is true doesn't need it, isn't necesary remove it either, since the coil signal with ballast in line is enough to remote turn on the module. RTR distribuutors require to remove/bypass the ballast because doesn't get an extra power source, but not the module. The Modules gets the power from the thicker wire, not from the coil/ballast wire

 

[Nacho-RT74]

Running through the ballast resistor was putting 8 volts or so to the msd. Low voltage will kill any electrical device.

once again, aftermarket modules are NOT sourced from coil/ballast wire, is just a remote on signal. The low voltage to remote on the module is fairly enough to turn them on and work! They are really sourced from the thicker red wire advised per insturctions to source from batt ( althought if you have a good alt, I will source it from alt side of ammeter, maybe a junction closer to ammeter to keep the correct loading readins on amm )

 

[PurpleBeeper]

As far as burning up ignition modules, I had that happen to me many years ago. I was burning up maybe one ignition box per week & couldn't figure out what was happening. I finally noticed that I had pinched the blue ignition wire under the very corner of my intake manifold during a carb/intake swap ("run" hot wire coming from bulkhead disconnect that powers ignition module). So, you might check that blue wire for bare spots or a short somewhere? Just a thought.