Originally Posted by Joekaistoe

I just installed a TFI coil and HEI igniter based DLIDFIS on my car.

It was hard to start, and on high idle (I don't have a choke) it was misfiring a bit more than usual, so I was a little disappointed. Taking it for a test drive, it seemed to accelerate and drive almost the same, but lower rpms were smoother. It stalled a few times at idle, and was idling really low.

When I got it back home, I checked the timing and it was dead on. Unplugged the trailing, and it immediately stalled. Checked the ignition timing on the back rotor (should be the same) and there's the problem. The back plug is only firing half the time.

Switched the plug wires, no change. It's either a bad coil or module, and I used a brand new Delphi module on that side, so dollars to donuts it's the coil. Going to pick up a replacement at the junkyard tomorrow.

​​​​I'm almost jumping around in excitement. If it runs nearly as good as before with a bad coil, I can't wait to see how well it'll run when it works properly.

Originally Posted by GSLSEforme

Need to go back and fault trace your ignition setup. The fact that car stalls when disconnecting trailing ignition proves you do not have functional leading ignition. Also responsible for all your above complaints. Car will run fine on leading ignition only,trailing ignition is for cleaning up combustion leftovers for emissions. As you have seen,will run on trailing but not well. Suggest leaving trailing disconnected while diagnosing leading ignition issues. Check your wiring from pick ups to module and module to coil- before you start replacing parts. You can substitute the trailing module for the leading-as you know it works to eliminate possibility of bad leading module. Post back what you find.

Originally Posted by Joekaistoe

Dug through the ignition problem a bit more Saturday, checking the firing with the timing light. Used a couple different coils, switched plug wires, checked the coil harness, wired ignition modules to opposite coils. Common denominator: the brand new ignition module. The module doesn't even heat up significantly.

Either it is a bad module, or there is a very strange interference problem because I used that module's bracket as a ground collection point before running a main ground to the strut tower ground.

Originally Posted by t_g_farrell

How did you mount the HEI? Did you make sure to add a ground to the one screw hole through the HEI with the metal collar on it? You have to ground it at that point or it will have issues.

Originally Posted by Joekaistoe

Yep, have a ring connector attached to the collared hole, wired to ground. I think I'm going to have to switch the module out for the junkyard part I originally planned to use. I only didn't use it because it's a goofy Canadian version with small tabs. (Think small distributor 7 pin module with 3 pins missing.)

Originally Posted by GSLSEforme

In 1st post you stated disconnecting trailing ignition caused car to shut off =no leading ignition. You further stated you found the problem,rear plug firing 1/2 the time-which plug,leading or trailing? Need to systematically eliminate causes of problem,don't want to be chasing your tail...
Some suggestions: put everything back to the way you initially had it,pull all plugs,insert plugs back into coil wires and lay all plugs on the keg to ground them. Have someone crank car for you so you can watch the plugs firing and determine which aren't(likely leading) and focus on that part of the system. Another route if you have no assistant... remove dist. cap,mark position of rotor on distributor body & position of distributor body on front cover so you can reinstall dist.in same position when done diagnosis. Remove dist,pop cap back on,turn key to run position and spin the gear on bottom of dist. and look at the plugs to see which are firing. This is actually my preferred method for extended testing of ignition system(i use a spare dist.). You don't need a 2nd person,you're not loading up the engine with fuel from repeated cranking and you don't run the battery down from repeated cranking with the starter. Note; be sure not to crank the engine over with dist. out-this way you can slip dist back in and line up your marks and be good to go. Stuff a rag in dist. hole in front cover so nothing gets dropped in unnoticed.

Originally Posted by GSLSEforme

So by now you've determined what you have and don't have for spark. In reading your post you've done a bit of switching around of components to no effect. Assuming your wiring is correct,new components are good. Whichever system is firing consistently, switch the W&G wires from that module and hook them to the other module. Spin dist.shaft and see if the other ignition system is now working. If it is,fault trace the wiring from the pick up coil that's not firing ignition coil/plugs. Pay particular attention to your connections to the pick up coil, often in these conversions,problems can be traced back to here. The pick up is a signal generator and correct polarity must be observed when hooking trigger harness to module. W gets green wire,G gets red wire,best to use a lighter (18)gauge wire and twist the wires so signal is not corrupted between dist. and module. If the problem is not in the trigger circuit, switch pick up wiring back to module it was originally working with,verify it still is,then switch one component at a time into the functioning system. Module/coil,plug wire(s) til functioning system fails. Verify system works again by swapping known good part back in,determines for sure faulty part if there is one.