[Note: This is a placeholder for a more lengthly post--a work in progress. More to follow.]
Common problem with '87--'95 TBI "Small Cap" HEI distributors. The Ignition Control Module gets blamed for poor performance when the real issue might be in the pickup coil assembly.
I'm not saying that ignition modules can't fail--they do, and generally because they were murdered by the ignition coil. However, a FAILED CERAMIC MAGNET on the pickup coil assembly can result in a weak or erratic signal from the pickup coil, which can fail to trigger the module, or "drives the module crazy".
Point being, LOOK at the magnet and the pickup coil itself, if you suspect ignition module problems.
Photo 1. Well-used, zillion-mile, thirty-year-old TBI "Small-Cap" HEI distributor. V-8, V-6 similar.
Photo 2 and 3. Pickup coil assembly surrounding the magnet on the mainshaft. Broken magnet directly under the "©" Copyright symbol. The crack extends all the way across the magnet. It probably started due to the pressure from setting the rivet. COMMON AS DIRT.
Photo 4. "New" replacement distributor mainshaft. No pickup coil or metal shielding installed.
If the magnet is broken--or weak (!) the pickup coil doesn't generate a proper AC waveform for the module to trigger from.
Common problem with '87--'95 TBI "Small Cap" HEI distributors. The Ignition Control Module gets blamed for poor performance when the real issue might be in the pickup coil assembly.
I'm not saying that ignition modules can't fail--they do, and generally because they were murdered by the ignition coil. However, a FAILED CERAMIC MAGNET on the pickup coil assembly can result in a weak or erratic signal from the pickup coil, which can fail to trigger the module, or "drives the module crazy".
Point being, LOOK at the magnet and the pickup coil itself, if you suspect ignition module problems.
Photo 1. Well-used, zillion-mile, thirty-year-old TBI "Small-Cap" HEI distributor. V-8, V-6 similar.
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Photo 2 and 3. Pickup coil assembly surrounding the magnet on the mainshaft. Broken magnet directly under the "©" Copyright symbol. The crack extends all the way across the magnet. It probably started due to the pressure from setting the rivet. COMMON AS DIRT.
You must be registered for see images attach
You must be registered for see images attach
Photo 4. "New" replacement distributor mainshaft. No pickup coil or metal shielding installed.
You must be registered for see images attach
If the magnet is broken--or weak (!) the pickup coil doesn't generate a proper AC waveform for the module to trigger from.
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