HEI Shielding??????? (Page 1/1) jaydaug2008 AUG 10, 01:41 AM Can someone explain what the heck this means? I would love to diagnose it but there is no info. All I see around is this.. Check for proper ignition module shielding. If the ignition module is not properly shielded, the ECM might mistake the electro-magnetic interference for reference pulses, causing too much fuel to be delivered to the system. fierofool AUG 10, 07:52 AM I'm having the same issue on a 7730 conversion. Though not a distributor, it still has an ICM. If you have faulty spark plug wires or poor ground on the ICM, or if maybe the spark plug wires are routed really close to the ICM harness wires, the leaked electro magnetic pulses can be intercepted by the wiring to and from the ICM and the ECM thinks it's a valid signal. I assume you are getting Code 42? The first thing I would check regarding fuel delivery would be to unplug the cold start injector switch at the passenger front corner of the lower intake manifold. It's the multi-wire harness. Squeeze the spring clip and pop it off. The single wire harness is the fan switch. If that doesn't fix the situation, then replace the coolant temperature sensor located horizontally in the passenger end of the lower intake manifold, just above the water pump, as I suggested in one of your other threads. FYI, the correct sensor has an oval head and doesn't require a new harness to be spliced in. Avoid brands like BWD. NAPA brands like Echlin or discount house brands like Standard or Delphi seem to be of pretty good quality.