During our last firing of the “parts cannon” I replaced all 8 injectors. We had a loss of fuel pressure when it was just ‘sitting’ after shutting the engine off. (Some injectors where slightly weepy). The ones I installed came off a newer model Jeep with the same 4.7 (same part number stamped on the injectors) I hooked up the injectors into the rail before installing the rail into the intake and ran a quick and dirty check. No weeping, Decent spray patterns on all. Resistance on the injectors ran from 11.8 to 12.3. I knew we had that for an issue, so that’s been removed from the naughty list.
The light coating of blech might be blowby. This ol’ gal has almost 200,000 on the engine. Runs like a scalded dog just about every other time! Just that entire bank of misfires. The last owner was also fighting with the same issue. Pity he spent all his money on cheap eBay parts. (Found 2 physically broken O2 sensors…1 dead sensor. And the last one he fiddled with was another eBay knock off. Everything was replaced with the Denso brand.
Just find it odd that when all the misfires happen, It’s all 4 cylinders on Bank 1. It’s not tripping any codes for open or shorted wiring for the injectors or coils. Thought maybe a mouse decided to have lunch. God knows we pulled enough mouse nests out of the blower box.