Hello all,
I have a 2000 F150 with a 5.4 throwing codes of P0303, P0304. I figured it was the COPs going bad so I swapped them with #1 and 2 COPs to confirm. Cleared the codes and drove for a bit, only to see the same exact codes plus a P0171. Thought maybe it was the injectors since I’m getting a lean code. So I pulled the connector (one at a time) from #3 and #4 injector while it was running and got no response from the engine. Then just for hoots I unplugged the COPs to those cylinders to see if anything changes. Well guess what, the engine did respond when each COP was unplugged. The engine missed more but not as much as other known good cylinders would when unplugged.
Can a bad injector still spray enough fuel to affect the COP when unplugged, yet show no effect when the injector itself was unplugged?

Has anybody ever experienced this? Any thoughts, suggestions?

Thanks in advance!

 

I've got a similar condition... Staying tuned to see what solutions are offered up. Hope it's something easy to fix brother!