Hi guys, hope somebody can help. I have '97 Expy with 5.4L. I scanned P0351 and P0353 codes. Bought new coils and replaced cylinder #1 and #3. But still missfires. When I pull out power connector on #1 and #3 (with new coils), makes no difference in engine sound. When I pull out other coils power connectors, makes difference in engine sound.

Anybody can help? I am stonewalled.

 

Must be further upstream in the wiring then.

Have you tested the coils operation with a Multi-Meter?

 

Thanks for reply. Yes I did test them. Old coils showed 0.5-0.6 primary, and nothing for secondary circuit. So I assumed they are bad right away. New coils showed 1-1.1 for primary and 5400 for secondary. Also I used test light on power connector and it worked fine.