Re: Troubleshooting persistent misfire
Reply #20 –
Make sure you don't have the LH and RH oxygen sensor connectors swapped. I did this inadvertently when installing the 5.0L engine in my car and I fought a rough idle and random cylinder lean condition for a few months before I figured it out. The car would run great in open loop, but when it warmed up and went into closed loop it would run like , because it was leaning out the wrong side of cylinder banks. It's an easy mistake because LH and RH connectors are keyed the same, yay Ford