DanFarmer

First time post.... I have a 2001 3.8L Mustang 215k miles. I had recently just put new Cylinder Heads in. Everything ran great for about a day then i started having cylinder misfires, fuel injectors go out and o2 sensors go out. After replacing all my spark plugs and putting the right measurement on them and replacing all my spark plug wires and putting 2 new fuel injectors in and a brand new o2 sensor. i can drive for about a couple days then i'm back to step one of cylinder 2 and 3 misfire o2 sensor still running too rich. Brand new coil pack as well all new gaskets from the heads up. Any idea what could be causing my misfire to keep coming back after putting brand new spark plugs and wires in as well as the 2 new fuel injectors? could my Cylinder heads be causing the problem?

Derf00

What was happening before that made you replace the cylinder heads?

DanFarmer

Was told from a mechanic my heads were warped a little bit which was causing me to have a oil leak. Had my heads cleaned and looked at and found out by the valves they were also cracked.

Derf00

who did the install work on the new heads? Most likely a pinched wire or wiring harness that is brittle and breaking apart.

DanFarmer

I installed the heads myself. I’m almost 100% positive nothing is pinched. I do plan on taking the heads off again due to the new gasket I have installed is causing me to leak coolant/oil and replace it with a better gasket.