Misfire problem, Bank one Fuel trim

[Lurcher]

Looks like a lifetime smokers lungs....

 

[MacBB55]

to me, it looks like you sucked up some loose gravel from somewhere, lol

 

[Second325]

Wanted to say thanks to MOSFETS Forever for this post. I ran into the same issue. Secondary cat was clogged with parts of the primary. The back pressure caused the fuel trims on bank 1 to go negative, the ECU then leaned it out resulting in misfires.