KL-ZE swap, car chuggs between 1500rpms & 2800rpms

[bbunkerc397]

I get a bit of chugging once and a while but not all the time, only when engine hot between 1500 and 2800. Some times the engine light comes on, code "fuel trim malfuction" it clears. When doing the swap I replace two lower o2s bank1 sensor 2 & bank2 sensor 2 the onthers looked ok, new fuel filter, tested fuel pressure regulators, thier is no vacume leaks "smoke tested". I open for suggestions.

[Newfie_dan]

weak fuel pump or poor connections at the fuel pump perhaps, or look for corroded wiring at the 02 sensor plugs. I would check that wiring out and see if there is any corrosion in the plugs. also as a slim possibility there could be signal interference from the front 02 sensor if the wiring is to close to the distributor. I had that issue with a escort gt once, signal was not consistent causing some problems.

[mikeinaus]

could it be fuel filter?

[bbunkerc397]

Last night I checked the plugs conecting the 02s and wiring around distributor they look fine, today i will remove the back seat and check the fuel sender unit. Also it has a brand new fuel filter when I did the swap, should I put a higher volume fuel pump? Because bigger engine means more fuel? thanks.