Ron70

I have a 97 pathfinder, at 3200 rpm it looses power. it has a P0420 code I was told by the previous owner that the exaust was replaced a year ago. Can the 02 sensor or evap system cause this issue?

SPEEDO

sounds like a bad cat....

rogoman

A P0420 code indicates that the right bank CAT is not working properly. It could be a bad CAT, exhaust pipe leak, leaking fuel injector or an intake system vacuum leak.

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Ron70

from what I am told the cats were replaced a year ago. I has awesome acceleration unitl 3150 then feels like it levels out and theres nothing more. I was told today that the Throttle position sensor could be the culprit?? Or fuel pump... lost as hell.

smj999smj

A lot of things "could be" the culprit, but testing is the only way to isolate what the problem actually is. Test fuel pressure with a fuel pressure gauge. Exhaust restriction can be tested with an exhaust backpressure tester. TPS can be tested with a multimeter and scantool. An O2 sensor will often, but not always, set a code, but can also be tested with a scantool. Diagnosis is often a process of testing and elimination. Of course, make sure your filters and secondary ignition system are in good condition.

Ron70

changed the fuel filter (it was clogged) and tuned up it does better, but still "levels out " at 3250. can the IAC cause this or should I go ahead and change the fuel pump????

smj999smj

IAC is for idle control, so it will have no affect on an engine at 3250 RPM. I wouldn't recommend spending money on a fuel pump unless you confirmed that the fuel pressure was not within specfications as tested with a fuel pressure gauge.

Ron70

Thank you for the advice ...it is fixed it did not need the fuel pump...it WAs the filter as you suggested. AND the plugs cap and rotor.. I checked the gap in every plug they averaged at .55lol