Nissan Sentra 2008 Base 2.0L High Negative Fuel Trim in acceleration.

Hello
I own Nissan Sentra 2008 base model with 2.0litres CVT transmission.
Since i purchase the car from the last owner, being having high negative fuel trim when coasting or acceleration, but lesser at idle when monitored with a scan tool.
Being trying to figure out whats wrong with my car because its hurting my purse with its bad fuel economy.

Have noticed long engine crank at cold start, rough idling sometimes and erratic acceleration.
The codes present related are P0300, P0304 but my coils, plugs, injectors, maf sensors are all in good shape after check ups.

My suspect: Faulty or bad fuel pressure regulator.

Help me guys, dont hesitate if you need scan tool outputs to help your judgment.

Thanks

Hi Mario,

What are the trim numbers at idle?

Let us know also O2 sensor voltages. That way we can asume if O2 sensors are telling pcm the truth.

If so, could be fuel pressure reg, leaking injectors (which match with a hard start).

Did you already check fuel pressure? Could be some other issues, but let start with O2 and fuel trim readings.

Pull the vacuum hose off of the regulator and check for fuel leakage.

Sure
To the best of my knowledge 02s are cycling good, but will share a quick video link on its cycling tomorrow for your watch.
Have attached trim numbers at idle.

Ok
Will do this and revert.

You have issues also at idle.

I would also play around at any source of fuel (pcv, evap, unpluging injectors one at a time, leaking pressure reg) and meanwhile keeping a eye on fuel trims.

Once you cut the source of uncontrolled fuel, STFT should compensate LTFT number.

Check below address for the 02 video.


Also my fuel system is returnless so no vacuum line

Sure, as I said have already worked on those items mentioned with exception of only two culprit. The fuel pressure regulator and pcv, but can pcv cause this and this high figures of negative trims?

Yes, it can. I mean, oil contaminated with fuel.

If so, oil was contaminated for something else (which is the root cause).