Manual car temporarily loses power.

[shiwei]

I have a 6-speed manual Nissan Sentra SPEC-V 2.5L. But I have a quite weird problem.

When I am driving at around 30mph with 3rd or 4th gear in city area, with right foot on pedal without any movement, it car temporarily loses its power, just like the pedal is released a little bit. Then 2 seconds later, it restores the power and goes back to normal.

I tried to drive the car to 40 mph, then let it go in Neutral position, no problem, so the problem could not be the tires, etc.
I tried to drive the car to 40 mph, then let it go in 3rd or 4th position, but the left foot firmly pressed the transmission so engine was not geared to transmission, no problem, so the problem could not be the transmission gears.

It seems the problem could be the engine. My guess could be the fuel pressure regulator, fuel pump/filter, and I plan to read live data with an OBD scanner. Any suggestions on how to find the reason?

Thank you.

Topic

[Andrew Phillips]

Could be an air issue causing it to go lean at that point. Inspect for leaking air intake or a dirty/failing MAF sensor. Try to eliminate the obvious causes first. Scan tool data may help.

[Mike]

Look at the live data for an obvious change in your short-term fuel trim (STFT) when the problem is happening. The same would be true for the MAF sensor, MAP sensor, and throttle position.

[Author]

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