Car Bucking During Acceleration

I have a 2002 Nissan Sentra GXE manual. Recently, I replaced the right, before O2 sensor and the rear and front catalytic converters becuase my car was regularly losing power. Now, my car seems to be doing better, except that often in the lower gears the car is almost bucking when I am accelerating. Plus the computer is reading back that the O2 sensor I replaced is bad, even though the mechanic says everything else indicates that it is fine. Does anyone have any ideas about why my car’s acceleration is acting so strange or where to look next for the issue?

What led you to replace the catalytic converters? Those are expensive parts to be replacing without good cause.

How about the basics: spark plugs, ignition wires, air filter, and especially, the fuel filter.

Is the “Check Engine” light on currently? If so, what error codes are present?

Check the plugs. Ask if your vehicle also has a 2nd O2 sensor that is located near the exhaust. There are some vehicles that have one towards the top which is common to go first. There is another on some vehicles that is usually located towards the rear of your muffler or in that general area. My car did the same thing after i replaced my O2 sensor. If replaced the other one and it was fine. It a little more money, but nowhere near as much as a catalytic converter

May 28, 2008

My 87 Subaru experienced fuel tank liner plating failure, and little white particles constantly clogged the fuel filter during high fuel demand (accelerating, going uphill, high speed). Eventually I had the fuel tank steam removed and steam cleaned of a tenacious layer of these white particles and the car runs fine. Have your mechanic replace the fuel filter, save it for you, and check its contents – if the filter is white and the particles are white they may be very difficult to see.

My 87 went through the entire period of Anchorage’s oxy-fuels from 1992 to 2004 and the change in fuel chemistry is suspected as a cause. Diesel user are also experiencing problems, see

Paul Todd
Anchorage, Alaska

Post the codes you are getting. Usual 02 sensor codes read something like ‘sensor 1 always low or always high’. There are engine conditions that can cause this so sometimes you have to find the reason the O2 sensor is reading what it is rather that assuming that the sensor is bad. If you a getting a lean condition DTC, look at the fuel pressure, fuel filter, fuel pump, vacuum leak etc. If you are getting a rich condition look at leaking injector, leaking fuel pressure regulator, etc.

Hope this helps.