QuestionQUESTION: Hi Russell,
My vehicle has about 65,000 miles on it and is well maintained. I am having a problem with intermittent light bucking/jerking at a STEADY speed only. This is most prevalent when the engine has not reached normal operating temperature yet such as driving first thing in the morning but can happen anytime. Acceleration is fine and the vehicle drives and runs good all other times. The check engine light is not on and there are no codes in the computer. Thanks for your time.
ANSWER: I see this concern very often, so it's somewhat of a no-brainier. You have a problem with the upstream O2 sensor. What happens, especially on higher mileage vehicles, is that the sensor gets somewhat lazy and doesn't send the correct info to the engine controller that it need to adjust the fuel injectors. If it gets bad enough it will set a DTC and turn on the "Check Engine" light. However, in your case the condition does not last long enough for a DTC to set. I'd replace both O2 sensors. The only reason I'd do both is that is the you could end up getting a Catalyst Efficiency DTC, which will turn on the CEL quickly, because the upstream O2 sensor is new and wants the downstream sensor to react as fast as it does.
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QUESTION: Thank you very much. Would you recommend Mopar O2 sensors or would it be okay to use Bosch? The reason I ask is because I have read on a couple of online forums that the Bosch sensors do not work well on some Chrysler vehicles and will set a DTC. Your thoughts?
I forgot to mention in my original question that the vehicle is only getting about 17-18 mpg on a tank of gas with a 50/50 mixture of city and highway driving. Could the O2 sensors cause the poor mpg?
AnswerI would recommend you use the MOPAR sensors. Although Bosch does manufacture a majority of the O2 sensors in use, the sensors available through the aftermarket are calibrated generically and not a direct replacement sensor for any vehicle. And yes, a faulty O2 sensor will affect your gas mileage since it can't send the correct readings to the Engine Controller. which are needed to adjust the fuel mixture
