Hello, I have a 2002 Subaru Outback 2.5L. all wheel drive it has a horrible flat spot in acceleration that is much worse when cold than after warmed up I replace the plugs,wires,air filter & gas filter then took it to a mechanic he scanned the computer and found no codes present. He thinks it feels like a throttle position sensor.Have you ever heard of this problem do you have a better answer the mechanic says the throttle position sensor is expensive and can't be returned so any help would be appreciated.
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By far the most common cause for your symptoms is an air fuel sensor that is indicating a false rich condition.
Here is a thread that will help:
The throttle position sensor can fail and the pedal position sensor can also fail, however, the most common problem is the air fuel sensor and it can be proven out by the readings described in the thread I just posted.
Thanks for the question, please use the accept feature to complete the process and then come back and post your results as well as any other questions related to this concern.
Over 25 years of automotive experience
Is the front Air Fuel Ratio sensor your speaking of the front oxygen sensor if not where is it located?Thanks
Yes, the front sensor that looks like an oxygen sensor is actually an air fuel sensor. The rear sensor is an oxygen sensor. Thel difference is that an air fuel sensor uses a very narrow bandwith at a higher voltage and makes the data interpretation more difficult than that of an oxygen sensor, however, the use of fuel trim data and the rear oxygen sensor helps immensely in identifying its failure