AboutTed Ritter Expertise I have more than 26 years experience as toyota technician, I will be able to answer most questions related to the toyota product line up to the present year models, I specialize in difficult to diagnose problems but when posting a question please keep in mind that some situations require the used of special test equipment and diagnostic procedures especially as the newer models become more technologically advanced, so without actually having the car on hand I may only be able to try to steer you in the right direction and in some cases may have to refer you to the toyota dealer but at least you will know what you may be dealing with. Please don't hesitate to ask any questions, I will have an answer for you in most cases. When posting a question keep in mind that I reside in the US, although I get questions from all over the world I may not have an answer for models that are not sold in the US, I will do a reasonable search to try to match your model to the US model,please refrain from asking about diesel powered vehicles, I have no information for them. In most cases I will not answer questions about major modifications of OEM components, engine swapping or aftermarket products,please post a question not a statement, please provide enough basic information such as year, model, what engine and if anything has already been done to fix the problem, the more information I get the more I can help without having to ask you more questions.
Experience Toyota technician since 1979,expert in electrical systems,OBD systems,engine repair, driveability problems,EFI systems,ASE certified,Toyota master technician. Certified Hybrid Vehicle technician.
Education/Credentials Toyota master technician, ASE certified in eight catagories, Hybrid vehicle certified.
Question QUESTION: My friend's 2000 Corolla hesitates bad from a cold start and to a lesser extent after warmed up while accelerating or revving the engine in park with or without the AC engaged. It's pulling 2 codes, p0300 & p0171 The air filter & spark plugs are new. It also shows 1-2 misfire on all four cylinders when revving the engine. Any ideas on what the problem is? Thanks
ANSWER: The p0300 is a random cylinder misfire detected, the p0171 is a lean fuel trim condition which is more than likely caused by the misfire so the misfire should be addressed first. Are there misfire codes p0301,302,303 and 304 also present? If not all then which ones?
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QUESTION: Thanks Ted, but today I took out the MAF sensor and cleaned the 2 little wires way down inside and now the car runs better than it has in a long time. Thanks for your help.
P.S there were only p0300 & p0171 codes
Answer You did the right thing, the p0171 code by itself is normally due to a dirty MAF sensor and if it was the only code I would have recommended doing what you did but the fact that it had misfire codes was my primary concern, let me know if i can help in the future.
