Quote:
Originally Posted by Bmnorm2
I did a little research last night. It appears the air injection pump only runs when the engine is cold. By injecting air into the exhaust stream it burns the unburnt fuel which not only reduces unburnt fuel emissions but it also warms up the Catalytic converter faster and again reduces emissions. It's final benefit is to help the Catalytic converter last longer by preventing that unburnt fuel from reaching it. Just wanted to clear that up, i hate misinformation in forums. So, it seems the air injection pump doesn't run in any other condition once the engine/cat is warmed up. Again, not 100% on this.
OP, any updates on root cause?
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I took it to the original dealership I purchased it from today and had what they said was their best technician ride along with me. At first acceleration pulling out he said, "I hear it, and that is NOT normal."
He apologized for all the misinformation given to me and said his initial reaction is that does not have anything to do with the engine.
He agreed the sound is coming from behind the tachometer, but doesn't know what it is. He said he would do a build inspection, to make sure it isn't somethin obvious from quality control. If unsuccessful he will then start pulling things apart and investigating even more. If unsuccessful after that he is going to make a recording and get in touch with Toyota's service bulletin line. AND if that is unsuccessful they will be requesting a visit from a Toyota engineer.