I was wondering about the charcoal filter on the underside of the lid for the engine air filter. Someone said it never needs replacing, but that doesn't make sense to me. If it is for absorbing fumes, it will eventually, I would think rather quickly become deactivated and that would be a regular part of the maintenance.
I believe the carbon filter is to capture any gasoline vapors which are flowing in the wrong direction after the engine is shutoff (wafting up from the intake manifold). Once the engine is started the forward flow of fresh air will remove the gasoline caught in the charcoal, so that it is ready to capture another batch the next time the engine is shutoff.
That is correct. Both it and the ones used for the fuel tank vapour self clean. You burn the vapour they collect. They are really a "temporary storage system", and a filter. BTW, the one for the fuel tank is, I believe, IN the fuel tank.
This would only be a problem if you are in the habbit of squeezing in the very last drop of gas at fillups. This would eventually result in an expensive charcoal cannister failure.
That all sounds too good to be true. The charcoal 's ability would have to eventually become exhausted over time. I would like to see tome real data regarding this.
Hard data is available. Look in your service hand book and see how often you need to replace the "carbon filter". Toyota would have to specify a periodic replacement if there was a limit to the life of the "carbon filter" which was less than the life of the vehicle or at least less than the life of the statutory warranty on emission systems. Don't worry about it, Toyota aren't.
