Dealer repeatedly recommending "Fuel injection Air mass Service" for my 2010 Prius

WHAT? What ever is pushed out through the late closing intake valve is pulled into another cylinder that is in its intake stroke.

NO air or fuel is pushed back through the air filter. There is always negative pressure on the engine side of the MAF sensor. It wouldn't and couldn't work right if their was air flowing in both directions.

Must be CYA part just in case during shut down gasoline fumes migrated back up through the intake system. I checked, and all aftermarket engine air filters offered, do not come with an activated Charcoal layer on them only the Toyota OEM filters.

 

No Toyota PRius OEM filter has a charcoal layer, as far as I know. I believe the charcoal impregnated filter being mentioned is a little auxiliary filter, a permanent part of the filter housing?

 

The definition of regurgitate, and it moves back through the intake manifold.

I didn't say it would be pushed back. Gasoline is volatile and any in the intake manifold with the engine off would reach the MAF sensor -would it not?

The OEM charcoal element is inside the air box just above the air filter. It sits between the air filter and the intake manifold.

My point being - how many times during a drive does the Prius typically turn off it's engine? Is that not way different from any Volvo?

Old gasoline can form varnish inside a gas tank because it can oxidize. Can't the gasoline fumes do the same thing inside the intake?

 

I'm sure there is the possibility that it could happen, but I don't the see excess gasses making it through the air filter and back up the intake hose to the MAP sensor. And anything left will be pulled back in the next time the car is started.

I do agree with cleaning the intake, but I don't think that the Prius needs any extra special treatment because of its design.

 

The gasoline vapors don't need to make it past the air filter or charcoal filter to reach the MAP.

 

Now that I think about it, it's the throttle plate that prevents the gas from reaching the MAP. That's assuming the throttle's completely closed when the engine's turned off

I guess the charcoal filter's there in case the throttle gets stuck open. So I digress.

 

Digress away.....it's ok. Isn't that what we're all doing?

 

Pretty sure many here would like to see the redacted letter(s), and know which dealership this was.

No one should endure high pressure sales tactics, especially the environment

 

Next week is Power Mode test in my Unscientific economy testing thread, but the week after is Fuel treatment week. You may want to check it out. I may go all out and clean the intake after that one!

 

Maybe the cabin filter

 

Mass Air Flow (MAF) sensor is on top of the air filter housing, just unscrew 2 phillips screws and spray it with Contact or Electric Cleaner. Do not use brake cleaner or anything stronger, especially non-chlorinated brake cleaner that contain Acetone (B12 Chemtool). It will eat rubber, plastic, etc through microcrack that you cannot see. The MAP sensor is at the bottom of the throttle body, that one never need cleaning. Even it is merged in pool of oil+gasoline mixtures for decades.
Replacing air filter, cabin filter, clean battery fan filter on the rear, throttle body and MAF is a good practice for every year or 2 years.