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SiennaGeneral discussion forum for the Toyota Sienna.
This is a discussion thread titled "Vacuum Hose Reroute Increased Fuel Economy", within the Sienna forum, part of the Cars & Vans Forums category.
I rerouted the vacuum line from the air box to the vacuum switch valve that opens and closes the second intake flap. The new line goes from the vaccum source (air box fitting) directly to seconf intake flap fitting. It nows has vacuum all the time. My last tank say 1.1 mpg improvement. Same drive same weather same everything else.
Well I just did this mod on my 2004 Sienna and first impression is very positive! It feels like there is less lag down low when first opening the throttle and then it seems like it accelerates a little easier and smoother. I will leave it like that and report back after a month or two and let everyone know if our mileage is affected.
Well, over the long term, I can't say it has really done much for our fuel mileage. The average is the same to slightly better but not enough to crow about. It certainly doesn't bother the motor, so I have no reason to go back (plus it was free).