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04 Sienna 3.3L -50k mi -how best to inc. mpg


cjstew4
09-16-2009, 12:59 PM
Besides changing driving habits, what are the next best ways to increase mpg. With 50k mi, never had plugs or any other item like that changed. Just the normal oil changes and other scheduled maintenance. Someone told me to run super-unleaded instead of regular. The owner's manual seems to point to using 91 octane, but not absolutely required. Would injector cleaner work instead? thanks.

jdmccright
09-22-2009, 09:37 AM
You don't mention what mpgs you're getting now. If it's below the EPA estimate, and regular maintenance has been done, then it's likely due to driving conditions...stop & go traffic, high outside temps with A/C on, etc. If not, check all the regular tune-up items first and get those in top condition...plugs (clean & regap or change), injectors (clean), plug wires (check/change), fluids (check/change), tires (pressure check & look for abnormal wear), alignment (signaled by abnormal tire wear), brakes, suspension (abnormal bounce or rattling).

There are minor mechanical changes you can make to eke a few tenths out, such as high flow air filter or CAI, higher flow exhaust (on a Sienna?). I've seen some mech shows on TV that have shown positive results (albeit small) from the E3 spark plugs...not an endorsement as most of those "super" plugs are only super expensive. But from a cost/benefit standpoint, you'll spend alot of money to get only a little better mileage...payback on that investment would be years down the road, if ever. You can help by getting the car as light as possible by cleaning out all the crap from the back, removing exterior items that cause wind drag such as roof racks (especially the cross-braces).

Going to high octane gas will probably get you better mileage (the car's ECM will advance timing to take advantage of the fuel's slower ignition rate), but at the expense of higher fuel cost...for +1 mpg at an extra $0.30/gal, do the math and you'll see your cost per mile increase.

cjstew4
10-29-2009, 04:53 AM
Thanks for the guidance. I will try the set of new plugs I bought first and go from there.

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