I purchased an 03 V6 Sport last October and on the way home (4 hr drive) the trip computer said I was getting 21.5mpg (mostly hwy). After I got it home I changed the oil and diff fluids to synthetic, new Iridium plugs, new HE air filter, cleaned MAF, and removed hydrocarbon charcoal filter from air cleaner (better airflow). After all that I'm now only getting around 20 mpg on the hwy and around 19 combined according to the computer. Any thoughts on what might have caused this drop? Wrong plugs, gas(I use 87 or 89 octane)? I don't notice any knocking or performance issues. Thanks!
MPG went down after tuneup
- Thread starter OHDAD9224
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Lexusbstrdchild
New member
how long have you drove it since you did the tune up? Maybe since you have better airflow, it will take the computer awhile to re-map the fuel/air ratio back to where it should be, and therefore is affecting the mpg for the time being?
Nuke
New member
It takes about 10-20 hand-calculated data points to truly identify any trends in fuel mileage. And that's assuming you're driving the same basic style, type of traffic, etc. each time. I've been keeping detailed mileage records for over 37 years on more than a dozen of vehicles driven over 1,000,000 miles and the variables are tremendous.
PlanetAlaska-
New member
I tend to ignore the MPG on the trip computer because I found (in my case, a 2004 and 2008) that it's not accurate. Usually too high.
charlier180
New member
I agree 110%. Trends in fuel mileage require much more than one of two data samples. WAY too many variables impact the outcome.
The original poster should do a search for all the threads about the MPG displayed by the 4Runner and it's less than accurate calculations (ie over optimistic).
In my case my '04 V8 is, on average, 13% higher than my manual calculation.
I have gas purchase/MPG spreadsheets for each of my vehicles for the last 30 years so I too have been doing this a long time.
drbiii
New member
It's nice to know I'm not the only person that does this. My wife give's me a hard time about it, but it helps to spot problems before they become headaches.
Disclaimer: Not a Toyota guy. New to forum. If removing the filter from the canister is some old tried and true TOYOTA trick, I was not aware. Link me to info on it (because I'd like to learn) and ignore what I say next.
Before the days of true EVAP systems, over 80% of HCs emitted from cars came from fuel evaporating from the tank. Hydrocarbons are pure unburnt fuel, or energy. The purpose of the canister is to catch the HCs that are evaporating from your gas tank, and then purge them into the intake manifold. In most makes, the filter inside the canister is vital to this process. Thats why its made of charcoal.
Before the days of true EVAP systems, over 80% of HCs emitted from cars came from fuel evaporating from the tank. Hydrocarbons are pure unburnt fuel, or energy. The purpose of the canister is to catch the HCs that are evaporating from your gas tank, and then purge them into the intake manifold. In most makes, the filter inside the canister is vital to this process. Thats why its made of charcoal.
DaBoostCreep
New member
Its removing a charcoal style filter that is housed in the top of the air filter box lid. Its purpose is to filter HC's after shutdown that would come from unburned fuel in the combustion chamber.
Uneek
Super Moderator
Ohhh I gotcha, Its a secondary filter in the air filter assembly. OP states that but not having a late model Toyota, I mistook him for meaning the canister filter. Thanks for the links:cowboy:
