2008 toyota tacoma fuel mileage has dropped

08 Tacoma 4 cyl . 2.7 cc
I noticed that the MAP has a cloth filter, can that filter be cleanned? Is there a spray I can use without damaging the MAP?
No red light.
Other than spark plugs, is there anything that others have found to work?
Would the gas recirculation canister affect gas mileage. How can I test it?

Can you define your fuel mileage drop? Has it gone from, say, 20 MPG to 10?

You don’t mention your mileage. My experience is that at about 200K any engine’s combustion chamber will start to leak, evidenced by more blow by and dirtier oil and translating into less power for the same amount of fuel. Personally I wouldn’t try to clean any engine sensor or fixate on any one. I have had sensors go bad without triggering a MIL, most recently an O2 sensor, but confirm the sensor is out of spec with a scanner before random replacement.

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If the coolant temp is taking a really long time to come up to full temperature or never actually getting there, that would cause poor fuel economy.

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+1 to Mustangman’s suggestion. Could be a sticky thermostat.
I replace the thermostat every 10 years, so it’s overdue IMHO.
OEM, not aftermarket. Radiator cap too.


New tires? Even if the same size, they are often heavier because they haven’t worn down. And tires vary in rolling resistance. Tire inflation up to spec?

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Yes. Michelin doesn’t make the 215s any more and had to step up to 225s. Not a big change.

My mileage over the years has dropped from 26 to 24 to 22 and now to 19mpg city.
I figure gear ratio of new tires is probably 3 to 5 percent more so even with that factor it doesn’t acct for the declining drop in mpg.
Can it be something as simple as a overflow evaporator canister issue?
How would I test for simple issues? Catalytic converters?
Thanks for your help!

Sorry, I have approx 130k on it.
Miles dropped drop from 26 new to 24 to 22 and now 19.
I check the codes and report back.

Your Tacoma was rated 20 MPG city and 25 MPG highway . I can’t see you ever getting 26 on strictly city driving . The 19 is more like what you should be getting . How are you checking the miles per gallon ?
The 225 number is the width not the diameter .

The 4 cylinder Tacoma is rated at 19 MPG for the automatic transmission, 20 MPG for the manual, I doubt there is anything that needs to be repaired.

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Ok I was wrong about tire size , I went from 215/70 15 to 215/75 15. What I call city is actually a combo of city and highway. I drive from San Jose to Aptos. So there’s hwy17 in off commute hours and city San Jose and Aptos.
I set travel odometer at fillup and check after gallons of fuel and miles driven.
Maybe I’ve been spoiled all this time with mileage.

If your charcoal canister was at fault it would illuminate your CEL.


At 19 mpg you are where you are supposed to be. Hard to believe you ever got 26. I’m with Nevada545, I don’t think there’s anything wrong with it unless it continues to decline.

Would be unusual for a cat to clog at 135K. You only mention mileage loss, not power. A clogged cat would make itself known by loss of power, especially passing or uphill. Not that the Toyota 2.7 had a lot of excess power to begin with.

I found a scanner which said I don’t have any codes.
One curious item, the alternator output is riding around 13.4 to sometimes around 13.6 volts. A mechanic said it shouldn’t fall below 14 volts.
Is the alternator constantly demanding hp from the engine by running a trickle charge or is this a normal operation.

Slightly low battery voltage will not reduce fuel mileage, actually the opposite.
13.4V is okay, especially in hot weather.
Did you look at engine temperature with this scanner?
Have you changed the thermostat?

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Without any engine codes and no other symptoms, unless the mileage continues to fall I don’t think there is anything wrong that can be corrected. You could check for dragging brake shoes and pads and tire pressure, maybe even add a couple of pounds, and the alignment should have been checked when you got your tires. Otherwise you are experiencing the rated mpg. The alternator output is maybe a tad low but good enough to keep the battery charged and with no impact on your gas mileage.

Thanks for the reply… I’ll continue monitoring the mileage and recheck alignment and breaks. The mpg has stabilized for city around 19 to 20 which I now realize is ok. Unless anything dramatic happens I’ll discontinue this conversation. Thanks to everyone for their insights.

Temps good.