Extremely Bad Gas Mileage

The mpg displayed by the car is calculated using fuel curves/pressure/injector duration/all those fancy things floating around in the ECU/etc. Considering the car's electronics are still showing normal mpg, yet actual miles per tank are extremely low (yet fill volume is normal........I would focus some attention on looking for a fuel leak.

Know what I mean? The engine IS getting 45 mpg, it's just that only half of the gas in the tank is going to the engine. The rest is going onto the ground or into the air.......maybe....

 

fill the tank, reset the trip meter, drive until the last pip, refill and divide miles by gallons pumped and report back

 

There ya go, gettin' all logical. Again.

I have to agree with this. If the car says it's getting 45 mpg, then that's what the engine is getting. Well, almost 45 anyway. If you're putting 8-9 gallons in the tank to go 160 miles, then obviously, most of the gas isn't reaching the engine. I would think that that would cause a big stink. Literally.

 

Maddie????

Hope you were able to resolve the problem. Yes or no, please let us know. The more feedback that gets posted, the better our "well of knowledge" becomes.

 

Those don't effect fuel economy.

 

Those Gen 2 gas tank bladders got you by reducing the amount of fuel you can put in the tank and on top of that cold weather makes it seem much worse than it is.

 

I'm sorry tideland, a dirty air filter does not effect fuel economy. To be politically correct is to not correct you so I'm not going to be politically correct but I'm also not going to put it in a lot of time trying to teach you this one. You're going to have to teach this one to yourself I'm sorry. the same token that cannot let you propagate false information as though it were correct just because it is your belief system.

I'm an ase-certified mechanic and a practice medicine now because I went to school for a long time so I didn't have to be a mechanic anymore. You need to learn what a mass airflow sensor is. You need to learn how the system adjusts to the amount of air that goes through so that the fuel ratio remains constant no matter how dirty and air filter is. an oxygen sensor monitors to confirm that the fuel ratio is stoichiometric. The mass airflow sensor recognizes the correct amount of air flow even if the throttle vane is wide open but the air filter is kind of dirty.

 

Unsubscribed from this topic because I don't feel I'm learning anything here.

 

Poor @MaddieS! I think you guys ran her off. I wonder if she's still only getting 160 miles on 8 or 9 gallons of gas. Remember the original question?

I hope she comes back, because with enough info, there's a good chance someone like @TMR-JWAP can point her in the right direction.

 

You're right about that. I've found diagnostic suggestions don't often get result in success when done by text messages. The person with hands on the problem needs to be armed with knowledge plus tools plus wisdom and much of that comes from experience. As listeners we attempt to guide the diagnostics but it doesn't always help unfortunately.

most of all after somebody has solved the problem they don't follow up and give us the answer to what they discovered. There's often no closure. This is where we all can benefit from this discourse but many times do not. Hopefully she does respond so that we can add this causative agent as a differential for the next person who has a similar problem.

 

You are comparing "miles per TANK" and "miles per GALLON", those measures do not measure the same thing. If you used cost per mile, that would likely be the same no matter how much or little fuel you put it during refueling.

MPG = Miles driven / gallons used (# off the pump)

MPT = Miles driven before you fill (could be 1 or 500) which has nothing to do with MPG.

 

If the engine can't breathe the way it was designed I'm sure it would affect fuel economy.

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Actually, it does, but the effect is so small most could not measure it. The ECM injects the EXACTLY correct amount of fuel for the air that does get in and not a drop more. Power can be significantly affected by a plugged air filter, that is proven and why race cars do not have them.

 

Yes but if you noticed a power difference you would notice a milage difference. But it would need to be plugged. Lol

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now that doug is no longer here, i'm sticking with 'clogged air filter affects fuel economy'

and if i get sick in florida, i hope that's his real first name

not tobe pedantic or anything

 

The only apparent problem is the low miles-per-tank, which (as @Tideland Prius first noted) is likely due to the 2nd gen tank having a "flexible" bladder, which can contract/restrict.

The dash display is saying 45 mpg, which is good. I wouldn't quite believe it, but only because Toyota likes to BS the displayed mpg, about as much as they can get away without it becoming blatantly embarrassing. Actually, I think they've crossed that line, have no pride, lol.

Instead of just believing or not: calculate it, see for yourself. At every fill up, record the gallons of gas put in, and the miles since last fill up. Divide the gallons into the miles; that's your miles-per-gallon (mpg)

My understanding from what I've read: that used to hold true in the manually tuned carburetor days, but with computer controlled fuel-injection, with sensors detecting the air flow, the amount of O2 in the exhaust, knocking, fine-tuning the injector sprays accordingly, you can be running low octane and a dirty air filter, still do fine.

In fact a partially clogged air filter might improve mpg, you're sorta reducing the engine displacement, the volume of air. I've heard the only time air filter clogging matter is if it's virtually blocked.