Bad fuel economy

[Yaris2468]

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[Yaris2468]

Also there is a lot of black carbon deposit in the exhaust. When I showed them at Toyota they said its normal though.

[SAV912]

Is it a regular occurence or was it 400 KM on one particular tank?

If it was just one tank, it could be an anomaly. Bad winter gas, cold winter conditions, a particularly high amount of city driving...it adds up.

If it is ongoing, I'd recommend cleaning off the MAF and throttle body. That will complement the air filter and spark plugs. Possibly switch to full synthetic (5w/30, I run 0w/20 but that might be too thin for Canada) oil as well.

-C

[Yaris2468]

Its been about 4 tanks like that. very consistent. I was told synthetic isn't the best for my car overall. the MAF and throttle body.. can I do that myself or does a mechanic?

[SAV912]

The MAF is very easy to do, you just have to be very careful handling it. Two screws, a paper towel to sit it on, and time. That's all you need. The throttle body is a bit more difficult, but there are plenty of Do It Yourself/How Tos listed in the DIY Maintenance forum. As far as how consistent this is, I'd still be inclined to chalk it up to winter blends and cold temperatures. Of course, I can't say that is 100% your only reason.

Whoever told you synthetic wasn't the best for our cars is full of tartar sauce. The ONLY reason you wouldn't run synthetic is if you car is very old and has a ton of miles. Syn can loosen bits of sludge that have otherwise plugged a potential leak. But even an '07 shouldn't be that old that synthetic would pose a problem. I'd get it switched over pronto. It's a bit more expensive to run synthetic but the returns in fuel mileage and overall performance balance it out in your favor. I've run Mobil 1 FE 0W/20 the entire time I've owned mine, more than two years now. Hope this helps. :drinking:

-C

[daf62757]

I just went through a rough stretch of bad mileage. I started using Lucas fuel additive again and my MPG average went from 33 mpg to 40 mpg. You have to be consistent in your use and always have a bottle ready to pour into the tank.

[SAV912]

SeaFoam would also likely help, if there are carbon deposits in the exhaust. It is a delicate procedure though and I wouldn't recommend doing the vacuum line portion without a buddy to help out.

-C

[caper26]

I just went through a rough stretch of bad mileage. I started using Lucas fuel additive again and my MPG average went from 33 mpg to 40 mpg. You have to be consistent in your use and always have a bottle ready to pour into the tank.

Which one of [THESE (http://www.lucasoil.com/products/display_products_overviews.sd?iid=5&catid=6)] do you use??

[daf62757]

Which one of [THESE (http://www.lucasoil.com/products/display_products_overviews.sd?iid=5&catid=6)] do you use??

I use the middle one. The Lucas fuel treatment. I buy it in the gallon jug to save money.

One thing I have noticed is that Lucas had a genius to make the fuel treatment, but a complete moron to design the plastic bottles they come in. Every size I have bought leaks and causes a mess. I have wound up buying two small bottles and pouring the gallon jug into these smaller bottles and using them as I go.

[caper26]

Excellent. Got my summer tires on today and a bottle of the FT, and will fuel up shortly and dump a bottle in the tank and see what happens!! Temp supposed to be up for next few days too (over 20 C)

[caper26]

Also cleaned the MAF sensor and vacuumed out the intake box and air filter

[curtmaxwall]

There are lots of reasons behind the bad fuel economy. There are all system parts contributing in bad fuel economy due to their bad behaviors or lack of maintenance. The first thing would be the Air fuel ratio sensor, catalytic converter, oxygen sensor and rust in air filter and fuel filter. Maintain all fuel supply system parts in proper manner including fuel filter, fuel pump, fuel sensor etc.

[caper26]

Car has only been on the road 1 year with 13,000 km. I hope nothing else is wrong besides what has been mentioned.

[caper26]

I did some things are initially getting drastic results, but may be due to outside temps as well. check my thread 600/450 km in the FE forum if interested.