Hey guys, since I've seen so many people complain about poor MPG (Like myself) I've decided to make a thread about it.

Here's some of the biggest things that can cause bad MPG.

- Dirty/clogged air filter.

Reason: As an air filter becomes dirty, the capacity for it to filter the air going into the engine is reduced. Because of this, the engine is not able to function properly, which may cause numerous drivability issues.

- Under inflated tires

- Lazy "Sleepy" or Faulty o2 Sensor (Check engine light will come on for a bad o2 sensor but won't for a "Sleepy o2 Sensor) This is one of the worst for bad MPG

- Foul spark plugs (Built up carbon from running rich)

- Fuel injectors might be clogged and need to be flushed should be at high kilometers or miles on the car only. (When your car engine runs, the fuel injection system will insert exact amounts of fuel into your car's engine. It combines with air within the engine and ignites in order to make your car move. If your fuel injection system isn't working properly, your car won't get enough fuel to run correctly. When your fuel injector leaks, it will waste gas, and you will use much more than you actually need. Have a trusted mechanic check your car and fix the fuel injection system if necessary.)

- Clogged PCV valve or bad Catalytic Converter

- Defective coolant temp sensor for engine computer (causes rich mixture)

Will update the list later feel free to add. Bed time

 

dirty gas filter,
dragging break (break that is not fully released)

 

LOL jason, a dirty air filter CAN NOT hurt MPG.

 

per our Federal Government :
http://www.fueleconomy.gov/feg/pdfs/...02_26_2009.pdf


Now, why would OUR Federal Government mandate auto manufactures to increase fuel economy, but then issue a false report?

its because, your claims are false, Jason

 

Air/Fuel ratio is kept CONSTANT by the ECU.

in older, carbureted engine's, there is no computer to control air/fuel ratio, thus poor fuel economy from a dirty air filter.

 

I'm with you in theory, but in practice I have seen it happen on new fuel injected cars often enough.

 

and how do you test with so many variables!?

 

Plug in an OBDII reader (or one of those USB ones for laptops + software) and check out the fuel trims (short and long). These fuel trims will tell you a lot about how much more fuel or less fuel you are using. If you see extremes + or - (say over 5) then you have some issue somewhere (maybe even too much ethanol in the gas?).

Some advanced diagnostic tools (like the Honda Diagnostic System tablet) can tell you exactly whats going on by reading the values from the 02 sensors and comparing them with the benchmark. Problem is that HDS is a bit pricey (somewhere around $2k) and good luck getting a real one (not the knock offs from China on fleabay !).

Best MPG advice for our cars... lift your foot off the gas pedal!

Just some thoughts.

 

To get an adequate reading of MPG you need to have the weight and exact power output of the car. I have an ODBII reader hooked up to a tablet in my TL which loads Torque upon bootup. It's decently accurate, not too crazy.

 

time of day, weather, tires, gas, a lot of variables play a role in determining gas mileage.

did any one read the study....?

 

How the car is driven is the biggest variable in MPG- with a modern car changing plugs and filters won't make any change in MPG so you're wasting money and time doing that if you're after MPG gains.

This wiki needs to also account for the MPH reading that the MID updates. The gauge is pretty simple- all it does is divide miles driven by hours of engine run time. Below are two scenarios:

1. running down highway for one hour @ 65 MPH -
miles driven 65 miles; MID MPH=65; MID MPG would be an estimated 32 MPG or about 2 gal / hour of run time.

2. 2/3 urban & 1/3 highway driving for 1 hour
miles driven: 40 minutes city @ 15MPH average (10 miles) + 20 minutes @ 65MPH (21 miles) so MID would read 31 MPH. The fuel burn would actually be > 2 gal but even using 2 gal as scenario #1 gives you would be 31/2 gal or 15.5 MPG

The difference that most people have is with their commutes. If you drive like scenario #1, you'll love the TL's MPG and be very happy. If you drive like scenario #2 you won't, but you need to realize it would suck for almost any non-hybrid/electric car as well. You could get a smaller motor car and save a little fuel idling at all those stop lights possibly and maybe save a little more on the highway too but it will still suck,.

Many of you will be in between and be comfortable getting 19-23 MPG like the car is rated for.