im facing issue, very LOW Gas Mileage, 3days ago filled the tank full, till now driven 210km and tank is empty.
what can be reason for low mileage,

its running like 3km/ liter (supposed to be 8km/L atleast)

 

How many miles/km on the odometer? What had the maintenance been like? When was the last service and what was performed? Who takes care of the car repairs?

Too many possibilities.

Check the basics:

0. Do you have a check engine light?

0.5 Check the engine oil for color and level

1. Idle the engine and listen for air hissing sounds around the air filter and throttle body.

1.5 does the coolant temp gauge reach just below the middle point? If it stays lower than that after 5-10 minutes of driving, then the engine is too cold and it will consume a lot of gas to try to warm itself up.

2. search for disconnected electrical plugs

3. Search for broken or disconnected engine hoses

3.5 inspect the air intake hoses for crack. Squeeze them and look underneath with a mirror

4. check your tire pressure

5. check your brakes for rolling resistance. Does the car feel like it’s slowing down too fast while coasting? Are the rotors very dark?

6. Check the transmission fluid

7. Count the gears to make sure it shifts to 4th gear while cruising and that you’re in D

8. check and clean the MAF sensor with special MAF cleaner only!


Do you have an OBD2 scanner that can also read live data?

Make sure the coolant temp is between 180-200 while driving around.

I would check for fuel trim numbers when the coolant level gets to 180F.

Total fuel trim per bank should be less than 10%.

Check the voltage readings for all Air Fuel and Oxygen sensors.

B1S1 and B2S1 are called Air Fuel Sensors and should be fluctuating between 0-5 volts but stay closer to the middle which is around 3volts. If they’re stuck on 5volts or 0volts, you’ve got a problem. If they don’t change when you give it gas, you’ve got a problem. If they take a long time to recover after you change the RPM, you’ve got a problem.

B1S2 is the rear oxygen sensor. It should be between 0.1 and 0.9 volts and going up and down like a wave on a graph. If it’s stuck on 0 or 1, it’s bad. Or you could have a giant air leak or a bad fuel problem.

if you’re struggling, take it to a shop they know all of this and can do it quickly.