I have a automatic 2009 Honda Civic and my gas mileage has gotten worse I'm only getting 200-250 a gas tank.
I changed my spark plugs and it has not changed anything.
The car is sitting at 138,000km
A lot of options checked cat converter, tire pressure, fuel injectors, brake sticking rotor, no check engine light?
Also change the air filter and clean the MAF sensor.
Btw, when was the last time you change spark plugs?
@yaser
I have changed them two weeks ago
Carbon accumulation?
@mink
How would I check for that
@mink
Use high octane gas (93) and check your gas milage. If you see improvement, your engine has carbon built up.
@mink
How do you get rid of carbon build up if it does have it?
are you burning oil? check sparkplugs, cat coverter, maf sensor, see if air filter is clogged etc.
dont let gas tank get under 20% btw... hope ur not letting it run out of gas
@jebrim
No I'm not burning oil but I did change my spark plugs last week but another thing is sometimes when I start my car the rpm's drop and they pick back up then it doesn't do it again
How do you get rid of carbon build up if it does have it?
You need open your engine if you have that problem. Just go find a mechanic like Scotty.
Just a couple things to check.
Check your CTS, Coolant Temperature Sensor, against the IAT, Intake Air Temperature Sensor, first thing in the morning before starting the engine. They should both match the outside ambient temperature.
A faulty thermostat that is not allowing the engine to reach full operating temperature.
@bc-st
isn't those sensors built into the mass airflow sensor in this car?