I got a sudden drastic drop of MPG in the past 2 days. The car does not give more than 15 MPG in normal city drive while it used to be between 24 and 26.
There are no fault codes. The air filter is clean, spark plugs were changed 2 years ago and coils are new. MAF senor was changed last year.
Is this the dash display that says the MPGs are low? Perhaps check that the coolant temp sensor is sending a legitimate value to the ECU. If way too cold to be true, the engine will run rich and in open-loop mode, using a lot more fuel. Any trouble starting?
Perhaps check that the coolant temp sensor is sending a legitimate value to the ECU. If way too cold to be true, the engine will run rich and in open-loop mode, using a lot more fuel.
I changed the coolant flange a few weeks back and thought to put in a new CTS. So the sensor is new but whether is working correctly is another question.
Hi Emry,
Hole in the gas tank? Have you independently verified the mpg figures. Without adding more cylinders I don't see how an otherwise healthy engine could use 50-60 percent more gas.
Not yet because I noticed this a couple of days ago. But will also verify this with a full tank. I can tell that the gas consumption has drastically increased by looking at the fuel gauge.
I'm totally puzzled too. After 18 years, I wouldn't characterize it as a healthy engine but it ain't sick either. It has some benign illnesses but still breathing.
I would clean or replace you intake air temp. sensor, There was post that said this responsible for how rich or lean your engine will run. it is on the side and by the throttle body new cost 18 dollars.
I'll add more things to check:
Might be good to peek at one of the spark plugs to see if they are black.
i just changed a badly clogged catalytic converter that reduced power and mpg. I took out the pre-cat (B1S1) Oxygen Sensor and noted excess pressure out of its hole when the engine was running. I also peeked inside that 02 hole with a small USB camera.
A fuel leak maybe near the fuel filter?
Thermostat stuck open and engine is not maintaining the normal operating temperature.
Cleaned the air intake temp sensor but nothing major happened.
Here's another weird thing happening that I cannot explain. When I use the tip the MPG is very normal around 24 but when it's in auto mode it drops to 15.
Use your laptop to watch gear changes while driving, looking for it to not be going into fifth, for instance, when in auto mode.
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