Using more petrol? Unknown reason :( Options

[Liam_c]

Hey everyone

Lately my car has been using more petrol than what it usually would, and i have no idea why.

When i bought the car, i was running it on 91 octane, and it was using about 8.5 L per 100km, and then about 2 months ago i upgraded to 95 octane and it was using 8.1L per 100km. No mater how i drove it on 95, it was doing high kms every tank i was loving it

But recently, its jumped back up to 8.5L per 100kms, and even though im driving it nicely, its still using alot of petrol. I started to notice it shortly after i had taken it on a car club run about a month ago ( driving around the hills, giving it a bit of stonk in the hills)

To some of you, this may not really be a problem, but its worrying me as i don't want it to get worse (and on my current run, it seems to be getting worse )

Where would be a good place to start looking for what could be causing this issue? I'm 90% sure it isn't a leak, as there is no noticeable marks on the ground after being parked up.

Air filter? Catalytic converter? Wrong fuel type? Fuel filter? O2 sensor?

Thanks

Engines a 3sfe.

[Box]

Spark plugs and wires if they haven't been replaced in awhile. People like to never change the fuel filter, so I'd check that too. Another thing is change in temperature can affect mileage, for most parts of the world temperatures are starting to shift one way or another this time of year.

[rentaspace]

Follow the guide on here for resetting the ECU, when I first got my car I was using 12-15L/100km, after I followed the reset guide it dropped to 11.3L/100km.

Then as box said, change fuel filter, ignition leads and spark plugs. While I was at it, I also changed my oil, oil filter and radiator fluid.
I am now using 9-9.5L/100km after these changes



EDIT:
I also use 95, but sometimes (probably once quarterly) I will use e10 to clean the inside of the tank out
When I do the e10 run I ise 12L/100km... Terrible...

The one time I used 98, I got 8.4L/100km

This post has been edited by rentaspace: Oct 8, 2013 - 6:57 AM

[Box]

I'd do the reset after the tune-up.

[bnr32celica]

tuneup time! For us americans, you're doing roughly 26mpg, which isn't great.

Also, have you checked physical timing (off the distributor) recently?

[RabidTRD]

Your upstream O2 sensor is what controls fuel trim. If it hasn't been replaced, look at that at the same time as the tune-up.

[rentaspace]

I'd do the reset after the tune-up.

usually you disconnect the battery white doing the tune up (especially when playing with fuel systems), and this should reset the ECU too

[Box]

Disconnecting the battery will reset the ECU anyhow, but it resets everything else. I'm too lazy to reset my radio so unless it's detrimental there be no power I leave the battery in place.

[rentaspace]

Disconnecting the battery will reset the ECU anyhow, but it resets everything else. I'm too lazy to reset my radio so unless it's detrimental there be no power I leave the battery in place.

I'm not too fussed on radio, as I use my phone for in-car music anyhow... Adjusting all the sound settings though, that pisses me off because every time I reset it I can never get it back to where it was... Even with the same settings it sounds different for some reason >.<

[Box]

^Exactly.

[Liam_c]

Thanks for the input guys!

I reset my ecu last night and then filled up with bp's 95 (shhh, i work for an opposition ) so ill see how this run goes.

My cars getting a WOF at work next week, so i might ask how much it will cost to get spark plugs done, filter, etc.

I've recently done an oil change, so it may or may not be having an effect... Im using magnatec 10w-40. Was like 60 bucks for 4L D: