Mileage Concern
 

hey all, i drive a acura integra.

Up until about November or so, it had been getting between 450-500km/tank (tank is 40-45litres).

Now lately ive been getting a solid 350/tank.

I did some calculations and i think that works out to 18mpg. The car should be getting around 28-35mpg.

The motor is a B18b (1.8L inline 4cyln). Besides the gas mileage, i cant tell any difference. Runs like a clock. No problems at all.

So, winter has just hit us, could that have any affect? I drive this everyday about 15-20km.

Anything I can check, as to what is going on?

edit: the car is bone dry stock

Well colder air will certainly affect your gas mileage, but you seem to be suffering more than just from the cold. I'd start by checking fuel filter, air filter, spark plugs, wires, and ignition timing. If that didn't yield any results, I'd look at compression - if one of your cyls has low compression that'll do it.

look for fuel system leaks, try to check all lines, near filters, and around the injectors.

Shak is onto the right track - definitely check your filters first, but geeze, that's a pretty severe drop for just a filter problem.

Yeah, I'm gonna guess at something leaking in the fuel system, and/or a sensor gone bad, or possibly even so far as an ECM taking a shit. If that happened, you'd lose mileage, and have all sorts of issues that you MAY NOT notice, and it still wouldn't set a check engine light.

I would defently look into the 02 sensor and go through the typical "tune up" stuff. When was the last time you did plugs, wiries, air filter, fuel filter, cap, rotor etc. etc.?

Some places in smog areas change to oxygenated fuels around this time of year, and the fuels have a lower energy content per gallon compared to normal gasoline so the engine has to richen the mixture to maintain proper air fuel ratio so mileage decreases. It might just be that, in which case there isn't anything that you can do until spring.

well here's a little update.

The coolant was terrible, brownish with white corrosion'ish type stuff. Anyways, I bought the car not to long ago, so I dont know exactly what was done, and when.

So, I flushed the rad real well, got some nice new coolant, then replaced the fuel filter and the air filter. The old air filter was fairly dirty, and looked like it may of been a part of the problem.

Just filled the tank w/ gas, so ill let you guys know how she's doing.

Btw, for suggestions like, the ECU, and injectors and plugs, wouldnt i feel some sort of decrease in performance, or instablility in the engine?

The car idles like a rock, starts and runs great. Much better then any car ive driven. (Limited experience), But fingers crossed, what I changed was the problem causer.