MPG/Fuel Consumtion Issue...brainstorming ideas..???

[001Stunna]

Allright well lately after some certain issues my fuel consumption has gone to the dogs. Before i would be able to get about 340-360km by the time the needle would be at the half point. Now im lucky if i'll even get 300km by the time the needle hits half point on the gauge.

These are the things that have happened since when fuel consumtion was good to now that its ****.

-Front o2 sensor threw a car running to lean code. Got the sensors checked and front one was lazy and rear one was not working properly so both sensors got replaced with Denso FirstTime Fit Sensors.

-After the sensors got replaced the Cat was rattling, turned out the insides were loose and rattling inside so the cat was replaced with an aftermarket.

-After the cat got replaced i got a cel stating "cat is performing under threshold". I asked back at the shop where i got the cat changed and was told its just due to the size of the cat being a tad smaller. i did the sparkplug nonfouler trick and that made the CEL go away and never came back again.

-This past week whats been happening sometimes is when starting the car the rpms will go to 700-800, then start dropping lower and lower and the car shudders. At times the car will even turn off as the rpms hit 0.

-I've had passengers at times tell me that the exhaust smells like gas, and ive noticed it myself at times too. Ive checked the front o2 sensor and it is working properly and circulates from about 0.3 to 0.8.

Now the car has had its oil changed every 3000km, tranny fluid changed once a year, plugs and wires were done 2 years ago with platnium ngks and ngk wires. Air filter is new.

Only things that havent been done is cap and rotor and havent flushed coolant, power steering or brake fluid.

I read around some TSB's and even got an account at alldatadiy.com and read about a tsb regarding the fuel pressure regulator and thought that maybe thatd have something to do with it and from talking to some people ive been suggested that it might be the

-temp sensor telling the ecu the engine isnt warmed up yet and dumping too much fuel
-egr, and itd require cleaning


Any other ideas, suggestions to try out ??????



PS. Car is a 99 Accord LX+Abs - 4 cyl - sedan.

[SkylineR34X]

Lately, the temperature has also dropped quite a bit... If not totally, it would at least partially affect the fuel economy.

[jed]

Have you checked it out with some real numbers, checking with the pump and your odometer readings? I would not rely on a fuel gauge for spending money on this, but YMMV.

[kenchau]

Have you checked it out with some real numbers, checking with the pump and your odometer readings? I would not rely on a fuel gauge for spending money on this, but YMMV.

Funny, because the OP's issue is clearly on varying mileage...ha ha ha. :)
But yeah, temperature has dropped, which definitely affects mileage. Drops in temperature also affect tire pressure, so double check those to make sure they're properly inflated because tire pressure differences definitely affect mileage as well.

Also, does anyone know if gas stations have switched off of summer gas - if so, this would also affect your mileage.

[Wolfskin]

It depends on the RPM.Optimal is 2300-2500rpm, if you go higher, like 3000-3500, the car will waste much more. Same on the highway, depends on the speed.

[001Stunna]

Have you checked it out with some real numbers, checking with the pump and your odometer readings? I would not rely on a fuel gauge for spending money on this, but YMMV.
Yes actual pump numbers and km traveled were taken into reference as well.

Funny, because the OP's issue is clearly on varying mileage...ha ha ha. :)
But yeah, temperature has dropped, which definitely affects mileage. Drops in temperature also affect tire pressure, so double check those to make sure they're properly inflated because tire pressure differences definitely affect mileage as well.

Also, does anyone know if gas stations have switched off of summer gas - if so, this would also affect your mileage.

Tires are all at the same psi rating of 32~32.5.

It depends on the RPM.Optimal is 2300-2500rpm, if you go higher, like 3000-3500, the car will waste much more. Same on the highway, depends on the speed.

Well the driving style has not changed from before to now. However when noting the rpm gauge gears change at about 2400-2600 id say. Again car is pretty much driven quite smoothly and mainly sees hwy rides of about 50km daily.