Mileage per tank dropping?

[Kreuger]

Hey guys, Im new here. Found the site on Google, looking for info about doing a tuneup on my car (looking to find if out about plugs and wires because my dad said distributor cap means theres wires but all the info Ive found said there isnt). I have an '04 Corolla CE which I bought used in June 2010. Anyway, the last few months I've noticed Im not getting as many KM per tank as I used to get. I used to get around 500km/tank even in the winter which it normally drops due to warming up the car and such. Now I barely pass 400. I've done an oil change and changed the air filter as well but it isn't making a difference. I haven't done a tuneup on the car since I got it and my dad said that was probably why. So Im wondering if there's anything else that might be a culprit, if a tuneup doesnt help? In the summer I enjoyed over 600km/tank which is great but with the price of gas these days I need to try and stretch each tank as much as possible. One difference now though is Im no longer doing highway driving for work. I'm going half as far since I switched jobs but at least 10 minutes of my drive is city driving and the other 5-10 is on the back roads. The car is coming up on 160k on the odometer. If you require anymore info, just ask. Thanks!

Edit: Also there seems to be an issue with the lights in my dash/console. They frequently go dim and even off (mainly the ac/heat one) and I can get it back by tapping on the side of the console. However last weekend I got in the car and flicked on my lights on the dash and it didnt even light up. However, they've since come back. I haven't pulled anything apart on it so Im assuming a fuse is probably going?

[johnoh]

the roads you drive and the number of stop lights you idle at both have a huge impact on your km/tank, so that may be the only reason for the drop-off. Regardless, its good to tune up the car at 160000km if you have not yet done so. I would replace the spark plugs and clean the mass airflow sensor (maf) for starters. Your car has neither a distributor cap nor spark plug wires - it uses a coil-on-plug technology instead. Others will also pitch in I'm sure.

Also, its not a big fuel economy item but its possible that you are still on your original transmission fluid. A simple drain and fill every 30k will keep it fresh, and you can do it yourself. Do some searches in this forum for procedures on doing that and also your plugs, plus whatever anyone else says.

[Kreuger]

Well I just had a look at the plugs, they aren't as bad as I expected but Ill be doing them soon. Also, my brother just bought cleaner to do his maf so Ill get it and do mine as well. He was having issues with his rpms and stalling so he did that but since my only issue was gas mileage, I wasnt gonna bother. Now that you recommended it, I will.

One thing I noticed that confused me is the lid on my power steering fluid spout where you add more, it says power steering but it says use Dexrod ATF. Why would it say to use tranny fluid but also say that it's power steering? By the way, I considered having a flush done but Ive heard too many bad things about it, so I figured if I just drain it and add more myself it would be fine.

Thanks for the suggestions, so far

Edit: We took it apart and it looked pretty clean, especially the butterfly valve. It was a bit dirty on the inside but not too bad. I guess Ill have to just chalk it up to the difference in driving. Its a lot more stop and go for me now.

Edit 2: Looked at the dipstick for the tranny fluid and it looks pretty clean. I still dont understand the problem above though.

[boberic]

Most cars use some kind of auto transmission fluid for the power steering system. Also, it is probably a waste of time to flush or replace that. It doesn't get hot like most other oils in use on the car, so the fluid doesn't degrade much over time.

To give two examples, engine and transmission oils get warm because so many metal parts are sliding and otherwise moving against each other--and of course the engine is going to get hotter still due to the fuel burning.

[hardtopte72]

As far as your lighting goes you may be experiencing a bad connection (either at the connector or internally at the circuit board).

As for your mileage on top of the differences in driving in these cold winter months the one biggest thing people neglect is their tire pressures. As the temperature goes down the tire pressure drops. Lower tire pressures results in a hit to overall MPG's. When I used to work at Toyota everyday in the winter months somebody would come in with a Tire light on. And the people who didn't the vast majority has less than 25 PSI. Some people would come in with less than 20 PSI and they had no idea. Check your tire pressure, change the spark plugs with OEM plugs or NGK Iridium and go from there.

Some tips that may help too is avoid the defroster/defogger when driving as this automatically cycles the A/C compressor. Combined with stop and go it is a domino effect for fuel economy.

[Kreuger]

Most cars use some kind of auto transmission fluid for the power steering system. Also, it is probably a waste of time to flush or replace that. It doesn't get hot like most other oils in use on the car, so the fluid doesn't degrade much over time

Well I noticed it was low anyway. So am I looking for Power Steering fluid to top it up or ATF?

As for your mileage on top of the differences in driving in these cold winter months the one biggest thing people neglect is their tire pressures. As the temperature goes down the tire pressure drops. Lower tire pressures results in a hit to overall MPG's. When I used to work at Toyota everyday in the winter months somebody would come in with a Tire light on. And the people who didn't the vast majority has less than 25 PSI

I don't have any light for my tires but from what I've seen they're still full. And apparently my winters are nitrogen filled. Apparently Canadian Tire did that when they swapped my tires.

Check your tire pressure, change the spark plugs with OEM plugs or NGK Iridium and go from there.

The plugs in it are NGK but they didn't look as bad as I expected. I found it funny that the Toyota dealer would use NGK plugs. All work done prior to me buying it was done by the dealer AFAIK, Ill have a look through the maintenance thing that came with the car to see.

Some tips that may help too is avoid the defroster/defogger when driving as this automatically cycles the A/C compressor. Combined with stop and go it is a domino effect for fuel economy.

I usually drive with the heat on the windows (on the lowest setting) just to keep them clear and also so I dont get too hot myself haha. I guess that's probably bad?

[hardtopte72]

Originally Posted by Kreuger

Well I noticed it was low anyway. So am I looking for Power Steering fluid to top it up or ATF?
I don't have any light for my tires but from what I've seen they're still full. And apparently my winters are nitrogen filled. Apparently Canadian Tire did that when they swapped my tires.

The plugs in it are NGK but they didn't look as bad as I expected. I found it funny that the Toyota dealer would use NGK plugs. All work done prior to me buying it was done by the dealer AFAIK, Ill have a look through the maintenance thing that came with the car to see.

I usually drive with the heat on the windows (on the lowest setting) just to keep them clear and also so I dont get too hot myself haha. I guess that's probably bad?

Nitrogen is a joke. My dealership had a nitrogen machine too. The dealership would tack on a 175 dollar fee for nitrogen in your tires on a new car and to do the service for a regular customer. And guess what in all my experience (hundreds of cars) the stuff would lower tire pressure just like air (I had it in all of my cars). It did not cause less dry rot, or last longer, or be impervious to temperature changes (air is 78% nitrogen as it is, the nitrogen machine requires air to work, and the lowest it gets the air down to was 6 psi before it "filled it". You need to check your tire pressure with a a gauge not by sight. Nitrogen works in Nascar not in a car driven daily.

And yes if you use the defroster on the windshield it is cycling the A/C compressor so it is just like using the A/C. Factor that in to your driving.

[GREENPUS]

Originally Posted by hardtopte72

As for your mileage on top of the differences in driving in these cold winter months the one biggest thing people neglect is their tire pressures. As the temperature goes down the tire pressure drops. Lower tire pressures results in a hit to overall MPG's.

This plus cars usually get less mpg in colder months anyway. Also when the defroster is running, the ac compressor is also running to lower humidiy in the car. This also lowers mpg.
I get around 40mpg in summer but in winter it dropped to around 34mpg. When i turn off the defroster, my mileage goes up in the winter.

[Kreuger]

Nitrogen is a joke. My dealership had a nitrogen machine too. The dealership would tack on a 175 dollar fee for nitrogen in your tires on a new car and to do the service for a regular customer

Well it wasn't a dealer and it certainly wasn't my choice but if they did it for free (which they did because it was the same price they always charge for a tire swap) then I won't complain.

My main concern about the mileage is that last winter I only lost about 80km a tank. This year it seems to have almost doubled. But I digress (again), I'm doing more city driving. Thanks for the help everyone. Gonna do my first oil change on this car this weekend. Been a while since I've done one, at all. Should be fun.

[MasterTecInSTL]

Originally Posted by Kreuger

Well it wasn't a dealer and it certainly wasn't my choice but if they did it for free (which they did because it was the same price they always charge for a tire swap) then I won't complain.

The thing about nitrogen is that pure nitrogen in the tires is definitely better than regular air.. but the question is "is it really needed?"

In my opinion.. no. If it's free then by all means go for it but do not pay extra for this service.

Also many people I've met that have nitrogen seem to think that it makes their tires bulletproof. One elderly man thought that because he had nitrogen made it so he didn't have to check his tires and he refused to believe me when I told him his tires were grossly under inflated and would not let me put air in his tires even though they were down to 15PSI! It ended up becoming an argument because I told him to take it straight to the dealer to have it filled back up with nitrogen but he kept insisting that it must be OK.

Having pure nitrogen in tires does have its benefits but nothing that is even really beneficial for normal driving conditions.

[hardtopte72]

Originally Posted by MasterTecInSTL

The thing about nitrogen is that pure nitrogen in the tires is definitely better than regular air.. but the question is "is it really needed?"

In my opinion.. no. If it's free then by all means go for it but do not pay extra for this service.

Also many people I've met that have nitrogen seem to think that it makes their tires bulletproof. One elderly man thought that because he had nitrogen made it so he didn't have to check his tires and he refused to believe me when I told him his tires were grossly under inflated and would not let me put air in his tires even though they were down to 15PSI! It ended up becoming an argument because I told him to take it straight to the dealer to have it filled back up with nitrogen but he kept insisting that it must be OK.

Having pure nitrogen in tires does have its benefits but nothing that is even really beneficial for normal driving conditions.

Right it may be good for Nascar but not the average Joe. It dissipated in 2 of my cars at the same rate or faster than regular air. And down here my tires would have long been worn out before I had any dry rot that the nitrogen could prevent (on the inside of the tires as most tire failing dry rot still occurs outside the tire anyway). It is just not necessary at all to use. If it was free more power to you but still check it like air.