Curious about my rather High fuel consumption

[officersheepdog]

Hello all, I'll give a very brief overview of my car and its service life.

Year: 2008.5
49,018kms
Engine: 2.3L
Oil change every 4,000km
Auto Transmission fluid just changed last month.
Air filter changed 3 months ago
Car is USING winter tires on clear dry pavement during testing weeks.
Muffler delete, so straight pipe in place of it. Still have all other items, Ex. Resonator etc..


Ok, So im using 14L of fuel for every 100km of road.
I found this very high so i slowed right down, to grandma speed, and got 13.5L

So I reset the ecu, and drove it for 1 week very fuel efficiently, and went right back up to 13.5L

I tried again, a month later (temps were slightly warmer same road conditions Clear), and got 13L so we will say on average 13.2 my car tells me i am at 13.2 right now.

I did a 78 km Highway only test and scored 8.1L / 100km
drove 18 km on the city roads as fuel efficiently as i could (Barrie not crazy Toronto =D ) and it went to 12 the next day mixed highway and city and it was at 12.8. As i mentioned before i am back at 13.2L

So whats the deal? do i need to change sparks?
Just before anyone mentions it.
I talked with 2 mechanics before installing the straight pipe and they told me if anything ill suffer from 1-2% gain or loss of power, that is all. It will not burn valves of a EFI engine. And that is has more than enough back pressure on its own, OK that's cleared up

Please any help is greatly appreciated.

Yes i have used those fuel cleaners many times, would anyone recommend doing sea foam? Or do I have other things to worry about?

Regards,
Tim

[officersheepdog]

Ughh replying to my own new thread.....tsk tsk where is edit function.

The reason I ask is because I have had good fuel consumption of 10L-11L/100km driving spiritedly on my daily drive to work and back. well actually i drive fast, all the freakin time.
Now ever since this winter Im getting 13L+ driving slowly and 14+ driving normally. During the same route!

[bman13]

Currently, YOU WILL have horrible fuel economy due to winter. Check tire pressure...but regardless, winter you're going to have shittier fuel economy...that's just the way it is.

In summer, depends on your overall driving pattern...city vs. hwy...aggressive vs. grandma, hard stops, etc.

[officersheepdog]

Of course winter will cause higher consumption, i guess i was not clear.

This is on a average winter for me (This is the cars 3rd winter which is almost over thank the heavens) and i got 10-11L/100km

Now this winter i get 14km driving the same way i always do, and when i try to be good for weeks on end, i get 13.2L just seems way to drastic of a change.

Normally i got 500km per tank before i usually filled up being close to empty.
Now i get 400km if im lucky, usually around 380km or so per tank. Which i think SUCKS!

Anyways thanks again.

[Pokey]

Shouldn't the 2.3 get about 8L/100km in the summer on average? 13 even in the winter is nuts! It's the middle of winter and I'm getting just over 7 (2005 2.0).

Maybe that's why Mazdas new engines will be 30% more efficient - it won't be very hard getting there when you start at 13L/100Km.

I have all seasons, and keep it below 3000 for the most part.

[SomeGuy]

There is definitely something wrong with your car...I drive a MS3, 100% city and am getting 13l/100km across several tanks and I'm on snows and I am not afraid of the boost.

Could be a million different things, tire pressure, spark plugs, electrical something or other, driving habits, intake something, wheel bearings even...who knows. I would take it in for a thorough inspection at mazda, especially since you might still have some warranty left.

[Elusivellama]

You know, I'm wondering if we're actually getting the amount of gasoline we're paying for at the pump, as opposed to the other additives and crap they put in during the winter months. Recent world events driving oil prices high and all that.

[officersheepdog]

You know, I'm wondering if we're actually getting the amount of gasoline we're paying for at the pump, as opposed to the other additives and crap they put in during the winter months. Recent world events driving oil prices high and all that.

That's something i've been thinking about for awhile, but more people should have noticed if that were the case. Either way, I will be filling up the empty tank with premium today....even with these absolute shit prices. 1.34 for premium ;(

Ill let you all know what i averaged, and other details after that tank is done.
Should be around a week or two for me to do this.

Please keep posting ideas, I am quite knowledgeable on cars, and understand it could be 1 of 100's of things. That's why the Idea's and posts help so much !

[shu5892001]

Try to inflate your winter tires to 38 psi, it helped me boost my fuel economy

[Elusivellama]

My winters are inflated to 41 front, 40 back. The max cold tire pressure of my tires are 44, and the recommended pressures on the door sticker are 35 front, 34 back (the manual says to add about 5 psi over the recommended pressures when running winter tires).

I'm not sure that 91 - 94 octane is going to help your fuel economy, higher octane blends are formulated for engines that run higher compression ratios. The higher the octane, the less likely the fuel/air mixture is going to pre-detonate in the cylinders when the pistons compress it. Since your car was designed to run on 87 octane, higher octane does nothing for you except drain your wallet. But maybe try using Shell gas with their nitrogen-enriched stuff.... long shot, I'm not sure that stuff will magically fix your fuel economy. It's still worth switching gas stations to see if another brand is better for you. I would not be surprised if we start hearing of fuel doctoring and other shady stuff that's a side effect of the unrest in those oil-producing countries.

[iratetechie]

Ok this is going to be a real mashed reply.... I agree with Elusivellama, I dont think we are getting the amount of fuel at the pumps regardless of the season. This is not gospel or fact this is what I have been told.... Regular fuel I think someone once told me (a chemical technician) there was enough gas just to run the vehicle. There are sooo many additives and cleaners in the fuel she is surprized that cars run. (And don't get me started on the cost of gas!!!) As you go up grades then there is more "gas" in the fuel due to federal laws. In honesty, again this is what I am told and if it does not have a computer chip or anything to do with computers... I am screwed on remembering....

As for fuel consumption... I just bought my first 2011 Mazda 3 (yes I am a Mazda Virgin) and I am getting real shitty KM's out of it. I have now gone 2 tanks with an average of 450KM on each tank. I do a lot of hwy travelling since I commute 70KM to work each day. I usually do 110 on the highway and leave it at that. I try to keep the prm down as well below 3000. Well new car anyway I should not be going over that... I would say I am a 70/30 split on hwy/city driving..

So going on what I did on my last older vehicle I was getting 600 average on a tank... however I kept up my plugs changed every 40,000 and made sure all air intakes were clean and free from things like dirt, tree twirlies, animals (yes I found a dead frog in my air intake when I changed the air filter) And every third tank was premium as well as changed the fuel filter every second year (as long as it is easy to get too, or you know an auto mechanic that owes you huge!!!). I usually used Wynns engine cleaner once a year with a premium fillup and before a trip to burn it on the hwy. Winter I was averaging just under 600... and I always have all season tires from Canadian Tire. (which I still stick with since I get about 100,000KM on there cheepies)

sorry just my two cents, hope it helps...

[notthesnail]

It seems a bit premature, but an out of spec front O2 sensor can result in burning more fuel without throwing a code for a bad sensor. These sensors lose resolution over time, but you should get at least triple the milage you posted out of one. The only problem is they're usually expensive, especially in the Great White North. For my (other auto maker), local prices were $330 to $400+, even for a 'universal' fit. Amazon.com sells the OEM fit Bosch for $85. CBI for the win!

[jewopi]

I just tested my 05 mazda3 for gas consumption and got 420km's from full to just over empty, I have the 2 liter engine and its 5 speed, with winters on it. gonna test it again come summer time with the 17 inch MSR's on it and see what it can do.

[officersheepdog]

OK so I must admit I did not think about tire pressure, yet results are the same (Nearly)

Tire pressure for winters was at 31 - 30 rears and 33 - 35 fronts, so i now have them set at Fronts = 41 both and Rears = 38 Both

It has been raining so roads have been wet rather than dry, and to my surprize..... Fuel consumption from 13.2 is now 13.3L

Dubya Tea Eff..... Im just going to drive the shit out of it like I want to and get 14L/ 100km while having fun.

I will seafoam in Spring or whenever warm enough to do so. I'll post results of my fuel consumption after and a Youtube video of the actual cleaning.
I hope seafoam lives up to its name, more than that i hope its just carbon clogging my engine and not a O2 sensor burning fuel like someone else mentioned.

[laksman91]

you're running a straight pipe? No cats no muffler?

[officersheepdog]

Everything is in place except the muffler, so the cats, resonator they are all still there.

[Nutella]

I had this problem with another old car ('97 RAV4). Sucked gas around 16L/100km. No symptoms, no real power loss notice. No idea what was wrong. Sold it like that to some poor bastard!

My best guess is that it's most likely related to fuel system and sensors. O2, MAF, MAP?, injector(s) gummed up, compression down on 1+ cyls.

Question: how are you measuring mileage? I do it by Trip Odom kms / Litres at next fillup. I consistently get 9.5-10L/100km on a Protege5.

I feel your frustration!

[officersheepdog]

I had this problem with another old car ('97 RAV4). Sucked gas around 16L/100km. No symptoms, no real power loss notice. No idea what was wrong. Sold it like that to some poor bastard!

My best guess is that it's most likely related to fuel system and sensors. O2, MAF, MAP?, injector(s) gummed up, compression down on 1+ cyls.

Question: how are you measuring mileage? I do it by Trip Odom kms / Litres at next fillup. I consistently get 9.5-10L/100km on a Protege5.

I feel your frustration!

Haha thank you, yes same thing no power loss at all, or noticeable it feels PERFECT! But the gas mileage is measured by how far i get on a tank, which is 380km per tank, and the 13.2L/100km i gave is by the trip computers own measurements.

Which last year when the car was 2 years old in winter with same tires was 460-490km per tank and trips computer @ 10.x/100km

Just a question if i seafoam the gas tank I should not need an oil change yes>?
I am almost certain this is the case, but wouldn't mind some one else's opinion.

Btw my trips computer now reads 13.8L/100km *Sigh*

[Pokey]

^^ measure your own milage ( L/km *100)

[mazdabetty]

Which last year when the car was 2 years old in winter with same tires was 460-490km per tank and trips computer

Yeah, it sucks... that's about what I was getting city driving for the past 2 years. Highway about 600+ (didn't really notice that big of a difference from winter to summer to be honest like everyone keeps saying here)...

Not even close now, I get under 400/tank I just filled up last night after being told that my purge valve is the issue, had it replaced a couple of days ago so I'm waiting to see if this will make a difference. My dealer said this is really common, one of the first things they check when people complain about bad mileage is the purge valve.

I'll post later in the week with the results, hopefully this is the problem! I've heard a good fuel line/tank cleaning could help a lot too but your car is still pretty new, I don't know if that's necessary just yet....

[Pokey]

Where is this purge valve located? Is this something the average joe can do themselves? How much was the valve?

[XTOTHEL]

How accurate is your onboard computer? Maybe try calculating it yourself.

Go to the same gas station, fill up until the pump stops.

Reset counter, drive until almost empty. Fill up again until pump stops at the same station/pump and see how much fuel that took.

[Copierguy]

my 2007 2.3 gets 500 to 600 km a tank depending on how much highway driving I do, computer says 9.2L per 100km average

[essaarcee]

my 2007 2.3 gets 500 to 600 km a tank depending on how much highway driving I do, computer says 9.2L per 100km average

what do you mean by 'a tank'? do you measure from say x kilometeres since the light comes on till the same point after you have filled up and used the gas?

[mazdabetty]

Where is this purge valve located? Is this something the average joe can do themselves? How much was the valve?

Took this from mazda3forums but it's here:

And yep you can do it yourself, gabbygenier installed mine so maybe he can offer some more info on installation, but it took maybe 10-15 mins. Dealership quotes about .5 hrs.

The valve cost me $115, that was with a discount directly from my dealer, they're normally about $130-150-ish I think.

what do you mean by 'a tank'? do you measure from say x kilometeres since the light comes on till the same point after you have filled up and used the gas?

"a tank" as in when you fill up you reset your trip odometer and let it count until you're on empty.