23 mpg...really???

[Yury]

Everyone here seems to talk about how great a mileage they get, but how about this: my last tank was 23 mpg. What the...?

A tank just before was 29.5. Not stellar either, but 23 is ridiculous.
It's a 08 auto with low mileage and no problems whatsoever. TB cleaned a couple of weeks ago, MAF is clean, tires are properly inflated, injectors cleaned off car just this winter. Driving style: grandpa.

99% city, often with wife and two small kids and AC on 100% because it's been very hot and humid. I understand it's going to affect the mileage, but 23...how are you guys getting high 30s in all city driving? My personal best is 34 when I was driving mostly highway.

I am tempted to get the at fluid changed even though it's far from due. Other than that I just don't know anymore..

[edmscan]

Where in Canada do you live ? Calgary ... the drivers there are terrible. But I would tend to agree .. that does sound like something is not quite right. Are you sure you are calculating it right ? How many KM are you getting in a tankful ?

[fnkngrv]

I would usually lose about 3mpg with the AC cranked 100% and using it constantly as a point of reference. I am not saying that the 23/24mpg is acceptable for city, just giving you a point of reference. Perhaps an ECU reset by disco the battery for 30 minutes or so to make it relearn your long term fuel trim may help? Other than that have a scangauge connected to see what is happening during load.

[WeeYari]

It can happen. I've gotten very close to that low myself.

Since you haven't stated where in Canada you are I'm going to assume your weather conditions are what I've been experiencing this past month. Constant >30c heat.

At these temps, the air is very thin and combustion can be air starved resulting in less efficiency. Combine that with 100% A/C, 99% city, and often a full passenger load and you will suffer. This engine hates A/C (and weight).

Most of the people touting high mpgs are not running constant A/C, and are almost always the single occupant of the vehicle.

My last fillup, yesterday, saw 27.85 mpg. That was mostly city, with very little use of the A/C.

Edit: Just check another thread. You are in the GTA and living the same conditions as me.

[caineroad]

OP please tell us how many KM you get for a full tank.

I dont know my mileage but I get about 430-460km (depends how hard i drive) then the last bar flashes.

Also the stupid ethanol contributes to our fuel mileage too,

[Yury]

Originally Posted by edmscan

Where in Canada do you live ? Calgary ... the drivers there are terrible. But I would tend to agree .. that does sound like something is not quite right. Are you sure you are calculating it right ? How many KM are you getting in a tankful ?

Toronto. I reset the trip A on fill up and on the next fill up divide the liters I put in by the amount of km on the trip A.

This time around I went to 2 bars and if I remember correctly the trip was 270 or so...the number of liters that I put in was about the same as km traveled. Normally I go by half-tanks and on bad fillups like this it is around 210 km. On better fillups I get maybe 250.

The drivers here are pretty average. I almost never have to brake hard.

[Yury]

Originally Posted by fnkngrv

I would usually lose about 3mpg with the AC cranked 100% and using it constantly as a point of reference. I am not saying that the 23/24mpg is acceptable for city, just giving you a point of reference. Perhaps an ECU reset by disco the battery for 30 minutes or so to make it relearn your long term fuel trim may help? Other than that have a scangauge connected to see what is happening during load.

the fuel trims are about usual. small single digits under load and about -4 idling. I have seen these numbers in winter too. In my experience if I disconnect the battery long term trims are zeroed but go back within like an hour of driving. I can try, but I don't have much hope.

Btw, no need to keep it disconnected for 30 min. I tried disconnecting for a few minutes and it got the long term trims zeroed just fine.

[Yury]

Originally Posted by WeeYari

It can happen. I've gotten very close to that low myself.

Since you haven't stated where in Canada you are I'm going to assume your weather conditions are what I've been experiencing this past month. Constant >30c heat.

At these temps, the air is very thin and combustion can be air starved resulting in less efficiency. Combine that with 100% A/C, 99% city, and often a full passenger load and you will suffer. This engine hates A/C (and weight).

Most of the people touting high mpgs are not running constant A/C, and are almost always the single occupant of the vehicle.

My last fillup, yesterday, saw 27.85 mpg. That was mostly city, with very little use of the A/C.

Edit: Just check another thread. You are in the GTA and living the same conditions as me.

What I don't get is how different fillups can be with no significant changes in weather. It's been hot summer so far and I get deviations of 5 mpg between subsequent fillups.

EDIT: which tread are you referring to?

[WeeYari]

Originally Posted by Yury

EDIT: which tread are you referring to?

The List of GTA Members thread in which you indicated Thornhill.

[vten]

Bad O2 sensor perhaps ?

I have 08 Yaris HB , 30xxx mi on the odo, supercharged with aftermarket adds on. 17" wheels and Use a/c all the time and still getting 33-36 mpg..... That's with an O2 sensor CEL code tho ... (ordered the new part n waiting to arrive)

[fnkngrv]

going on half tanks or other partials can be very subjective. with how much the fuel moves around in the tank I have personally experienced divations anywhere from 5-20 miles on the OD and have tested by actually refilling after 2,3, & 4 bars down. Add in the heat/humidy indices and it can really wreak havoc on FE. I had a couple tanks while in Memphis in 08 and then again in central AL last summer that were very similar to your experience during the dog days of summer. I also had a few tanks the last couple winters where I avg around 22/23 as well. It sucks, but it can happen.

[Yury]

Originally Posted by WeeYari

The List of GTA Members thread in which you indicated Thornhill.

Oh that. I misunderstood you. Yes, I am at the very south part of Thornhill.

[Yury]

Originally Posted by fnkngrv

going on half tanks or other partials can be very subjective. with how much the fuel moves around in the tank I have personally experienced divations anywhere from 5-20 miles on the OD and have tested by actually refilling after 2,3, & 4 bars down. Add in the heat/humidy indices and it can really wreak havoc on FE. I had a couple tanks while in Memphis in 08 and then again in central AL last summer that were very similar to your experience during the dog days of summer. I also had a few tanks the last couple winters where I avg around 22/23 as well. It sucks, but it can happen.

I am only using bars as a rough indication and do the math after each fill up.

[WeeYari]

Originally Posted by Yury

Oh that. I misunderstood you. Yes, I am at the very south part of Thornhill.

Yeah, I meant to say 'checked'.

[Yury]

Originally Posted by vten

Bad O2 sensor perhaps ?

I have 08 Yaris HB , 30xxx mi on the odo, supercharged with aftermarket adds on. 17" wheels and Use a/c all the time and still getting 33-36 mpg..... That's with an O2 sensor CEL code tho ... (ordered the new part n waiting to arrive)

If the lambda sensor was off I imagine I'd see funny long term fuel trim numbers due to discrepancy between lambda and MAF sensors.

[WeeYari]

At this point I'd say just sit and monitor for a while. Do more frequent smaller fillups so that you can do the math against a narrow list of environmental and physical variables.

[tooter]

Originally Posted by Yury

Everyone here seems to talk about how great a mileage they get, but how about this: my last tank was 23 mpg. What the...?

A tank just before was 29.5. Not stellar either, but 23 is ridiculous.
It's a 08 auto with low mileage and no problems whatsoever. TB cleaned a couple of weeks ago, MAF is clean, tires are properly inflated, injectors cleaned off car just this winter. Driving style: grandpa.

99% city, often with wife and two small kids and AC on 100% because it's been very hot and humid. I understand it's going to affect the mileage, but 23...how are you guys getting high 30s in all city driving? My personal best is 34 when I was driving mostly highway.

I am tempted to get the at fluid changed even though it's far from due. Other than that I just don't know anymore..

Have you tried installing a new air filter?

Really humid air could be moisturizing the dirt on the filter and make it "pack" into the filter fibers and clog the filter reducing air flow and decreasing gas mileage. I've seen that happen on the return air filters of home central heat/cool systems.

[Yury]

^ the filter is only a couple months old.

Besides, I've been led to believe that in FE vehicles a dirty filter degrades power, not mileage. Fuel injection will compensate the injector pulse to keep the mixture stoich, i.e. with less air it'd inject less fuel. So, I'd imagine the net result would be the same as less throttle.