cjTL

iTrader: (2)

Either replacing my O2 sensor helped my gas MPG quite a bit, or my car is pretending to be a Prius. Read on.

A check engine light came on in my car a few weeks ago, no biggie, took it to the dealer and had them replace a faulty 02 sensor. My car has 99,000 miles on it. Not thinking much of it, I went on with my business. Earlier this week I reset my trip computer just for S's and G's. Checked it today, I drove a total of 55 miles only in the city. Average speed was about 20 miles and hour, with average MPG of 19. While 19 miles to the gallon is nothing to get excited about, it is for me considering I'd always came up with an average of 17 miles to the gallon driving around town. The MPG had improved by 2. Weird...thought maybe I was just driving conservatively this week.

My point in going to check/rest the trip computer today was in preparation for making a five hour drive to Michigan. I make this drive at least once a month, and consistently average 29-30 miles to the gallon. I've never witnessed an MPG number higher than that. Well wouldn't you know it, I averaged 32MPG today. That's taking into account that fact that I was going about 81 MPH a majority of the time I was on the highway (the MPG "sweetspot" for the TL is about 65, IIRC), and the city driving leaving my house, exiting the highway, etc. I was in about a half hour of stop and go traffic too and the 32MPG number for the trip wasn't affected.

Here's a pic for reference.



I went from 29MPG to 32. And that number on the highway probably would be even higher if A) I started the trip computer while I was on the highway only. B) I obeyed the speed limit. It also might be worth mentioning that my car has never been seafoamed, though, I plan to do that when it's warmer out. So my point is, and this may have and probably has been discussed before, but an aging O2 censor seems to have quite an effect on fuel economy. I've noticed many members complain about gas mileage, etc. So just another thing to think about.

Anyone with knowledge on this matter, chime in. I'm fairly limited in my knowledge...

05TLdcc

For some reason i dont think the O2 sensor would make much of a difference, especially that much. I think you just got good gas and had cooler air for the TL to nom on so it preformed better

AGAIN, i could be very wrong.

Marmbo

The O2 Sensor can definately make a difference in your MPG. It is looking at the O2 Levels coming out of the engine and if it is reading it wrong it can add more fuel to the mixture to get the air/fuel mixture to where it thinks it should be. I don't know if it can make the up to 15% difference that I've seen claimed on some sites before but 5-10% sure.

For the past week I've been looking into my Accords fuel usage and it has gone up in the past few years slowly, most suspect thing I found is the O2 Sensor and then today I see this thread. :D

Turbonut

iTrader: (1)

Certainly depends on the location of the O2 sensor. A downstream O2 sensor won't make a difference as it monitors cat efficiency, but the upstream senor has the duty to send the correct voltage for the fuel mixture read. If the sensor is bad, the result is an incorrect mixture.

I hate cars

An 02 can definitely make that kind of difference. If it's off by 10%, that's a lot of extra fuel you're going to be dumping for no reason. I was just thinking of replacing mine even though I've never gotten a code. They can get lazy over time and mine has 99K also. Catalytic convertor life should also be extended.

DMZ

Maybe this is why my average MPG has dropped 10-15% lately. Still getting 29-30 straight highway though. 105K miles and the timing belt / water pump job was done a couple of thousand ago. Since then, the car has had more power than ever, and no, I'm not stepping on it because of that.

I'd replace my O2 sensors if I knew for sure they were the cause. Is there a mileage interval for changing them or are we supposed to wait for a Check Engine light?
.
.

Bearcat94

No interval in the Maint section of the OM as far as I can recall.



And I also believe that you could gain a couple mpg's from the replacement.

nfnsquared

I've been wondering about this myself. I'm still getting above EPA estimates on mileage and have never thrown a CEL, but I wonder how much better it would get with new upstream sensors (109K)? However, I'm not ready to fork over $250 for OEM sensors. I'm not up to speed on generic, non-OEM sensors, but they're a bit cheaper....(looks like the Bosch are $98 each)

If either of you decide to be the guinea pig, I'd be very interested in your results!

Marmbo

I'd go OEM or Bosch myself. Bosch is the company that invented O2 Sensors, I really don't see them a falling behind the competition when it comes to O2 Sensor performance/reliability.

I'm sure other companies make O2 Sensors that work just fine as well. I wonder who makes the OEM ones.

http://www.boschautoparts.com/Vehicl...artFinder.aspx

lusid

http://www.boschautoparts.com/Vehicl...=OxygenSensors

Says replace interval @ 100,000miles. Good to know

quanaman

iTrader: (4)

It is not a prius! take that back!!!


haha.

leedogg

Cool. Found all 4 sensors for just under $300 shipped. I might just do this as preemptive maintenance as I'm at 114k already.

I hate cars

I wouldn't waste your money on the two secondary sensors. These only check for catalyst efficiency but are not used for AF calculations. Or in other words, they don't affect how the engine runs. With the secondary sensors, it's perfectly fine to wait until failure to replace them.

leedogg

Thanks IHC, thats exactly what I wanted to hear/was wondering about. Down to $174 now. By secondary, you mean both downstream sensors right? Just want to be clear.

Bearcat94

Great info.

Thanks.

nfnsquared

Yep, already covered in post #4:

Now, we're all waiting for you to be the guinea pig. Get on it!

pohljm

lee, whats your mpg currently?

leedogg

It still seems to be quite fine. Averaging 25-27 mpg combined.

guitarplayer16

iTrader: (8)

Same problem; got the CEL also a while ago and replaced the O2 sensor.

Don't know if my L/100KM decreased, but it would be cool haha.

I hate cars

Yep, the downstream sensors.

You're welcome.

Sir Drake

Good thread...

I only have 46k miles, but I have thought that I should be getting more mpgs than what i get now...I average 23 mpg...
I live right off the interstate, its 12.65 miles from my house to work and 10.5 of those miles is straight interstate (70-76mph)....So multiply that by 2 which is 25.3 for round trip. I do drive in the city sometimes when I already in town, but my point is...shouldnt i be getting more than 23mph for a tank considering i drive interstate mainly?

Also, when i manually take the miles and divide by the amount of gallons its usually 22mpg or less. I reset my trip every fill up to avoid any distorted numbers.

I dont hot rod nor drive like a grandma, but do use 93 octane gas(like it asks), and even have used some gas treatment and fuel injector system cleaner, i guess to make me think its working better lol....the only time i ever get high 20s mpg, is right when i fill up and rest my trip and jump on I-24...but when i get into town it just goes down to 24mpg and slowly to 23 -22...any input guys?

nfnsquared

^^^^I meant that for leedogg (aka "O2 sensor guinea pig").

justnspace

iTrader: (1)

Normal.

in town I get 19-21mpg.

cjTL

iTrader: (2)

Glad this thread is bringing up some interesting discussion. However, I suppose I should put a disclaimer in: Do not get upset if you replace the O2 sensor and your gas mileage doesn't improve. Simply view it as another maintainence item...it'll go bad at some point anyway.

That said, I've still been holding steady at about 2MPG better than before. Perfect timing given the gas prices.

I hate cars

I agree. Your old sensors could be functioning perfect and you may see no mpg increase but at 100,000 miles it's still a maintenance item so it's not a total loss.

I can only speak in generalities here. 02s do get lazy over time. Their accuracy can go away. Since they react with fuel in the exhaust to make voltage, a "lazy" sensor will usually show a slightly leaner condition (lower voltage) and make the ECU add a little more fuel which is why they will usually hurt your mpg when going bad. A look at the fuel trims will show what's going on.

I've tried different brands with of sensors on the other car and watched the fuel trims move around. This tells me that different brands have slight variations in the calibration. I had extremely good luck with the Denso sensors in the GN. Granted this was just an old $20 one wire sensor but they made some very good 02s. I've seen far less variation in the widebands but there are still variations there. It might be a good idea to go on some of the racing sites, especially turbobuick.com and some of the LS1 sites and see what brand of wideband those guys are using and why. It could give some valuable insight as to what might be better in the TL.

triax37

iTrader: (1)

I looked around the 2G forum and it looks like people have NOT had good experiences with Bosch, so they chose Denso (or OEM):

https://acurazine.com/forums/2g-tl-1999-2003-98/p0400-egr-problem-809601/ - see post #6
https://acurazine.com/forums/2g-tl-problems-fixes-117/p0131-cel-oil-o2-connection-787433/ - see post #5

Three cheers for Search!

Ken1997TL

Your gas mileage is what my '05 TL auto got

Aman

o2 sensors, huh?

<--Is getting 17 MPG in a 4-cylinder Accord

I hate cars

That's good to know and it reflects my experiences with Denso vs Bosch and some others too.

leedogg

Glad I havent purchased them yet. I'm thinking I'll wait until there is something screwy with my mileage.