berniek

Hi. I don't use the forum very often, but it is of immense value when needed. I don't quite understand the restriction on starting a new thread to users who have 15 posts. If I have a question for which answers cannot be found, am I restricted from asking that question?

Thanks. Looking forward to your reply.

BernieK

PS: Could you please PM me at berniek@technicaldevelop.com?

TunerMaxima3000

iTrader: (4)

Right on the money, right off the hop, except I do agree with others that O2 sensors can read faulty and still be within confines of 'regular range' for ECM. This means they could be an issue, and could cause poor fuel mileage, but not THAT poor, if they're still working within ECM confines without throwing a code, then they won't kill your mileage THAT bad.

And lower the bloody pressure in your tires man that's NOT helping.

I don't know why everyone is sayin 93 Octane, the car is supposed to have 89, extra octane is a waste of your money.
And Dustey is correct in what I think he's implying, NON-ethanol fuel is better, it is getting hard to find though. Shell has ethanol free here in Canada with it's Ultra94 Product.


Then there's this useless 'XXX' per tank that's getting thrown around. That tells us NOTHING, as Dustey mentioned.
And even MPG ratings are never perfect, because some don't do it properly, and some rely on the Digital dash readout, which is NOT accurate.

And, everyone on this forum likes to forget there are 2 engines and 3 trannies that are in our cars, if you're not specifying what you have your posts are furthermore useless. I ASSUME that the OP has a 02/03 and it's automatic. I had to figure that out myself from your 'grandma' comment, and the comment I quoted above telling me you have a digital readout.

P.S. The 02/03 with Auto is the worst of all our Maximas on fuel straight out of the factory:

00-01 5spd = 22/28 MPG
00-01 Auto = 20/28 MPG
02-03 6spd = 21/28 MPG
02-03 Auto = 20/26 MPG
------------------------------------------------------------------------

If you want to have an intellegent fuel mileage thread, you need to use accurate numbers comparing apples to apples, and that is hard to do, everyone drives different, and everyone has a different opinion on city/highway, and 'hard' driving. At the end of the day, it's all subjective.

I hope you get good results with changing the main 02's.

tcb_02_max

iTrader: (5)

Yeah, above a certain pressure (let's say about 34-35 psi), increasing your tire pressure to lower rolling resistance has very diminished returns. Plus, your tires will wear unevenly.

Agreed, although I was under the impression it stated "Use premium for best performance," which would be 91 (R+M)/2.
Preach it, brother! I've been annoyed by this stupidity for quite some time.
+1

TunerMaxima3000

iTrader: (4)

It states that on the gas cap. If you Read your owners manual or look in the FSM, recommended octane is 89, does it hurt to run 93/94? No, but if you're just putting around town, you're wasting your money putting anything more than 89 in.

Personally, I have not found a fuel mileage difference between 87 and 89 on my car (2001 Automatic) so I just run 87. I think the DE-K and 3.5 are more tolerant to lower octane than the old VQ30DE was.
And regular gas is over $1.20/liter here ($4.52/Gallon if I did my math right)

J-Rod

iTrader: (1)

essplain wasting money? if 89 octane (plus at most stations) is $3.00... and prem. (91-93 at most stations) is $3.09 and I generally avg fill up 15 gallons... that is a whole $1.35 difference in price of 89 octane and in my case 93 octane. I usually fill up twice a month that's an extra $2.70/month... and that is $32.40/year... yeah i can get by not eatting that McDookie double cheese twice a month and put a better product in my car. That wasting money BS is so "ZOMG your doing it wrong.." hype pure and simple. And for 11yrs of ownership, on my 2000 max, that is a total of $356.40 extra. and i'm being way over because the price difference in regular unleaded and prem was only $.10 in difference prior to the 2008 oil bubble in the stock market, only then did it go to the $.20-.25 in difference we see now. so that number is really closer to $225-250 over the years. How much were those 4 O2's again? Mine test fine with about 128,XXX miles on the clock.

Prem goes in my lawnmower, weedeater, leaf blower, power washer, 3 vehicles, boat and the jet ski. for a few lousy bucks...

now a import beer over a domestic... in price, thinking that import is sooo much better = that's wasting money.

EDIT: ohh and if i don't run 91 or better it pings like crazy in this Texas heat, don't tell me that pre-ignition, timing retard, and uneven fuel burn off is any better than savinng that $1.35/tank

J-Rod

iTrader: (1)

sorry and to OP, (1) I would remove and test the front two "main" O2 and see if they are working or "lazy" and go from there. another consideration is your MAF, mine was bad and wasn't throwing codes, and when i changed it noticed a little better fuel mileage. (2) if there is a code for your cam sensor then something is wrong, no way around that... you can reset it but it throwing a code means something is wrong. get it checked (3) and running 38 PSI in your tires is perfectly fine too. even if you don't have lo-pros and still have stockers. Just don't exceed the recommended tire max when cold, which you can run them up to that psi if you like as well.


Edit: my bad, noticed you said E93 and if it is an ethanol blend... then it is known that you get less mileage than "normal" gas. It's less efficient, more expensive to manafacture, and pollute's more... but the government sez its the fix so it has to be good, right??? :rolleyes

TunerMaxima3000

iTrader: (4)

The difference between Regular (87) and Premium (92-94) is usually around $0.10 per liter in Canada.

Full tank (around 70 liters)
$84 @ 1.20
$91 @ 1.30

The price for Ultra94 is a few cents higher again.

You also calculated based on $.10 difference per gallon, when your actual difference is $.30

Your numbers should actually reflect mine, the difference in cost for a full tank will be close to the numbers I presented.
Is it a lot? No. That's $6 difference every fill up. My point is, why the hell would you spend more on gas then you have to? It's already expensive enough, every dollar counts.

You make a very valid point though.

ColdRain

I completely agree here. cost is actually $.30 when going from 87 to 90+, so complete fill up gets to $5 in difference. On top of that, my 2001 doesnt ping either if I put 87 and mileage is no difference at all.

Eirik

iTrader: (2)

TM3K: I actually added a new formula to my fuel economy spreadsheet just to answer that question: How much more money have I spent on 93 octane fuel instead of 89?

The up-charge from regular to premium around here is either $0.18 or $0.24, depending on the station. Using a $0.22 premium, I mostly fill up at the $.24 up-charge Shell than the $.18 up-charge Thorntons, I have spent $83.02 since June of 2010, over 7371 miles driven and 378 gallons. My average price per gallon, for premium fuel, over that same time is $3.03. 'Course, it recently shot up $0.50 a gallon, and I expect to pay closer to $4 a gallon over the summer, but .

Based on the miles I drive, I spend an extra $117 a year on premium fuel. Why put up with downgraded power when the ECU detects the less knock-resistant fuel? In the American south, where our blood runs crude, it simply doesn't add up.

J-Rod

iTrader: (1)

@tuner & @coldrain

maybe you both read my post incorrectly as I was comparing a mid-grade (I said "plus" as that is what it is called) to the prem. I didn't even mention the regular (lowest - 87 octane) gas...

So my numbers are correct.

ColdRain -- you shouldn't compare reg. unleaded to the prem. unless you are putting whats not recommended in to be begin with. I made the comparison of price difference it what the least suggested octane is by manafacture (89 octane) and the prem. for what is suggested. That is a $ comparison. $.30 difference isn't anywhere close to the norm around me (Houston) from regular to prem. - I see about a $.18 - $.22 difference in those prices. And really about $.04 - $.08 difference between the plus and prem., so actually i cheated myself a cent in my comparison.

It's not a waste of money, unless your hurting so bad for that 5 bucks at the end of the month... in which case gas prices are the least of your concern's.

Eirik

iTrader: (2)

Yeah, I just take the premium fuel as an added cost of ownership.

naijaboy

Err, I know this thread is old but I'm wondering how come none of the posters who planned on replacing o2 sensors came back to the thread to post the outcomes if any?

clintb3astwood

iTrader: (10)

Don't go crazy and change all of the o2 sensors, the primary ones bank 1 sensor 1 and bank 2 sensor 1 are the ones that matter most in terms of mpg, the other two can actually be simulated and never used again. My car was dumping gas last week like crazy, 13.8 mpg. Scanned the car and i had a cam position sensor code, swapped it out and got back 33.5mpg on the highway, not accurately obviously but yea check those, and exhaust leaks too.

naijaboy

Hmm...thanks for the feedback

Amave

yeah that annoys me as well.

IF you want to replace your oxygen sensors, replace the ones on the primary exhaust manifold. There is one closest to the firewall on the manifold and the other one by the radiator , even if you dont have a CEL , its a good idea as a maintenance item . If you wan to test them you have to get the wiring diagram and locate the signal wire and tap into the voltages and rev your engine while checking the volts.


If your voltage hovers around .5 volt then your sensor is good.

If you remove the brake booster hose and the volts drop to .1 volts then that means its working ok , because when you add more air, the sensor reads the extra air and it adds fuel accordingly to richen it up.



here take a look

http://www.youtube.com/watch?v=stFhLSHsOGg

dhundley79

new guy <~

00 Max GLE Auto 175k

bought it 2 weeks ago so Cant give MPG. im at about 180 with close to 1/2 tank.
On the way to have it inspected by a local dealer (friend is the mechanic) my cel came on. Had it scanned at advance auto (did not get the code). said bank 1 sensor 2 shows code. buddy said there is a TSB for the o2 sensors and that I should replace both downstream sensors and have the ECU reflashed. its EXPENSIVE, said they have had bad luck with aftermarket sensors. well my question is how is it that people are replacing them and not having issues? what do you guys think? also im mechanically dumb. how do you know if you have a California ESV vehicle?