[StevenLK]

i have a 93 sentra 4-door E. and i took to bottom of my stock airfilter box out for a few days and i started using power premium and it seems that my car smells more , and loosing gas quick... i put the bottom back on but i do hav a AUTO and i was told to leev the OVER DRIVE off.. but would it b better on?...

 

[Zexel]

I never know about those damn Overdrive questions. My friends truck, he always fools with the OD button. I ask him almost everyday which is better. He says blah blah and I get confused and am like huh? But I think you use OD where you get to high speeds/long trips on the highway etc. Because, of course, in turn it leads to an extra gear which also shifts earlier. But to be honest with you I don't know. I would say city driving OD off. OD on on the highway/interstate etc. Why'd you start using premium? Other than performance gains if any.

 

[Scott]

The overdrive button is essentially for enabling/disabling 4th gear. That's it. It doesn't enhance performance or anything like that. If you're driving in a situation where you don't want the car shifting to 4th, turn it off.

 

[StevenLK]

I Why'd you start using premium? Other than performance gains if any.

i been using unleaded and just wanted to startt using premium.. but maybe it burns faster soo it seems like im loosing gass quickly?.. but my places go 35-45.. relly 30-40 but i like going 4-5 over the speed limit... hhaha.. but when u reach 40 and hav OVR DRIVE off.. and let goo of the gas.. it feels like it drops... like ur in TOO low of a gear.. but would u want to change gears slower? .. or faster. .. people say with it on because it sounds smoother and stuff. and changes quick but..... with it off. it doesnt need t change to high of a gear YET and it watse gas working hard to do so..??? what do you think?

 

[bahearn]

Unless the manufacturer has designed the engine to use premium fuel, or you encounter significant detonation, there is absolutely no benefit to using premium fuel...unless you work for a refinery and want a bigger year-end bonus.

Premium fuel burns "SLOWER", not "FASTER". Those are not the proper terms to use, but are close enough.

If you wrote decent English, I might be able to offer more help, but I have no idea what you're trying to convey. Something about the overdrive button...

 

[johnand]

By using premium gas in a car designed to run on 87 octane, you will just be throwing away your money, and your gas mileage will likely go DOWN. Don't use premium unless you need to. This all holds true unless you have advanced your timing, or course. To get the best economy, use the lowest octane possible that does not produce spark knock.

As far as the OD button, leave the OD on unless your transmission is hunting. That will yeild the best economy.

As far as driving habits to get the best economy:
1)Quickly accelerate to your cruising speed (Quickly doesn't mean revving the hell out of it either, just nice smooth, quick acceleration)
2)Keep constant cruising speed.

 

[razasasin]

OD on

Dude,

For fuel economy leave OD on. You only want to turn it off to
A) Keep from "lugging" in a too high of a gear while climbing a large hill, or towing
B) To save the brakes by using a lower gear to control your speed while going down a large hill.

With OD on, when you are off the gas you are in the highest gear, and basically coasting.

With OD off, the engine turns faster, and when you are off of the gas, it slows you down.

PS: premium fuel can give you slightly enhanced performance and/or slightly enhanced fuel economy.

 

[bahearn]

PS: premium fuel can give you slightly enhanced performance and/or slightly enhanced fuel economy.

ONLY if your timing is being retarded to combat detonation. Fuel economy is directly related to timing advance; more is better.

 

[johnand]

Re: OD on

PS: premium fuel can give you slightly enhanced performance and/or slightly enhanced fuel economy.

That is what the gas company's want you to think. It is false. If the car has base timing set to factory spec, the recommended octane is 87. Only if you have advanced timing, will you benefit from using premium. Otherwise you are just throwing money away.

Like I said before, the best economy can be had by using the lowest octane needed to keep spark knock away. In fact a VERY light spark knock is actually OK and provides the best fuel economy. Look in the owners manual and see that NISSAN themselves state exactly that in the manual.

For more info on how octane affects performance and economy check here: http://www.cs.uu.nl/wais/html/na-dir/autos/gasoline-faq/part3.html That FAQ tells you more than you ever wanted to know about gas.

 

[ScarCrow28]

an off topic- but related question.

what are you guys with a/t getting for mileage? i've been battling the fuel mileage problem of mine for months. i'm gettin 27-31. taht was with the low grade. now i've installed a new o2 sensor, but also advanced timing and upgraded fuel. the milage hasn't gotten better, in fact if anything it might have gotten lower. i only have done one tank of gas since so i' don't have a good average yet, but this tank seems to be yelding 27-28mpg.

is that normal for an advanced timined engine? i would think it should still be above 30, which i only get on highway, and trying real hard for mileage

 

[Oglesa]

re:
what are you guys with a/t getting for mileage? i've been battling the fuel mileage problem of mine for months. i'm gettin 27-31. taht was with the low grade. now i've installed a new o2 sensor, but also advanced timing and upgraded fuel. the milage hasn't gotten better, in fact if anything it might have gotten lower. i only have done one tank of gas since so i' don't have a good average yet, but this tank seems to be yelding 27-28mpg.

is that normal for an advanced timined engine? i would think it should still be above 30, which i only get on highway, and trying real hard for mileage
---------------------------------------------------------------------------
I have a 94 XE 2door with a/t. Bone stock. I get 31 on the highway, 24 city. Regular gas only. The o2 sensor is original as far as I know. I have never checked the timing, maybe I should! I would love to get 38 on the highway!

 

[ScarCrow28]

when you say a/t are you talking advanced timing or auto tranny?

EDIT: ok i guess you mean auto tranny. i read that advaced timing should yeild better mileage. but to me, i've gotten worse at least on this tank, haven't refilled yet.

i know part of the problem is that we don't "granny" the car around. that would yeild the maxium mileage at around 38. but i'm still expecting somewhere around 33-35. which i'm nothing near.

yes replacing the o2 sensor is one common solution. also i hear of cleaning our the throttle body, which i havn't enven inspected yet. another problem i might account to gas mileage is the fuel injectors. my #4 injector is clicking more loudly then the others. it may be clogged or whatever. but i don't have the money to replace them yet. its been clicking loudly for a few months now.

and yet another issue that i have heard, but not personally explored is dirty ignition wires. i read it on the SR20forums. the guy was getting cross fireing between cylinders. the ecu picked up on this interference, and was interpreting it as pinging. that retarted the timming. once he cleaned out his wires which apparently were quite dirty, the cross firing stopped and gas mileage jumped up. he aslo states that he gained a bit of power, due to the timming going back to normal setting.

 

[Scott]

i know part of the problem is that we don't "granny" the car around. that would yeild the maxium mileage at around 38. but i'm still expecting somewhere around 33-35. which i'm nothing near.

Unless you're doing some long distance driving 38 is pretty high. I used to average 33-35 with a manual, now that I have an auto it gets around 28-30. That's with a mixture of driving types.

 

[bahearn]

Dayum, I never got better than 30 mpg with my 5-speed SE-R. Average per tank was 26-27 mpg, with a low of 15 mpg while bombing around Texas World Speedway for two days.

 

[ScarCrow28]

well for SE-Rs, 30 seems to be pretty good. at least form what i could tell form SER.net

 

[Scott]

Dayum, I never got better than 30 mpg with my 5-speed SE-R.

I should have specified, but those are both GA16DE cars. I think the worst I ever saw was low 20's driving in the snow.

My personal record is 416 miles on a single tank, though I've heard of people doing better. I had a couple gallons left too! That was with a 91 Sentra XE 5-speed.

 

[ActivusDuThorne]

electronics

Someone posted a basic electronics for car audio site awhile back. I've had to reload my computer and lost a lots of my URL to most sites related to cars.

Does this ring a bell with anyone? If so can you send the URL to this site? I would really appreciate it. Thanks

 

[ScarCrow28]

no offense, but that has nothing at all to do with the post title of gas mileage.

you should post this in the audio or general section

 

[lakay]

A higher octane gas is designed for higher compression engine and supercharge engine. Actually, all unleaded gas is the same in all gas station so the one in Texaco or Shell is the same as in Arco, which is way a lot cheaper. Here my gas mileage with my vehicles;

'91 Sentra 1.6: 33 - 37 mpg
'97 Quest 3.0: 21 -23 mpg
'01 Frontier 3.3: 19 -21 mpg

and all these vehicle uses unleaded gas(87) from Safeway.

 

[ScarCrow28]

wow, your GA low is my GA goal. my high doesn't even go as high as your low.