# Average Mpg's with an Auto Trans



## schoust (May 27, 2008)

Hey Guy's I was wondering what everyone was getting for milage on the car? I am averaging about 30mpg and I'm not sure this is optimal??


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## nissannick1 (Feb 22, 2008)

I get between 20 and 25 depending on how I drive it. I wish I could get 30mpgs.


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## schoust (May 27, 2008)

Ok Guy's I need more data here I really want to get better mpg with this car otherwise it's simply not worth it to me to drive a small car like this. I have been averaging around 26-27 mpg. I warm the car up every mourning for about five to eight minutes and I have a trunk full of tools of the trade about 75lbs. What are you guy's with the auto's getting? Oh I'm running regular unleaded and the car has had a fresh tune up and the timing was also checked so it's running decent. I always thought that I would see at least 30 or better???


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## GA16DE (Jun 23, 2005)

I get 33-34 on the highway at ~65mph, but in town I usually get 28, maybe 29.


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## ixoyerpo (Dec 10, 2008)

i drive highway mostly to work 35m about 80m roun trip i get about 385-400 depending on the speed.


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## schoust (May 27, 2008)

Hmm I seem to be stuck at around 27 mpg not very impressive at all? I believe that I am running rich and therefore burning excess fuel. But the thing that puzzles me is the fact that I have not seen any cell since my engine tranny swap? It's almost as if that feature is not operable anymore for some unknown reason? I still am not totally happy with the 96 hp rating.


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## IanH (Feb 11, 2003)

Try changing the front O2 sensor, it controls the mixture and wont throw a code.
My Subaru dropped MPG with age, and when i put in a new O2 sensor i picked up 2 mpg in the city and highway. this was over a few thousand miles. it didn't return mpg highway to new, however in city was close!!!
I haven't replaced either of the B14's O2 sensor !!
BTW both the B14's have manual's so i cant comment on your Auto mileage.


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## xcountryflyer (Dec 25, 2007)

Is that highway, city, combined? You could always look for low rolling resistance tires next time, but the downside is that they are less sticky in handling and braking, but then the Sentra sedan isn't the most sporty car anyways....


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## GA16DE (Jun 23, 2005)

Also the way you accelerate, how early and how hard you hit the brakes, how much over the speed limit you go, etc., can influence gas mileage.


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## xumox (Jan 18, 2008)

i think my B14 has a problem, i'm getting 19 mpg in the city, my engine is a GA16, my B14 is on 18" wheels and the suspension is really hard and i have 2 Audiobahn 12" subs in the trunk, what do you people think about my milleage.


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## schoust (May 27, 2008)

Well I checked it again and combined city and highway is right around 27 mpg. I really thought I was going to be at 30 or so and to be honest the number is a bit disapointing considering the enemic performance. I will also add that there is a slight misalingment issue that I need to correct and I still believe that there has to be something else that I am missing as far as the performance of the engine. I still have a bit of a hesitation and a flat spot here and there that I can not figure out? I almost want to have the injectors gone through to make sure that they are not the problem? This engine sat on a shelf for several years making me think that maybe the injector spray pattern could have been effected?


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## GA16DE (Jun 23, 2005)

18 inch wheels can hinder performance by adding very unnecessary unsprung weight, but I don't think it should change it by ~8-9 mpg. Have you checked things like plugs, wires, distributor cap, etc.?


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## IanH (Feb 11, 2003)

My gxe EPA mileage on the sticker new was 29 city and 38 hwy.
I got 25 around town, ie 22 - 26 in Dallas traffic.
On the highway it did 35 -36 when new and stock.
With 15 inch wheels, bigger brakes, it did 30 to 32 on a 200 mile each way trip Dallas to Austin to Dallas at 70 - 80 mph
I don't believe the Auto will get close to this regardless of EPA mileage because its an older design 4 speed.
If you remember they lowered the EPA mileage by 10 - 15 % because of complaints it didn't reflect what was obtainable.

If you really are getting 27 combined I would say that's good and similar to my 25 - 26 around Dallas.


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## xumox (Jan 18, 2008)

i will check them and also i'm thinking on changing Oxygen Sensor, i think that with the mods i've made i should get about 25 mpg, but not 19 (city of course)


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## IanH (Feb 11, 2003)

Is the B14 Auto 3 or 4 speeds ?


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## xumox (Jan 18, 2008)

mine is 4 speed auto, and something important is that i haven't made mods to gain power, i just installed 18" wheels, a set of lowering springs and a couple of 12" subs, this stuff makes my car loose mpg but not too much likes the mpg i'm getting.


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## IanH (Feb 11, 2003)

I agree, also check your coolant temp sensor, that's been reported to go bad and give bad fuel mileage.
Dont know if Air temp sensor will give a problem, but worth checking.
Would be nice to know what you get on the highway on a longer trip.


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## voulo5 (Jul 13, 2008)

personally ive traveled 600-700 miles on 1 tank of gas doing 65+ MPH so idk how good that is but ill assume its good lol



IanH said:


> I agree, also check your coolant temp sensor, that's been reported to go bad and give bad fuel mileage.
> Dont know if Air temp sensor will give a problem, but worth checking.
> Would be nice to know what you get on the highway on a longer trip.


and quick question, how do i check the coolant and air temp sensors, my MPG seems to be getting worse over time :|


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## IanH (Feb 11, 2003)

well if you are getting 500 - 600 miles per tank at 65 mph then obviously nothing is wrong !!
when you were getting this mileage on a trip what was your in town mileage ?
Download the FSM and it will tell you how to check the sensors. I haven't done that so i would have to look it up.
I would check the coolant temp sensor first, Air temp sensor and then replace the O2 sensor unless the O2 sensor has done over 100K then i think it needs to be replaced anyway.


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## sentra77 (Aug 3, 2008)

i get between 19-25 my foot is always to the floor tho


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## xumox (Jan 18, 2008)

IanH said:


> I agree, also check your coolant temp sensor, that's been reported to go bad and give bad fuel mileage.
> Dont know if Air temp sensor will give a problem, but worth checking.
> Would be nice to know what you get on the highway on a longer trip.


what about the check light, if one of those sensor is bad it should turns on or i'm wrong


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## IanH (Feb 11, 2003)

How does it know the engine is at 77C and the sensor reads 30C
So the ECU thinks your engine is cold and give more gas ?
If the sensor goes open then yes you would expect a check engine light.


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## xumox (Jan 18, 2008)

IanH said:


> How does it know the engine is at 77C and the sensor reads 30C
> So the ECU thinks your engine is cold and give more gas ?
> If the sensor goes open then yes you would expect a check engine light.


Can i verify myself that my sensor isn't working perfectly? how?


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## IanH (Feb 11, 2003)

xumox said:


> Can i verify myself that my sensor isn't working perfectly? how?


this is from the FSM. If you havnt downloaded one I suggest you do, they are very usefull ( and Free)


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## IanH (Feb 11, 2003)

you can measure this on the car, i suggest when its been off for several hours and at ambient temperate.
Measure the temperature and then the resistance of the sensors with a digital Ohm meter.


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## xumox (Jan 18, 2008)

IanH said:


> this is from the FSM. If you havnt downloaded one I suggest you do, they are very usefull ( and Free)


where can i download it?


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## IanH (Feb 11, 2003)

you can try phatg20.net if it is up now, its been reliable for years but went down a few weeks ago
or I have a 97 which is as close as i can get you 


unfortunately Mickeysoft want you to register, use your hotmail account if you have one, other wise you have to register.

If you cant unpack the .rar file peazip is free and does the job


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## IanH (Feb 11, 2003)

well i just checked and Phatg20 is still down....


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## IanH (Feb 11, 2003)

sorry wrong link try this one

1997_Sentra.rar - Windows Live


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## lionshooter (Jan 1, 2009)

My 96 GXE, 225,000 miles, manual, stock tires and wheels at 35PSI. Runs 80 miles daily on the Xway and consistently gets 34MPG


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## Mr200 (Oct 21, 2007)

95 200SX SE 1.6 Auto 34MPG consistently.


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## schoust (May 27, 2008)

Hmm 34 mpg with an auto? Wow how are you acomplishing that feat?


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## Mr200 (Oct 21, 2007)

schoust said:


> Hmm 34 mpg with an auto? Wow how are you acomplishing that feat?


Just drive conservatively. Actually I don't drive it much, my 17 YO son does. I however end up paying for fuel and performing maintenance on it. Keeping it in good tune helps. Proper wheel alignment as well. Another important item is tire pressure!!!!!

Injectors cleaned within the past 2 years.

Some months back I lapped the valves, honed the cylinders and replaced the rings too. All in all I found the 1.6 to be a pretty well designed engine.

John


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## GA16DE (Jun 23, 2005)

Not hard to get 34 mpg. I got about 33.7 mpg here while back just driving ~65 mph on the highway (my speedometer is off by 2-3 mph, so I'm not sure exactly how fast it is). Between that and being easy on the throttle, it's pretty easy.


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## MadRacerX (Jan 14, 2009)

Here is another factor that gets overlooked, the transmission condition. If the tranny is slipping, or on its last leg and about to go, lots of power can be absorbed by it and cause dismal gas mileage. And, making your cars intake and exaust more efficient(without adding too large of a pipe on the exhaust end to lose low end torque) can actually help gas mileage. Alignment and air pressure are also critical. I have my tires up around 40, yet know that at 50 i could get even better(at the expense of comfort and handling/braking). Also, if your rotors are warped or calipers sticking or the rear drums overadjusted, this all affects how well the car can roll freely down the road. Oh, i get usually 29 mpg nearly everywhere i drive unless i race more than 40 percent of the time, and then it only drops one or two mpg. On a highway trip over the summer i got 37 mpg. This was all with 17 inch rims/tires. I have my stock 14 inch rims on now, and like the accelearation "mod" and better braking with nearly the same handling, so might not go back to the 17's now that i have lowered the car. And yes, lowering the car, if done right and if it is properly aligned, allows less air, and thus air resistance, under the car, and yeilds higher gas mileage. And yes, forgot to mention, a very crisp shifting auto transmission with a little over 100k on it. Planning on taking the risk and mixing 4 quarts of synthetic tranny fluid to see if that won't hurt and also maybe help gas mileage. I also sometimes mix 1 to 3 oz of xylene/acetone mix, and i do get more power, but not much more mileage(probably as i drive harder), however i feel this mixed with cheap 87 octane gas, at least acts like a super cheap fuel system cleaner, and allows for max mileage from the ECU. One last thing, don't advance your ignition timing. I luckily memorized where it was when it was stock after getting worse mileage and not any added power from advancing my timing. I now have a scanguage II, and notice the ECU will automatically advance or retard the timing as it sees fit, regardless of where u thing u have "fooled" or "advanced" the timing, as knock sensors and any values it doesn't like are put back to normal nearly instantly. I know that mod needs higher octane, and tried it with 89, yet noticed the same or less power/mileage. Yet somehow, at the stock setting, i get max mileage, so i don't mess with it and work on other ways to get power.


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