240sx guzzling gas!!

[chlatboy]

Hey guys, just had a question. My friends s13 240 eats a lot of gas and we dont know why. he only gets about 70 miles with 5 gallons of gas. My s14 gives me about 20 miles a gallon so i make about 100 miles with 5 gallons but his only gets 70. Anyone know why his car would be eating so much gas and how to fix it? Any ideas would help. Thanx

[idlafie]

Could be all kinds of reasons why your friend is getting poor gas mileage. Those reasons range from driving style, (jack rabbit starts at streetlights / lead footed driving), aerodynamic drag, (driving with windows / sunroof open/closed, big ass'ed wing on the hatch, roofrack, etc), or vehicle maintenance / performance, ( improperly inflated tires , brakes dragging, driving with the A/C on, etc).

If your friend wants to see if he can improve his gas mileage, then have him do a tune up. Change out the air, oil & gas filters. Replace the PCV valve, distributor cap & rotor, spark plugs & wires. Take a bottle of fuel injector cleaner & pour it in the gas tank along with spraying the Intake Manifold & EGR valve with a can of carburator cleaner to clean out the carbon buildup inside. Also put the ECU into Diagnostic mode & test the Engine Coolant Temperature Sensor along with the Oxygen sensor. If any of those two sensor appears to be performing poorly, replace it. Also, check your idle and timing to make sure your engine is running at it's peak efficiency. Check your tire inflation & make sure the tires are properly inflated. Pull your wheels off & check to see if the wheel bearings are spinning properly & the brake pads are not dragging against the rotors.

All these little factors can add up and affect your gas mileage. Doing a tuneup doesn't hurt...it only helps your engine run better.
Anyhow...hope this helps...
ID
95 SE

[wootwoot]

poor gas mileage can be a sign of a bad o2 sensor

[sticky240]

i second the tune up

just did one and now i'm getting about 325miles per tank when before the tune up i was getting around 300 or so

[mad sentra]

third on the tune up. Just get everything cleaned up and swapped out. More than likely it's just a tiny discrepancy in the running of the motor, or his driving style. It could be he needs to run some injector cleaner, or he's just running too rich....

[aznpoopy]

Hey guys, just had a question. My friends s13 240 eats a lot of gas and we dont know why. he only gets about 70 miles with 5 gallons of gas. My s14 gives me about 20 miles a gallon so i make about 100 miles with 5 gallons but his only gets 70. Anyone know why his car would be eating so much gas and how to fix it? Any ideas would help. Thanx

u both get sucky mileage. your s14 needs a tune-up as well.

[idlafie]

u both get sucky mileage. your s14 needs a tune-up as well.

Azn,
Just out of curiosity, how many miles to the gallon do you get on your car??
Is this on a stock ECU or reprogrammed ECU? Any other mods to your car??

Reason I am asking is because according to Nissan literature I've found on the net, the stock 95 S14 is supposed to get 28 hwy/22 city on a manual transmission & 26/21 on a auto transmission. The 91 S13 is supposed to get the same as a S14 - 28 hwy/22 city.

I've been tracking my gas mileage since June of 2003 and I've been averaging 20.89 miles to the gallon plus/minus 1.72 mpg. This is a combination of street and freeway driving. I check my timing & idle practically every month & try to make sure the engine is kept in top shape at all times. Tires are inflated to 35 lbs & there is no drag in the wheel bearings / brake pads. I'm running on a stock ECU with Injen intake with CAE & an aftermarket Fujitsubu exhaust. I've also got NGK plugs & wires. Engine is lovingly maintained & serviced practically every month. O2 Sensor is operating within specs as I check it regularly with an aftermarket OBDII scanner that reads info "realtime" off the ECU.

Other than changing my driving style, (cutting back on the jack rabbit starts at the streetlights & stop speeding on the freeway), I can't think of any other way to improve my gas mileage....Driving like an old lady is NOT an option!!...My S14 is just too fun to drive....:) :)
What else can you suggest??

[Armysweitzer]

I get 30 mpg MIXED and i do drive like i have brakes, I usualy shift around 3-4. I have a pretty much stock de. Things help like removing engine fan, remove ac, remove any weight for that matter. I always use 93 octane at mobil which i think helps cause its nice clean petrol.

On a side note my car is just awesome cause even full highway runs to 120 and races here and there I still get like 22-25 mpg mixed. Maybe im just lucky.

-Johann

[sepulchral]

as for fuel injector cleaner do 2 cans of BG44K thats the only stuff that works

[ghostuss]

shoot i use that Chevron stuff from Kragon... I do realize a much better mileage with that stuff thou. Just my 2cents.

[s13driver]

a year ago b4 i had my tune up i got ~25mpg ~400 a tank. but as soon as i did the tune up it starts to drop. now i 'm only getting ~20mpg ~300 a tank :wtf: any ideas on this one ? btw everything should be in good shape as far as i can tell

[AlligatorBling]

i get 350ish to a tank... take care of your car and your car will take care of you. also... try a seafoam treatment. im all about some damn seafoam =D

[TachyonS14]

I've done a full tune up on my KA, and get around 20-22 city and around 28-30 freeway. And when doing that freeway driving, I usually have the tach between 3.5-4k.

Also, I did seafoam treatment and didn't really notice a huge difference, but I bet it cleaned the engine pretty good so it was worth the time and effort.

[chlatboy]

Ya we already did the tune up part of it. That is why im asking. We didnt check the O2 sensors yet. Mite give that a try. SO basically we would have to take it to get dianosed huh. ANd im not sure how much mileage im supose to get. I just try to get around 20 miles a gallon. all i know is that my light ever turns on so it must mean that i still have more gas.

[AKADriver]

Serious fuel overconsumption like that points to a severe rich condition. Tires, driving like an idiot... these can only take off a few points. 14mpg indicates a serious problem.

Before yanking out the O2 sensor, I'd make sure there are no vacuum leaks, and clean out the MAF and AIV.

[DJ_Sunrise]

you guys think 14mpgs is bad? hah, visit me at work in Princeton NJ when im delivering pizzas.. moderate driving, 8mpg.. top that!!! i can smell my gas out of my exhaust on occasion, but not during idle or if cars standing.. only under stress.. anyone have any ideas?

~Sunrise

[Steeles]

chit I still get 300 miles out of 12 gallons or so. and thats with 850cc injectors.. and Im running a bit rich. everywhere. and drive like my girls about to give birth. everywhere.

[aznpoopy]

Azn,
Just out of curiosity, how many miles to the gallon do you get on your car??
Is this on a stock ECU or reprogrammed ECU? Any other mods to your car??

Reason I am asking is because according to Nissan literature I've found on the net, the stock 95 S14 is supposed to get 28 hwy/22 city on a manual transmission & 26/21 on a auto transmission. The 91 S13 is supposed to get the same as a S14 - 28 hwy/22 city.

I've been tracking my gas mileage since June of 2003 and I've been averaging 20.89 miles to the gallon plus/minus 1.72 mpg. This is a combination of street and freeway driving. I check my timing & idle practically every month & try to make sure the engine is kept in top shape at all times. Tires are inflated to 35 lbs & there is no drag in the wheel bearings / brake pads. I'm running on a stock ECU with Injen intake with CAE & an aftermarket Fujitsubu exhaust. I've also got NGK plugs & wires. Engine is lovingly maintained & serviced practically every month. O2 Sensor is operating within specs as I check it regularly with an aftermarket OBDII scanner that reads info "realtime" off the ECU.

Other than changing my driving style, (cutting back on the jack rabbit starts at the streetlights & stop speeding on the freeway), I can't think of any other way to improve my gas mileage....Driving like an old lady is NOT an option!!...My S14 is just too fun to drive....:) :)
What else can you suggest??

sorry i haven't checked back to this thread in a while...

i average about 25mpg running 91 octane. with heavy freeway driving i can easily get 30mpg. i have a s14 base model, k&n filter, old ass o2 / sparkies, z32 fuel filter, etc... basically very near stock. typically in city driving i won't take it past 4.5k and try to keep it under 3k as best as i can. highway driving i seem to get better mileage the harder i push it. i get 30mpg if i keep it at 80mph or so. if you've done all the basic maintenance i don't see why your mileage sucks.

if i'm careful i can get 350 miles to the tank... if i screw around sometimes it can come in as low as 280 or so.

[idlafie]

you guys think 14mpgs is bad? hah, visit me at work in Princeton NJ when im delivering pizzas.. moderate driving, 8mpg.. top that!!! i can smell my gas out of my exhaust on occasion, but not during idle or if cars standing.. only under stress.. anyone have any ideas?

~Sunrise

Check the wire leading to your Engine Coolant Temperature Sensor. There may be a short in it causing your ECU to think your engine is still cold, (even though it may already be at normal operating temperature). Remember..your ECU dumps extra fuel into your intake manifold when the engine is cold. It does it primarily to warm both your engine & catalytic converter up as quickly as possible so your engine doesn't pollute. Once your car reaches normal operating temperatures, the ECU is supposed to cut back on fuel delivery, but if the ECU is not reading a signal from the Engine Coolant Temperature sensor, or reading the wrong signal, then the ECU will continue to dump more fuel into your intake...causing you to run rich & get crappy gas mileage.

To see if your wire/connector is shorted out, try wiggling the wire where it connects to your Engine Coolant Temperature Sensor. If your idle starts to flucuate while you are wiggling the wires, then you definitely have a short in the connector wire. Only way to fix it is to cut the wire leading to the sensor, take the connector apart, re-solder the wire back to the replacement spade inside the connector, put the connector back together then reconnect the connector to the Engine Coolant Temperature Sensor.

I've seen this happen alot on a bunch of S13's I've worked on...especially the older 89-90's....

Anyhow, hope this helps...
ID

[DJ_Sunrise]

i never thought of that.. good idea, i hope it helps.. :naughtyd: if this works..why.. youll save me hundreds of dollars a month.. *sniff* :w00t:

~DJ Sunrise

[chlatboy]

okay i checked the o2 sensor and its cut where the wire connects with the others. Its cut right before it is bundled up. Now i see that there are two coatings of wires. The silver wire on the outside and a gold wire on the inside. HOw am i suppose to change the wire and can i just have the wires touch or would i have to have silver link with silver and gold with gold?

[idlafie]

From what I've read and can recall, the wire leading to the Oxygen sensor is a shielded wire....gold wire surrounded by a metal braided wire. Fixing that connector is gonna be a bitch...for two reasons.
1). You may have to find a replacement wire...which may or may not be easy. Check your automotive supply stores...they MIGHT carry it..OR
hit a junkyard & pray you can find a wiring harness on a 240SX that you can cut that wire from. Just make sure you cut PLENTY of wire to work with. Cut it too short & you're screwed!!
2). You're gonna have to figure out some sort of way to connect the two cut wires together. RGX connectors?? Hell if I know...I've never reconnected a cut 02 Sensor.
Hmm...you might be able to crimp the gold wires back together somehow then cover it with electrical tape or shrink wrap, then connect the silver braided wires together over the covered gold wires...That might work.
Anyhow, hope that helps...
ID
'95 SE

[chlatboy]

Okay that sounds very hard. Is taht the only thing i can do?