# Fuel economy



## Leuthesius (Sep 7, 2006)

I own a 1995 Altima GXE

It has 207,500miles on the original engine.

I have been getting really crappy fuel economy lately and I have not been able to lock down the problem.

I have recently replaced the belts, the plugs, the plug wires, air filter, fuel filter, fuel pump, muffler, transmission, cv axles, control arms, joints, ball joints, tie rods, tires, wheels, wheel hub assemblies (front), calipers, brakes, rotors, radiator, battery, starter, and alternator. Next on my list is to replace my AC lines and condenser, vacuum the system, and refill the coolant.

I do all of the work myself so I don't have to pay a shop for it. 

The car runs fine (and never really ran crappy). It is just getting incredibly crappy mpg. I have gotten 35+ out of this thing and now I am averaging around 20-22. 

Ideas?


----------



## Darktide (Jul 29, 2004)

I'd replace the O2 sensor just for kicks. Get the universal. It'll cost you $20 and only a few hours times (because of the stupid heat shield). That's the only thing I could think of. 

Darktide


----------



## Leuthesius (Sep 7, 2006)

O2 sensors are only about 2 years old. And its about $200 for both.


----------



## Darktide (Jul 29, 2004)

the 95 could have had 2 heated or 1 not heated O2 sensor. Sorry. The 94 I worked on only had the 1 non heated. Other than that I can't think of anything that would give you serious driveablilty issues other than internal engine wear. And even then for that much of a drastic change you should've noticed something. 

Have you changed your driving situation from the 35+? What I mean is was that pure highway and now all your drive is city? It could make a drastic difference.

Darktide


----------



## Asleep (Jan 19, 2003)

o2 sensors are not time sensitive, they are mileage sensitive. you should change them right around 55-65k miles. is your o2 sensor on your 95 a single or triple wire sensor?
if its a single wire, its only 38 bucks for an oem style bosch sensor that goes on the exhaust manifold. not sure about the cost for the rear sensor my 94 doesnt use it.


----------



## Asleep (Jan 19, 2003)

good call btw dark on the sensor.


----------



## Darktide (Jul 29, 2004)

if he's got both he has to have a 3wire sensor. The 1wires only use one sensor (or that's the trend I've seen). Must be seeing some heavy use to go 50k in 2 years though... but then again nothing says the sensors could be failing early. When I was with Advance I didn't find Bosch to be that great in the O2 sensor department.

Darktide


EDIT - thanks Asleep


----------



## Asleep (Jan 19, 2003)

i have to vouch for the bosch sensors. they withstand nitrous use very well. they also happen to be original equipment for an altima...


----------



## Leuthesius (Sep 7, 2006)

Hrmm.
I'm replacing my catalytic converter, since I found a stock one for $70 (dealership says over $200, thieves).

When I do that, I'll replace the rear sensor. It's a bosch three wire. The one on the manifold I believe is a single.


----------



## Darktide (Jul 29, 2004)

I was going to suggest the cat but if its gone bad you should've noticed some issues. You obviously are mechanically inclined enough to feel issues coming a long way off which is why i'm confused as to what it could be as anything to hurt your fuel economy that bad should be doing something. Well, one thing, have you checked your tire pressure? Sounds stupid but it has a big effect. And if all 4 are low you may not detect a pull and you'll certainly be hurt in the economy area but you should be able to see it/hear it/feel the overall drag. Maybe the busted CV Shaft is bringing you down? I'm at a loss on this one. good luck and keep us posted.

Darktide


PS - Especially on the slight pull to the right. My wife's Contour does the same damn thing and I can't figure it out. We've had the tires rotated, wheels aligned just fine, all tire pressure fine. But when I drive it my lower back hurts from constantly re-adjusting the wheel. Its pretty bad on her car but I always thought "cheap POS ford" but apparently I may be only slightly right.


----------



## Asleep (Jan 19, 2003)

Leuthesius said:


> Hrmm.
> I'm replacing my catalytic converter, since I found a stock one for $70 (dealership says over $200, thieves).
> 
> When I do that, I'll replace the rear sensor. It's a bosch three wire. The one on the manifold I believe is a single.


you can actually probably get it done at an exhaust shop for a good price. i got mine done for 110 installed at a local shop. not a bad price imo.


----------



## Leuthesius (Sep 7, 2006)

Yeah, I'll be buying mine for $70 + shipping, and taking it to the mechanic at seeburg to take care of for about $20. So about the same price. The problem is getting one with the O2 sensor hole.


----------



## LONDONDERRY (May 19, 2004)

Alseep and Dark tide
Since where on the subject of 02 sensors. I have a question.

What makes them go bad in the first place? And why replace them at mileage intervales? Currently, the two I have never been replaced and I have 200,000 miles on my Altima. 

Frank


----------



## Asleep (Jan 19, 2003)

ive never looked inside of one but im guessing that either the filament inside gets worn away or it gets carboned up over time. i think they go by mileage constraints because mileage would actually contribute to the wear on the sensor where as time wont.


----------



## Darktide (Jul 29, 2004)

Asleep is pretty much on the money. Since the functional part of the O2 Sensor is tucked into the exhaust pipe its safe from the elements so it can stand the time. They actually don't go bad all of a sudden, they gradually get sluggish over time until its doing such a bad job that you get the drivability problems. I'm very surprised that you haven't changed either one yet as OEM normally crap out around 100k though i'm at 104k and running strong as ever. 

Darktide


----------



## LONDONDERRY (May 19, 2004)

Darktide said:


> Asleep is pretty much on the money. Since the functional part of the O2 Sensor is tucked into the exhaust pipe its safe from the elements so it can stand the time. They actually don't go bad all of a sudden, they gradually get sluggish over time until its doing such a bad job that you get the drivability problems. I'm very surprised that you haven't changed either one yet as OEM normally crap out around 100k though i'm at 104k and running strong as ever.
> 
> Darktide



I'v yet to replace some parts that normaly wear out over time. For example, the water pump assembly, CAT, MAF, and O2 sensors. Then again I'm comparing this to the past cars I use to own. 1989 Chevy Beretta, 1983 Monte Carlo. 1981 Buick Regal. 
Thanks for the tip on the O2 sensors, maybe I'll replace them during national car month, which is coming up
Frank


----------



## Leuthesius (Sep 7, 2006)

I'm not so sure anymore. I took a 420 mile trip with gas to spare. I averaged 33.5mpg. I guess I just needed a good highway run. Course, I only ran at about 2500 rpms the entire way, so about 61-68mph.


----------

