VERY Bad Gas Mileage '97 Altima

Rabbit · Aug 29th, 2004, 06:30 PM

Howdy all!

Though I'm a newbie here, I'm really an old f@rt with some grease under my nails.

Recently picked up a used '97 Altima for my daughter to replace the civic she totalled. The car runs great and my mechanic checked it over and only replaced the plugs and alternator belt. He said everything else checked out OK.

The gas mileage is <10mpg around town and I know that can't be right. What should I be checkin?

Also, someone told me that if all doors unlocked when the key was turned twice clockwise in the driver's door that I could get a remote lock switch to work. I got one off eBay and can't get it to work following the instructions provided. How can I check to see if the locks will respond to a remote? If they will, what do I have to do to get this one to work?

Thanks for any and all help. It will be greatly appreciated and gratefully received. (Please be gentle since it's my first time

Catman · Aug 29th, 2004, 07:15 PM

One thing I can think of is a lazy O2 sensor, that is not bad enough to set off the Service Engine Soon light. Another, my mechanic put some Bosch plugs in my car and they fouled out. Performance and fuel economy did not return until I put the stock NGK plugs back in. Maybe the timing is off, or your daughter has a lead foot. (Just kidding). There may be other things, but I am not experienced enough to help you more. Welcome to the forum. I am not so young myself.

Rabbit · Aug 29th, 2004, 09:00 PM

[quote=Catman]One thing I can think of is a lazy O2 sensor, that is not bad enough to set off the Service Engine Soon light.]

Is this an owner service item or must I go to a garage or dealer? At first I thought my dau's lead foot might be the problem but I've kept it for a week and found the same result. Should the overdrive be on or off for in-town driving?

On another forum, someone suggested that a bad fuel pump might be the cause. Any idea how I might check this out?

Thanks again for the reply.

Rabbit

Catman · Aug 29th, 2004, 10:51 PM

I think you have OBD ll. On one car I have the Service Engine Soon light went on at 75,000 miles. I took it to the dealership (I have a warranty) and it was a lazy 02 sensor. It was replaced under warranty. My gas mileage may be up a mile or two per gallon. Now, if you had an Engine light on you can take the car to Auto Zone and have codes read for free if it has OBD ll. But, since you do not have a light, you may or may not have a problem with the O2 sensor. My car is OBD l. On my Sentra I just replace the front one when doing regular maintenance since it does not set a code on my car when it is bad. I use a special socket. It is easy to replace if you have that tool, at least on my car. It may be good to go to a mechanic that knows Nissans or go to a dealership for diagnosis. Otherwise, you may just be throwing parts at your problem. It sounds like something major is wrong to get mileage that poor. By that I mean the timing is way off or the fuel mixture is way too rich. I just read a post regarding a 95 Altima and they were getting 20 + per gallon. I don't know how to test your fuel pump. Sorry.

I have left my car in overdrive for almost 7 years. I get better fuel economy and my transmission is going strong after 166,000 miles. It may help some with the fuel economy. I do a lot of city driving.

I really don’t know your car, so you may want to post your questions in the Altima section for a U13 instead of the general section. I subscribe to Alldata online, but the procedures for testing your car may be different than mine. I know other Sentra owners have similar problems I have had. You may find other Altima owners that have dealt with the same problem you are having. They may not read the general section. Hope it works out for you!

**Asleep** · Sep 4th, 2004, 02:41 PM

Do the usual - plugs (ngk bkr5-11e gapped to .045), wires, cap and rotor (oem from the dealer), check and set the timing (20 degrees btdc +/- 2). also replace the air filter and fuel filter. you should be getting anywhere from 20-24 mpg around town to about 29-30 on the highway. dont forget to also reset the ecu and to check it for codes. you can find instructions on how to do that in this forum.
Welcome to the board and dont hesitate to ask questions if you cant find what you need in a search.

Rabbit · Sep 5th, 2004, 12:51 AM

Quote:

Originally Posted by AsleepAltima

Do the usual

Thanks for the reply.
I'll give those items a check.

I have 2 more ?'s, too:
1) Can I tell by the VIN what type diagnostics I have? (I understand the '97 had 2 different versions; true or false?)
2) Can I tell if the unit has a sensor for a remote lock? The doors all open when the driver's door is turned twice.

Really appreciate the help. Haven't had a Nissan product since my '70-something 810 wagon (GREAT machine).

rabbit

**Asleep** · Sep 5th, 2004, 02:42 AM

95 and on are obd2. i know the ecu changes from 95 on and again, i think 97.5 but im not positive... as far as the vin goes, i think it might indicate the trim level but again, im not positive.