Horrible gas mileage in '99 Camry

[Atty]

I feel like I may have posted this before but I couldn't find it...

So I'm wondering, I know my Spark Plugs haven't been changed since the 50k mile mark and the manual says every 60 or so, so I bet they need changing (108k now).

Replaced the water pump, timing belt, etc, about 6 months ago.

Anything else I can do? Will changing the spark plugs help the gas mileage? Or is there something else I can do/need to do?

I want this thing to last until the bitter end so I can save as much as possible for a new car, especially because a few good looking cars are coming onto the market that I am interested in.

So AT Garage, what says you?

 

[Bignate603]

What do you consider horrible mileage, do you drive mostly highway or city?

Around 100k on many cars the Oxygen sensors begin to go. Many times this will give you a check engine light but it doesn't always. A bad oxygen sensor can make the car add more fuel, giving you lousy gas mileage.

 

[T2urtle]

^ yes... please post calculated gas mileage. not.. i get 200 miles at the 1/4 mark <~ this doesn't help anyone.

but in the end its normally the basic stuff. air filter and spark plugs are very easy to do if you have a 4 banger camry. Tire pressure set it to w/e you like above 30psi all around. maybe advance the timing on your car... all simple almost FREE things right there. that should take a horrible running car to decent. If you car was/is in bad shape you can see 3-5mpg increase just with those small adjustments that in total is about $40.

let us know what your MPG is. my 96 camry 4 banger auto is pulling in 25mpg right now well my last fill up and thats me going 70-75 on the highway. if i followed the 55 limit i should see 10-15&#37; better so ALMOST 30mpg and i'm at 114k miles.

 

[NutBucket]

Yeah, what is it? My dad gets over 32 in his '00 Camry.

EDIT: 4-banger 5-speed.

 

[Miramonti]

Have you cleaned the fuel injectors?

 

[LTC8K6]

Yes, I believe you posted before and I believe the consensus was that the mileage was okay.

 

[Atty]

Calculations this weekend put it at 17mpg. :-|

All highway miles. Barely any traffic, probably at most 30 minutes of congestion over the entire weekend of driving. Speed was speed limit, 55-70 depending on the area I was in, usually somewhere in the middle.

Did around 300 miles, filled the tank with 17 gallons (according to pump) on Wednesday morning, all was gone by Friday at about 2.

Doesn't seem right, according to the internet I should be getting 22/23avg, and I drive pretty efficiently on the highway. The bottom half of the fuel gage goes 10x quicker than the top too, idk if that means anything, or if its just my imagination. Someone once told me its because there is more air sucked in with the fuel but I don't know how real that claim is.

Tire pressure was checked Wednesday morning, air filter is brand new, and had a fresh oil change.

 

[obamanation]

My suggestion if you can is to take out all 4 spark plugs, take high quality, clear, pictures of the tips of the plugs (the part that goes into the combustion chamber) and post them online. Btw, does the car sound like it's working smoothly? You don't have any check engine lights, right? Have you been able to verify that your torque converter locks up like it's suppose to or that you don't have any transmission issues? What are the engine revs at highway speeds? If you're on the flat on the highway, say 65mph, if you press the accelerator a little bit (not floor it), does the car accelerate smoothly or do the revs jump from where they were? I say press the accelerator a little bit because if you floor it, it could cause the torque converter to unlock which will make this test void.

 

[Atty]

My suggestion if you can is to take out all 4 spark plugs, take high quality, clear, pictures of the tips of the plugs (the part that goes into the combustion chamber) and post them online. Btw, does the car sound like it's working smoothly?
Yeah, it sounds fine...

You don't have any check engine lights, right?
Nope.
Have you been able to verify that your torque converter locks up like it's suppose to or that you don't have any transmission issues?
...no? D: I know my transmission fluid needs flushing and replacing.
What are the engine revs at highway speeds? If you're on the flat on the highway, say 65mph, if you press the accelerator a little bit (not floor it), does the car accelerate smoothly or do the revs jump from where they were? I say press the accelerator a little bit because if you floor it, it could cause the torque converter to unlock which will make this test void.
3krpm. And yes, it accelerates decently for a car without any HP and weighs close to a WWII tank...

Answers in bold.

 

[LTC8K6]

The bottom half of the fuel gage goes 10x quicker than the top too

That's normal. Sometimes it's the other way around.

Why would any air be sucked in at all?

Did around 300 miles, filled the tank with 17 gallons (according to pump) on Wednesday morning, all was gone by Friday at about 2.

Doesn't sound like a valid test.

First you top up the tank and reset your trip odometer. Then you drive a few hundred miles. Then you top up the tank again. Then you do the math.

 

[skyking]

my 98 gets at least 25 in commute driving. I can get up to 30 on a pure highway run. It has 190K on it.

 

[KK]

how loud was the radio?

 

[Atty]

That's normal. Sometimes it's the other way around.

Why would any air be sucked in at all?



Doesn't sound like a valid test.

First you top up the tank and reset your trip odometer. Then you drive a few hundred miles. Then you top up the tank again. Then you do the math.

From empty to full and back down to empty isn't valid? Well, I can do another...

 

[alpineranger]

I'd say it's most likely either the O2 sensor (should throw code and illuminate CEL), or MAF sensor (won't necessarily throw a code). Spark plugs or air filter will affect the car noticeably if it's gotten to the point where the fuel economy will be greatly affected. Another possibility is dragging brakes or a trans / diff issue.

 

[T2urtle]

That's normal. Sometimes it's the other way around.

Why would any air be sucked in at all?



Doesn't sound like a valid test.

First you top up the tank and reset your trip odometer. Then you drive a few hundred miles. Then you top up the tank again. Then you do the math.

+1 on BOTH counts.

Fill up tank 100%, reset odometer to zero and drive till 1/4 or w/e you feel like. fill it up take number of miles on the odo divide by number of gals to give you a real total.

you said "about 300 miles and 17 gallons"... by you saying that most likely your not doing it right, unless you made sure to stop at 300 miles.

290miles/17 gallons = 17.05 MPG
320/17 gallons can be 18.82
or it could of been 300 / 17.25 = 17.401

you gotta do exact otherwise your complaint is indeed invalid. I have friends tell me they get good MPG or bad MPG base off how many times they fill up... Oh my mustang i have to fill up once a week VS my corolla that i can do 2 weeks. I go along because its honestly too much work to explain to someone who already thinks this way and spreads it around the work floor.


FYI... 17-19MPG is what i get on my G35 AWD sedan which is 3750lbs and i get that because i'm going 70+ mph always on it on the highway. I get 17 when i drive it the way it should be and 19 when i have my parents or children in the car. So if you REALLY are getting 17 then thats HORRIBLE for a little 2.2L engine and you should do everything you can to get it back to 20+

 

[Bignate603]

From empty to full and back down to empty isn't valid? Well, I can do another...

No, it's not valid. Unless you are running the car down until its completely out of gas you could easily be off by a gallon or more. When you refill your tank all the way up (don't top off ) restart your trip odometer or write down the mileage. Drive around until you're most of the way through the tank and go fill up all the way (again, don't top off you want this to be as near to your last fill up as possible). Record the amount of miles you went between fillups and the amount of gas it took to refill the tank and use that to figure out gas mileage.

The bottom half of the fuel gage goes 10x quicker than the top too, idk if that means anything, or if its just my imagination. Someone once told me its because there is more air sucked in with the fuel but I don't know how real that claim is.

This has to do with the geometry of the part of the thing that sits in the tank to measure the gas. You could design it so it wouldn't cause this issue but as far as I've seen most car companies don't bother.

 

[foghorn67]

Check the MAF sensor. Most of the time, this is an easy check. In fact, before you check it, buy some electrical parts dryer. Don't touch that fishing wire looking thing. Just spray it, and let it dry. Might as well do that if you go check it anyway.
Do hit up a Toyota or Camry centric forum about this. Just to be sure all proper precautions are taken.

I am also seconding o2 sensors as well. They don't always throw off a CEL.
Time is the essense here. If it is an o2 sensor, it will be much more than fuel economy getting dented. A car running rich can cause damage if unchecked. Unburnt fuel can cause oil not to lubricate so well on vital parts.

 

[Bignate603]

I am also seconding o2 sensors as well. They don't always throw off a CEL.
Time is the essense here. If it is an o2 sensor, it will be much more than fuel economy getting dented. A car running rich can cause damage if unchecked. Unburnt fuel can cause oil not to lubricate so well on vital parts.

Also, too much unburnt fuel going through the exhaust pipe can kill your catalytic converter.

 

[Bad Dude]

Take that brick out of your right shoe.

 

[SparkyJJO]

When my car hits E on the gauge, I still have about 1.5 gallons left. Most cars have a margin of safety on the low end of the gauge.

So, as mentioned, fill the tank, reset trip odometer to 0, then drive. When you fill up again, take the number of miles driven, divide by the number of gallons you put in the tank. Boom there is your miles per gallon for that tank.

FWIW, I average 28mpg and have done 32mpg in my 1998 Camaro V6 A4. It has 148k on it now.

 

[obamanation]

Well, margin or not, the point the guy is trying to make is that he is getting bad mileage which means he fills up more frequently than he should. Also, it's not that they have a "margin of safety" it's just that the tank is so large that it would be difficult to have a gauge accurately assess ALL of the fuel in the tank unless it was a narrow, long, upright cylinder or somesuch. "low" on a civic fuel gauge is very different from "low" on a Chevy Suburban.. (1.5 gallons vs 6 gallons)

 

[DVad3r]

I drive an 01 Lexus ES 300 which has the same engine as the Camry models. I recently did a tune up myself as I was having pretty bad mileage (not as bad as you but worse than what it used to be).

I ended up doing the following:

Changed spark plugs to NGK Iridium IX (130,000 km on old/original ones)
Cleaned the throttle bodies with TB cleaner
Cleaned and re-oiled my K&N filter (in your case, get a new air filter)
Cleaned my MAF sensor with MAF sensor cleaner

After all that my fuel economy is back to what it used to be and it's even better. Also my rough'ish idle at stop lights is gone and the car is just more responsive now, it feels like it's brand new again. I reset the ECU too.

Mostly city driving and some highway I get 21 MPG
Highway I get like 29 MPG

If yours is the 4 cylinder version you should be getting WAY better fuel economy. My dads 92 Camry station wagon 4 cylinder get's amazing mileage, and that car has almost 500,000 km now.

 

[DVad3r]

Oh and I also run my tires higher than the car manuals recommended PSI. Manual says 28 psi for 4 people and driving under 140 km/h. 32 for 4 people + luggage and for driving over 140 km/h.

I run my tires at like 36-38 psi regardless.