Bad MPG even after tune up - Toyota Nation Forum : Toyota Car and Truck Forums

Retrospekt · 12-08-2009, 12:13 AM

I just did a full tune up. Sparks, wires, cap, rotor, pcv, air filter, seafoam in the engine and brake booster, and oil change. Also did seafoam in the gas tank and will be doing lucas injector cleaner soon.

Before the tune up I was getting about 18mpg, now it's about 20. I do mixed driving (suburbs. Mostly go 45-60 on roads with a few red lights.) I'm light on the pedal most of the time, guilty of flooring it when I need to. (Onramp for highway, for example.)

What else could I do? Timing belt is new. Accessory belts are new. Really nothing in the engine at all is old.

gottarollwithit · 12-08-2009, 04:37 AM

Is it throwing any codes?
I don't know these cars that well, but 02 sensor or maybe a dirty MAF?.. maybe other sensors that are making it run rich?

I'm assuming it's running/driving normally?...

mazdaverx7 · 12-08-2009, 04:59 AM

next step imo, would be to change the fuel filter. next, pull the injectors and send them to www.witchhunter.com. they have a turn around time of less than a week. they are the only company i will use for injector service.

the94camryman · 12-08-2009, 12:40 PM

I'm going to say replace the fuel filter.

Hajoca · 12-08-2009, 01:41 PM

Have you looked at the thermostat? Is the engine heating up quickly?

Do you use snow tires? because snows (and winter gas) on my XLE drops the mileage quite a bit.

uibalnme · 12-08-2009, 02:30 PM

If it was a bad fuel filter(clogged), it would be having a hard time getting fuel to the engine. The car has the opposite problem. A bad coolant temp sensor(not the temp sender), and bad O2 sensors would be more likely to cause a rich fuel mix problem.

A bad coolant temp. sensor would tell the computer that the engine is cold all the time, causing the computer to spray more fuel. Bad O2 sensors would tell the computer that the fuel mix is lean, again causing the computer to spray more fuel. The recommended replacememt interval for most O2 sensors is 60,000 to 100,000 miles.

I say change the O2 sensors.

Retrospekt · 12-08-2009, 11:55 PM

I like the O2 sensor idea. The plugs in my car were ancient so I doubt the last owner changed the O2 sensors. How many are there on the car and where are they located?

Estimated cost of all of them?

Thanks.

the_professional · 12-09-2009, 12:53 AM

2 O2 Sensors.

One at the exhaust manifold under the heat shield, its once you open the hood. Really easy.

The second is after the CAT (i think?), that one requires a bit of work to reach at, someone please elaborate.

uibalnme · 12-09-2009, 01:15 AM

Well, mine is California spec., but here's a pic of the O2 sensors circled...

Basically they're the things sticking out of the exhaust system with wires coming out of them. lol

Each sensor has a different part number. One is called the upstream O2 sensor, and the other is the downstream O2 sensor. They can cost anywhere from $60 - $80 or more.

the_professional · 12-09-2009, 03:05 AM

yeah, there should be just one of those in that location.

If I recall the downstream sensor on non-cali spec cars is right under the center of the car, you may need to pull the exhaust pipe to get to it.

It's been a year since I last dealt with that area, so I am a little fuzzy.

(unless I'm nuts and there is none there? i could of swore there was.)

thaharlequin · 12-09-2009, 03:14 AM

Your car is only rated for 21mpg mixed so 20mpg is about right. If anything I think a change in your driving style and a block heater would make the biggest difference.

Retrospekt · 12-09-2009, 01:04 PM

Quote:

Originally Posted by thaharlequin

Your car is only rated for 21mpg mixed so 20mpg is about right. If anything I think a change in your driving style and a block heater would make the biggest difference.

Yeah, it's 21 mixed...according to fueleconomy.gov. I think I'll trust the numbers that actual owners of the car get. Most seem to get considerably higher than 21.

uibalnme · 12-09-2009, 05:24 PM

Quote:

Originally Posted by Retrospekt

Yeah, it's 21 mixed...according to fueleconomy.gov. I think I'll trust the numbers that actual owners of the car get. Most seem to get considerably higher than 21.

Yeah, I get ~28mpg mixed. On my last long road trip I got ~35mpg.

***MR2Jedi*** · 12-09-2009, 05:46 PM

How many miles on the car? If it's a'96 and you're getting 20mpg, you're doin' purdy good.
Run a compression check. it will give you an idea of the engines health.

uibalnme · 12-09-2009, 07:33 PM

how's 20mpg on a 96 4cyl camry good? My mom's 95 windstar with a 3.8L v6 gets 22mpg on average. Anything less than 25mpg on a 4cyl. camry is horrible IMO.