O2 sensor?

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Old 24 Dec 2005, 08:12 am   #1 (permalink)
Stubby
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Default O2 sensor?

Is there any special trick I need to know about to replace the oxygen
sensor on my '95 4-cylinder Camry? My mileage has dropped to 24 mpg
and a friend suggested replacing the sensor will improve it.
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Old 24 Dec 2005, 09:03 am   #2 (permalink)
m Ransley
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Default Re: O2 sensor?

There are alot of things covered in a tune up to affect milage, 1st is
cold weather. Putting it on a scope will determine if o2 sensor is bad.
Second check timing. After a regular tune up and synthetic oil
everywhere even differential, trans and power steering once I went from
20-30 , alot of small issues affect 4 cil toys.

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Old 24 Dec 2005, 09:07 am   #3 (permalink)
m Ransley
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Default Re: O2 sensor?

Cold midwest US weather always drops my milage easily 20%+.

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Old 24 Dec 2005, 09:44 am   #4 (permalink)
Stubby
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Default Re: O2 sensor?

m Ransley wrote:
> There are alot of things covered in a tune up to affect milage, 1st is
> cold weather.

That happens every year. I'm near the MA-NH border and it does get cold
here.

> Putting it on a scope will determine if o2 sensor is bad.

Cheaper to just replace it ($20).

> Second check timing.

Nothing has changed the timing in 10 years. I'm not going to noodle it.

> After a regular tune up

Modern cars don't have anything to "tune up". The computer(s) take
care of it. You twist 1/4 turn and the computer twists 1/4 the other way!

Maybe new plugs will help however. 146,000 miles on the first set. I
could have a bad one!

> and synthetic oil
> everywhere even differential, trans and power steering once I went from
> 20-30 , alot of small issues affect 4 cil toys.

Yes. Different lubricants might improve the mileage, but doesn't
account for the decrease.

I just discovered that my tires are a bit soft. I'm sure that accounts
for a bit of the decreased mileage.

Thanks for the check list. I'll bet plugs and airpressure will bring
the charriot back to normal.

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Old 24 Dec 2005, 10:28 am   #5 (permalink)
m Ransley
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Default Re: O2 sensor?

Gee stubby you have alot to learn , timing belts stretch retarding
timing, retarded timing lowers plug cilinder temp, increases pollution,
carbon buildup, mileage and reduces power. A 3-4 degree retard on my 4
cil, and 3-4 is normal on a belt of 60000-80000, reduced my power
dramatcly and mpg by exactly 4 mpg, yes Four.

Old plugs electrical resistance to fire increases and electrode wear
affects burning and combustion efficiency , as well as it affects timimg
when gaps widen enough. If I replace a 30-50000 mile set I feel more
power and see 1 - 2 mpg every time.

Wires increase resistance as they age, caps carbon track and pit as
does the rotor, I easily get 1 mpg on a new set.

A bad PVC valve can cost you 1-3 mpg from not recycling blow by and
ruin oil fast.

A dirty intake causes loss of power

An old thermostat that opens early or never cloes will loose you easily
10 % milage when its 10f out and you drive short trips.

A weak coil not providing blue spark will cost you in milage.

Old calipers can stick causing brakes to drag, and the list goes on.
The computer only adjusts within a parameter it cannot make up for
timing being off as mechanical timing is its set point. I got my 4 cil
91 up to getting 36 last summer on a few trips, down from a low of 20-21
in winter, there is indeed alot you can do. Normal ran out 9 years ago
on your 95, noodling as you say only restores factory parameters. After
market wires and thermostat are crap, I never get more than 30000.
Synthetics like mobil in trans, differential and motor will alone see
you 3 mpg, With my 91 every day in summer I get 28- 31, 35 on trips, but
winter is another story

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Old 24 Dec 2005, 11:14 am   #6 (permalink)
Stubby
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Default Re: O2 sensor?

m Ransley wrote:
> Gee stubby you have alot to learn ,

I know that.

> timing belts stretch

Is it a belt or a chain? I actually have that changed every 100K, but
that's not a "tune up". I get a new water pump at the same time.

> retarding
> timing, retarded timing lowers plug cilinder temp, increases pollution,
> carbon buildup, mileage and reduces power. A 3-4 degree retard on my 4
> cil, and 3-4 is normal on a belt of 60000-80000, reduced my power
> dramatcly and mpg by exactly 4 mpg, yes Four.

OK. I'll find my old timing light and check it. How many degrees is
right?

>
> Old plugs electrical resistance to fire increases and electrode wear
> affects burning and combustion efficiency ,

If the gap is wider, it will indeed take a higher voltage to breakdown
the gap. But if the coil is good, the difference won't matter. 30kv is
going to make a spark no matter. Try holding a plug wire near the
engine so you can see how far the spark will jump.

> as well as it affects timimg
> when gaps widen enough.

I don't see how the very slight difference in the time to jump the gap
can affect the timing. How many microseconds will, say a 50%, gap
increase delay the spark and thus the timing?

If I replace a 30-50000 mile set I feel more
> power and see 1 - 2 mpg every time.

You're lucky.

> Wires increase resistance as they age, caps carbon track and pit as
> does the rotor, I easily get 1 mpg on a new set.

Wires normally run about 100K. When they get "bad" according to
friends, I've measured them at 1M. When all else fails, I'll change the
wires.

> A bad PVC valve can cost you 1-3 mpg from not recycling blow by and
> ruin oil fast.

Good point. I'll replace the PCV and try it out.

> A dirty intake causes loss of power

True. Whenever I find air filters on sale I change it. Probably once
1 year but I've never been able to say that it increased my mileage.

> An old thermostat that opens early or never cloes will loose you easily
> 10 % milage when its 10f out and you drive short trips.

As long as the heater works and the engine comes up to temp, I assume it OK.

> A weak coil not providing blue spark will cost you in milage.

True, but coils really don't fail often. You can test it by turning
off all the lights and running the car in the dark. Any sparks or glow
means it's bad. I knew a guy that used to insist on "cleaning" his coil
with all sorts of solvents. I believe he was actually providing a
conducting path!

>
> Old calipers can stick causing brakes to drag,

Yep. The brake heats up and you smell it! I've had that happen.

and the list goes on.
> The computer only adjusts within a parameter it cannot make up for
> timing being off as mechanical timing is its set point. I got my 4 cil
> 91 up to getting 36 last summer on a few trips, down from a low of 20-21
> in winter, there is indeed alot you can do. Normal ran out 9 years ago
> on your 95, noodling as you say only restores factory parameters. After
> market wires and thermostat are crap, I never get more than 30000.
> Synthetics like mobil in trans, differential and motor will alone see
> you 3 mpg, With my 91 every day in summer I get 28- 31, 35 on trips, but
> winter is another story
>

I think I would like to own an auto parts store in your town!
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Old 24 Dec 2005, 12:00 pm   #7 (permalink)
Curtis Newton
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Default Re: O2 sensor?

On Sat, 24 Dec 2005 09:12:01 -0500, Stubby
<William.Plummer-NO-SPAM-@alum.mit.edu> wrote:

>Is there any special trick I need to know about to replace the oxygen
>sensor on my '95 4-cylinder Camry? My mileage has dropped to 24 mpg
>and a friend suggested replacing the sensor will improve it.



Where are you located? Does the area you are in run oxygenated fuels?
I always get reduced mileage with the winter fuel blend here in
Colorado.
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Old 24 Dec 2005, 12:56 pm   #8 (permalink)
Daniel
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Default Re: O2 sensor?

Before you replace the O2 sensor, test it.
the factory service manual gives the procedure.
use the OX1 terminal on the underhood DLC (date link connector) near
the passenger (US) side strut tower
one side of a VOM probe goes to the terminal, and one side to ground,
then you count the number of fluctuations over time to see if the O2
sensor needs replacement

see: http://camry.turboninjas.com/

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Old 24 Dec 2005, 01:43 pm   #9 (permalink)
m Ransley
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Default Re: O2 sensor?

For airflow I meant a dirty throttle assembly , at least that is what I
think its called on a 4,

I dont know timing for your year. If you only have 20 thousand or so
im sure its ok but checking is always a good idea, be sure to short the
proper terminals.

Coils on the 4 are a known issue of problems.

For temp its something you will notice that it takes longer to heat then
it used to.

I actualy have poor auto adjusting on one rear brake and it adjusts
till there is drag, something I have to fix, and I get no smell..

Point is alot of little things add up on the 4, nothing I really notice
as bad but when done my mileage improves, as another noted winter gas
mix can hurt mpg, but bigest factor is just the cold short trips.

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Old 24 Dec 2005, 02:41 pm   #10 (permalink)
Stubby
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Default Re: O2 sensor?

Daniel wrote:
> Before you replace the O2 sensor, test it.
> the factory service manual gives the procedure.
> use the OX1 terminal on the underhood DLC (date link connector) near
> the passenger (US) side strut tower
> one side of a VOM probe goes to the terminal, and one side to ground,
> then you count the number of fluctuations over time to see if the O2
> sensor needs replacement
>
> see: http://camry.turboninjas.com/
>

Thanks. I snatched the whole manual, also. That will save some trips
to the library, not to mention copier expenses.
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