Results of 92 740 O2 sensor tests.....advice?

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geronimo

I got the new Fluke 114 DVM today and tested the voltage from the O2
sensor. this one has the averaging function and analog bar graph.

Its a new sensor from RockAuto.com. Replacing the old one had no
effect on gas mileage, it remained at 16 mpg.

After running a few minutes, at idle, I had 475 mv average, and the
bar graph was fluxing all the way from zero to over-range, about once
or twice a second.

At highway RPM, the avg. rose to abt 480 mv. and bar graph was fluxing
the same way. I think J. Sweet said that at stochiometric, it should
be abt 500 mv....so should I conclude that the control system and all
sensors are functioning properly, maintaining optimum mixture?

So then either I am a lead--foot (no way), or the tranny is not
maintaing proper ( low) RPMs (I am thinking). Like I said, It winds
up to 3300 RPM or so going up to hwy speed, and will never shift into
third until you manually back off the gas for a second--so its like
having only a semi-auto transmission. And it turns about 3200 rpm at
60 mph. I have tried twiddling with the kick-down cable a lot, and
can't seem to get the tranny to shift at lower speeds and fully
automatically with *any* adjustment.
My 88 Camry maintains LOW RPMs....while this Volvo winds up like a
top!

I was hanging on to this car beacause its its easy to work on /fix
myself.....but there comes a time when the rising price of gas will
make it better to buy a recent-model high gas mileage car, and bite
the bullet on a monthly car note to pay.

I like those VW diesel engines that get 40 or so MPG!

Thanks, geronimo
 
geronimo said:
I got the new Fluke 114 DVM today and tested the voltage from the O2
sensor. this one has the averaging function and analog bar graph.

Its a new sensor from RockAuto.com. Replacing the old one had no
effect on gas mileage, it remained at 16 mpg.

After running a few minutes, at idle, I had 475 mv average, and the
bar graph was fluxing all the way from zero to over-range, about once
or twice a second.

At highway RPM, the avg. rose to abt 480 mv. and bar graph was fluxing
the same way. I think J. Sweet said that at stochiometric, it should
be abt 500 mv....so should I conclude that the control system and all
sensors are functioning properly, maintaining optimum mixture?

So then either I am a lead--foot (no way), or the tranny is not
maintaing proper ( low) RPMs (I am thinking). Like I said, It winds
up to 3300 RPM or so going up to hwy speed, and will never shift into
third until you manually back off the gas for a second--so its like
having only a semi-auto transmission. And it turns about 3200 rpm at
60 mph. I have tried twiddling with the kick-down cable a lot, and
can't seem to get the tranny to shift at lower speeds and fully
automatically with *any* adjustment.
My 88 Camry maintains LOW RPMs....while this Volvo winds up like a
top!

I was hanging on to this car beacause its its easy to work on /fix
myself.....but there comes a time when the rising price of gas will
make it better to buy a recent-model high gas mileage car, and bite
the bullet on a monthly car note to pay.

I like those VW diesel engines that get 40 or so MPG!

Thanks, geronimo
Click to expand...

Yeah it sounds like your O2 sensor is working just fine. There's something
goofy going on with the transmission though, does it ever shift into 4th? My
740T has a manual transmission, but cruises at around 2300 RPM on the
highway and I can usually get around 27 mpg out of it.
 
Ok geronimo...

Go back to basics. Pull out your oil dipstick and look at oil level,
condition and smell it. Is it overfull ? Is it discolored ?, Is it
thin ? Does it have an acrid/gassy smell ? If, especially the latter,
symptoms are present that is an indication that fuel is burning
inefficiently and the excess is ending up in the oil. The fact that
the H2OS is working nicely suggests that this is not the case but it's
a quick way to eliminate one branch of the diagnostic tree.

Like James, I'm inclined to think that your OD is not engaging. Check
trans fluid and service if required. The transmission is not
particularly complex and mine have always provided good service with
limited attention. If you service it you might try LubeGard additive.
Every summer I tow a converted VW Type II camper with my 87 240 wagon
for 5000 or so miles and have yet to have a problem so the trans
itself is fairly reliable in my experience, but I do faithfully
maintain things.

With an AT you should get a reliable 24/25mpg and the failure to get
it into OD will keep it under 20mpg.

Keep us posted

pat hayes
 
Nope....the oil looks entirely normal. Only a little darker than honey
and no smell. That is what it is, I think... no overdirve, although
it is enabled by the button on the shifter. I have never counted more
than three gear shifts. The tranny is screwed.
 
geronimo said:
Nope....the oil looks entirely normal. Only a little darker than honey
and no smell. That is what it is, I think... no overdirve, although
it is enabled by the button on the shifter. I have never counted more
than three gear shifts. The tranny is screwed.
Click to expand...

Most common cause is the wire to the solenoid valve on the side of the
tranny.

The relay also commonly fails, though usually the orange arrow on the dash
gets stuck on when that happens, but not always.

Check the fuse too, as obvious as that is.

Internally the tranny is probably fine, these are pretty dependable units.
 
Roger on that. I will have to check all that out....our gas bill is
getting outrageous.


Check out this google video of this guy who is injecting "free" HHO
into his Accord to increase HP and MPG.....

http://video.google.com/videoplay?d...=58&start=0&num=10&so=0&type=search&plindex=0

I want to build one of these hydrolyzer cells myself and experiment,
they're pretty simple to home-brew.

I just wonder if that engine would still be running after 5000 miles
of this.....
 
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