In alt.home.repair, on Mon, 30 Oct 2017 20:00:12 -0500, Paul in Houston
TX wrote:

micky wrote:
In alt.home.repair, on Sat, 28 Oct 2017 19:47:15 -0500, Paul in Houston
TX wrote:

micky wrote:
I have a 2005 Toyota Solara SLE, 133,000 miles, with P0171 and P0174
codes, lean mixture in both banks, and a check engine light that returns
soon after being cleared.

What are the O2 sensor(s) readings?
Can your scanner read or map the O2 voltages?
If not then use your dvm on the leads.
Check when HOT! 2k-3k rpm.

I think this is what you mean:....
----------------------
Equivalence Ration (lambda)(Bank 1-Sensor 1)0.993
Oxygen Sensor Voltage (Bank 1-Sensor 1)(V)3.299
Equivalence Ration (lambda)(Bank 2-Sensor 1)1.010
Oxygen Sensor Voltage (Bank 2-Sensor 1)(V)3.307
----------------------
Equivalence Ration (lambda)(Bank 1-Sensor 1)0.992
Oxygen Sensor Voltage (Bank 1-Sensor 1)(V)3.300
Equivalence Ration (lambda)(Bank 2-Sensor 1)1.094
Oxygen Sensor Voltage (Bank 2-Sensor 1)(V)3.553
----------------------

So what they call voltages are more than zero and less than 12, and go
up and down around 3.1 to 3.6. So does that imply they are good?

I was going to take the connector apart and measure the resistance, but
it looked like I had to take off the air intake "funnel" first, and
then, it seems, the car started working right!

I went back and reread your original post.
All the numbers were there. I was my mistake for overlooking them.
The numbers look just fine. A bit on the rich side but that is probably
due to the low engine temp ~150F.
Don't really see anything wrong.

That's good. There must have been some vacuum leak, and I suppose it
will reappear**.


What I should do is use the scan tool to get the same sort of readings
when it's working right, and maybe I can find one or more values that
are different from when it was working wrong, and maybe if/when it
starts working wrong again, someone can sit in the car watching just
that/those values, and when I fiddle with the right hose, or blast the
right 02/fuel sensor, he's see the change and tell me.


**After all, it showed up in March when the previous owner had it, then
in October. The mechanic who looked at in March might have touched the
same hose or whatever I touched. Actually, the CEL and the VSC and
Trac*** lights were all on and they all went off a day or two after I
bought the car. Then when I was playing with the transmission, putting
it in first gear to go down a steep but short hill, the light went on
and it's been on almost all of the time since then.

***The owners manual says that the Trac (Off) light will come on when
the VSC light is on. But still, maybe I should have mentioned the other
two lights. I apologize, although I was only hurting myself.

I think this was a very good thread. Even if what I learned didn't
directly fix the car, I still learned a lot.