Running lean. (well some of the time)
 

Ok, so here's my problem. About a week ago I started throwing code, 22. Right knock sensor. And 2 days ago I got a code 32. Right O2 sensor reading odd.
Now I have an A/F gauge. Just your average "ping pong" type Autometer one, but good enough to make guesses by. Of course I had it running on the LEFT O2 sensor...
So I hooked it up to the right one and sure enough it was running lean...way lean.
Which I assume could account for the knock sensor(I had hoped it was a bad knock sensor, but maybe not)tripping.
So, I checked the fuel injectors. All good.
I replaced the FPR with my parts one.
Started it up and still lean.

This morning however on my way to work it was fine. "ping pong" through stoich just like the right bank.
And then on the way home the same. Right where it should be.
After I got home however I started it up(within 10 minutes)and it was back to lean.
Actually threw another code again.
Shut it off and started it up several more times and it wouldn't leave "lean".
So it seems like once it warms up something causes a lack of fuel?
Until it cools off.
Could this be a bad O2 sensor?
I had read here that a slipped timing belt might cause a lean condition, but I don't see how restarting it when warm would relate.

Any help would be appreciated, as I don't want to go throwing codes and detonating after every time I get gas and start the car again...

That would be a bad O2 sensor. The ping pong you see is a real phenomenon. It happens only at low throttle positions where the engine is running in closed-loop. The ECU is reading the O2 sensor and making adjustments to the afr. When the O2 sensor goes bad, then the ECU cannot make the necessary afr adjustments.

Well, I WAS hoping that. Since the car has 147k on the clock.
BUT I just went out and swapped the O2 sensors(left to right) and it is still doing it. Lean on right, and normal on left...
If the ECU were seeing an overly lean mix wouldn't it compensate by dumping more fuel into it? Wouldn't that actually deter knock?

And when I say that I checked the injectors what I should have said is I used a crude home made stethoscope and they were all ticking. I also checked the resistance across the FI terminals(11.3-11.4 Ohms), and verified that they were getting 11V+.
Is there any other way to check them easily?

I'm assuming that a vacuum leak wouldn't be affected by temp?

What about the EGR system? It is on that side.

Sorry for all of the uneducated guesses, but I just don't see why it would all of a sudden go lean just because I restart it after it warms up.
It's not a gradual thing as far as I can tell(I haven't gone on any long trips) it's just fine, I shut it off, immediately restart it, and it's lean until it cools off.

Sigh...I really was hoping it was the sensor...

The EGR system feeds both halves of the engine. There is a passage in the intake manifold that sends exhaust gases to both sides of the engine.

When it goes lean, does the "ping-pong" effect no longer occur?

Correct, when it goes lean it no longer bounces. It just stays put about halfway between "off the scale low", and stoich.
I know the A/F gauge is not wideband, and not really a diagnostic tool, but as I said it's good for making guesses...i.e. normal or not normal...

After I changed the FPR it drove different. Stronger, smoother, and the right side was "normal" on the gauge. Of course I don't know what it was before because I had the gauge on the left side.
But anyway, I also changed the starter a day before. At which point I had the battery unplugged. Clearing the ECU...
So the difference in driving may be that.

I'm just going to drive around for a couple of days with the O2 sensors switched and see if I get any codes on that side.
Maybe it was the FPR.
Maybe you are right and it is the sensor. I hope so. An easy fix, and relatively(for this car) cheap at $65.
I also have a long trip coming up so I can see if it's(whatever IT is) affected by heat soak.

Thanks, though for the help!