I logged my drive home yesterday, and I found that my left bank runs lean, and my right bank runs just right. I exported the data, and my LTerm-LC (left side) counts spend most of their time at 144, and the right side sits right around 132. My STerm counts stay fairly close and aren't split like the Lterm counts are.
My question is, what would cause this? Could I have a small exhaust leak that is causing the lean condition on the left side, or what else could it be?
Also, my O2's are all over the place with voltage. When I say all over, they will drop to say 68mv and then right back up to 700mv. They are not holding steady at all. I'm wondering if this is normal, or if there is something wrong with them. They are only 2 years old, but I don't drive the car much either.
Does anyone have any suggestions as to what my problems may be?

Thank you.

 

Its completely normal for o2's to bounce around, that is how our pcm is setup. The short terms being near 128 just means that the engine is not requiring any further adjustment in fueling for that side. Ie by what the sensors are reporting says with that adjustment the car is at stoich now.

The lean blms can be a number of things, clogged injectors, missfires, vacuum leak, exhuast leak, bad sensor etc. Could even be a problem with the wiring back to the pcm.

 

I'm wondering if it's an exhaust leak. I can hear it if I drive the vehicle, shut it off and it cools off a little and then I drive it again. Once the exhaust manifold is warm, I don't hear it anymore, but I know it's there. It would make sense because it shows my left side as being really lean up to around 3600 rpm, and the right side is right where it should be the entire time. I picked up manifold gaskets last year, but I'm really not looking forward to changing them. I can post my counts if anyone wants to see how far off they are and if there may be something else I need to look at.

 

If you post a link to a .csv file of the data log, anyone can look at them for you.

 

I know that this is old, but I FINALLY have the car out and was able to do some logging on my way to work this morning. But, since I'm at work, I can't put the file up on any hosting sites, so would anyone be willing to look at it if I can e-mail it to them?
I still get the split BLMs, but the knock retard doesn't seem to be as bad. But on the other hand, if I can get 15 mpg I'm doing good. I don't know what's going on, but the gas mileage has been horrible! The O2's are only 3 years old with maybe 20K miles on them, and everything else seems okay, other than I need to get my valves lashed correctly (I went 3/4 of a turn, and they don't like that, so I am going to go a full turn - stock rockers). Hopefully the log will show something that I am missing.

 

Does anyone want to take a stab at it?

 

Well, it looks like I may have found the problem. When I had adjusted my valve lash last year, I set them to a 3/4 turn. It was loud and I felt that the car didn't run as well. When I logged it, I was getting spark retard, some knock, and the BLMs were off. Last night, I re-lashed all of the valves and went 1 full turn past zero lash. I immediately noticed a difference, as the car seemed to idle more smoothly, and wasn't as "loud" (valve train noise).
This morning, I logged it on my way in, and surprise, surprise, the spark retard is gone, the knock counts are gone, and at 68-70 mph, the LT BLM counts hover between 123-130. Between each side, they only vary by a number of 1 or 2.
Now it's on to worrying about important things, like headers!