Serial logging and tuning with 2 LC-1's

Differences in measured lambda between banks can be due to many physical things (it's not in the tune):

for example, engine is not symmetrical left-to-right or front-to-rear, each cylinder burns a little differently, each header runner is a different lenngth;

the 0.030 difference you're seeing in Lambda is small (e.g. compare 1.030 with 1.000), it's 3%;

when LTFT's are enabled, the PCM trims each bank to stoich (lambda 1.000) so you won't see as big a difference;

if in OL (LTFT disabled) you're seeing lambda 0.970-0.990, you would make B3605 or B3647 leaner by 0.010-0.030 (which is a very small amount, you might now overshoot).

Quote:

---

Originally Posted by joecar

if in OL (LTFT disabled) you're seeing lambda 0.970-0.990, you would make B3605 or B3647 leaner by 0.010-0.030 (which is a very small amount, you might now overshoot).

---

To expand: This is also the case in closed loop. Even with the trims adjusting it tends to stay in the afore mentioned range if just a little bit closer to 1.000.

The PCM uses the same tables to calculate air/fuel for each bank...

it uses separate trims to trim each bank...

so any differences between banks can be attributed directly to differences in the O2 sensors, or differences in exuast/intake betweeen the banks, or cylinder-to-cylinder differences.


Did you try swapping the front O2 sensors across banks...?

no, I didn't consider that it may be the WBO2's. I'll have to do that.

I wonder if there is something weird going on with one of the LC-1 units since they are simulating the NBO2's? I'll try swapping the WBO2 sensors first and then I'll swap the LC-1 brain if I have to.

I didn't swap my sensors yet but I was just looking at my most recent log with both lean cruise and dfco disabled and I'm seeing more of those weird maxed out blips on my serial LC-1 reading. It seems to effect both banks and the mV read-out from the simulated narrowband is effected as well. This seems really strange to me but I don't have any LC-1 experience to work from so I don't know. Please review this log when you get a change.

Noted areas are as follows:
Frame: 1373 (both serial banks spike ridiculously lean @ 7.3 lambda and 15.5 lambda. Not sure of any effect on the mV reading)
Frame: 7048 (both serial banks spike ridiculously lean @ 17.5 lambda and 32.5 lambda. Very obviously reflected in the mV reading)
Frame: 9230 (both serial banks spike ridiculously lean @ 7.9 lambda and 23.4 lambda. Not sure of any effect on the mV reading)
Frame: 12161 (One serial bank goes lean and one goes rich @ 10.0 lambda and 0.00 lambda. Not sure of any effect on the mV reading)

Maybe this isn't as strange a thing as I think it is but I figured it's worth looking into.

As a side note, charting the mV read-outs for the two simulated narrowbands gives a good visualization of how one bank is almost always more lean than the other.

Attachment 13473
Attachment 13474

The thing to do might be to drill/weld the extra bungs into the headers so you can run both the NBO2's and the WBO2's and see what happens.

hmm, yea I guess I may have to consider doing that. It's strange though, I don't feel the spike while driving. Also, just the fact that sometimes one side goes lean and one goes rich while other times they both go lean, it seems like it has to be a problem with the lc-1's. Maybe I'll go register at the Innovate forum and post something over there.

Let us know what Innovate says.