Quote:
Originally Posted by tpepmeie
I've seen the same thing. The issue, in my case, was that the CTS was warm enough to go Closed Loop (~47C), but it wouldn't enter learn mode until even hotter. Finally determined that there was still a bit of enrichment occurring up to 68C. The learn mode only enables if commanded lambda = 1 (14.7), ie no enrichment.
Not sure if that will help, but you might look at it, and zero the OL enrichment above 56C or so.
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Todd,
Correct on all counts. No the ACCEL chart does not include PW correction. I suppose for larger motors w big injectors it may be a factor. Reviewing my logs,
I didn't find any PW that approached the numbers in that table. The smallest being at idle ~ about 4ms. So I didn't worry about that table. At first I thought perhaps that table was dealing w a delta in the PW but that was incorrect.
In playing w the IB/V table, I in fact found a marked improvement in BLM split.
Less so at idle conditions but even there the delta between the two banks was
decreased. However, at cruise it appeared to really make a difference. As I posted earlier in the thread, my overall BLM is averaging 129 for L/R, w a
133/125 split as of the last tune. Frankly, I'm pretty happy w that. In some places, as in higher RPM areas of the VE table, L/R are identical. To some extent, I consider that the larger cams also contribute to the L/R differential. A small variation in cam timing could contribute to the BLM split as well. I can only tell you what I observed when correcting the IB and can't unequivocally point to a causal relationship. However, when I "overcooked" the IB, the split deteriorated. So it seems as if there's a sweet spot.
Regarding the C/L flip flop, I ran into the issue you described about 2 years ago. Playing w the O/L v CTS table, it would go C/L but no Learn no matter what the temp. Well I determined that the Commanded O/L AFR had to be = to the O/L Offset in the constants. Richer than that and it would override Learn. In my case, that's an AFR of 13.67 at 80C. Took me a while to figure it out. That would suggest having the AFR =13.67 at 68C has Learn come on sooner. Would be great to have an ECM bench setup.
The issue I am having now is that C/L will check on/off at times. Looking at the logs, it's happening at low MAP ( so trailing throttle or decel) and I can see the O2v go lean. I have lowered the O2 window at low gm/sec. to address the rich idle issue you get w larger cams. This was actually causing the Code 44 I was getting at times while idling.
I finally figured out that I was forcing the O2 below the .2v threshold long enough to set the code. Raising the window eliminated the code. So now my suspicion is that the O2v voltage is dipping below the C/L window I just raised long enough to take it out of C/L. If I hit the accelerator, it goes back into C/L.
I am thinking that if I lower the Prop Gain, I can decrease the extent of the voltage swing and keep it within the C/L O2 window. Haven't had a chance to try it out, but I usually reduce prop gains, particularly at idle. Someone suggested narrowing the C/L window but wouldn't that make the problem worse?
Prior to this, I was noticing in the logs that my O2 signal was dropping off intermittently causing the ECM to think very lean(might explain some of the BLM issue). Sometimes it was only a few frames, sometimes a whole string. And it was only on the right side, where I have the O2 harness extension because of the headers. Made a new extension and validated the O2 signal and heater circuits. No more dropout.
Beyond the BLM split, having more accurate IB compensation significantly reduced the number of Learns needed to get the tune right. Within 5 or 6 cycles I got to where the VE changes calc'd were within .39% just about anywhere in the table. So no reason to keep going. Once I incorporate these latest IB values, should be interesting to see how much change there is in the VE. At least, it's moving in the right direction.