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Old 07-07-2008, 10:03 PM   #1
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Default VE analyzer can't nail it & AFRs jumping around

i've tried logging trips, analyzing and reburning about 10 times so far and my AFRs are still all over. I made sure the LC-1 settings are correct and accel enrichment and ego correction is off. btw how jumpy should my wideband reading be? it doesn't seem to be very stable. it is usually hovering at the number +/- 0.4 or so. so if i'm at 14.7 it'll be jumping between 14.3 and 15.1, it this acceptable? i have the measurement as "instant" in the LM programmer, should i introduce a sampling delay?
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Old 07-07-2008, 10:18 PM   #2
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The level of "jumpiness" you describe in your AFR sounds perfectly acceptable. Mine actually scans a slightly broader range than you describe when at idle, where my Gego tends to tick back and forth across two to three values.

Which brings me to a point- you should leave Gego enabled all the time. MLV reads and corrects for the current Gego activity in each sample that it analyzes. In fact, it even reads and corrects for Accel Enrich. Quoth the official documentation:
Do I need to disable Gego for VE Analysis? - Gego is factored into the VE Analysis formula. Say the current table VE value for a single calculation is 50 and Gego is 110, 55 will be used as the actual VE value. If Analysis determines that it was lean for that record, the 55 value will be increased accordingly and added as a weighted recommendation. So by running with Gego on, you benefit by having both the ECM learned correction and the current O2 to use as input for correcting the table, instead of just the current O2 output. Having both is better, especially with a NB O2 sensor. So while I would recommend leaving Gego on with either a WB or NB sensor, I highly recommend leaving it on for a NB.
Do I need to disable Accel enrich for VE Analysis? - Accel enrich log records are filtered and ignored by the VE Analysis engine. So if you step through your log record by record in MLV, watch where you slammed your foot to the floor. The Accel indicator will be on, each of those records will not be used in VE Analysis, then continue steping forward the number of records you have WB delay set to +1. That is the first AFR value that will be used in VE Analysis after the accel enrich event. With the WB delay set correctly, oredmost impact of accel enrich inaccuracy will be ign. Also consider this, with Accel enrich on, there could be some residual over rich records, but if Accel enrich is disabled you have the same potential for some residual lean records. I think it is in your benefit to let VE analysis correct some of the impacts of accel enrich, if you really feel there is a section where accel enrich is causing excessive residual rich record, you should probably consider lowering your accel enrich for that area.
Do I need to disable over run for VE Analysis? - PW=0 log records are filtered and ignored by the VE Analysis engine in version 2.58 and greater.

Some additional info on how VE Analyzer operates:

For what it's worth, I still capture and analyze logs after several months of operation. Over time, I've turned down my ego step size to 1 and increased ego step duration to 60 events, so for the most part, both Gego and MLV are making relatively trivial corrections, but it does take a while to get to that point.
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Old 07-07-2008, 10:40 PM   #3
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Joe, you are a cauldron of wealth. Thank you. I wasn't even aware that this documentation existed.
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