Why Multiple Column PIDs for B5913?
So I felt like I recalled off-hand that it was dyncylair_m/dma that was the value I needed to log but I logged both for the hell of it. I wasn't seeing a row or column label to give me that warm fuzzy with V8, but noticed a feature to link to scan tool, so I did that. Now when I'm on B5913 I can choose from either dyncylair PID which doesn't seem right. Here's a snippet from Paul from eons ago:
Quote:
It's been a long time since I looked at the LS1, so hopefully I am remembering this correctly (feel free to correct me if I'm wrong).
For LS1, I would use CYLAIR_M or DYNCYLAIR_M depending on the requirements below. The "_M" (or "_DMA") suffix indicates PIDs that are not normally available from the ECM. EFILive has analyzed which memory locations are used to lookup the data in various table and the _M PIDs report the exact value used by the controller for table look-ups.
Requirements:
CYLAIR_M is available when a MAF is fitted and fully functional - it is computed based on the MAF values.
DYNCYLAIR_M is available when the MAF has reported a fault code - i.e. when a MAF is not fitted (or faulty) - it is computed using the MAP, RPM and IAT values.
Note: DYNCYLAIR (without the _M suffix) is a predicted value that the PCM computes from a number of sensor inputs (MAP, RPM, IAT etc). I can't remember (don't know) why it needs to predict the g/cyl ahead of time, I think it is 2 ignitions cycles ahead. It then uses (averages?) the around 5 predicted and past values to arrive at the value used for the lookup (i.e. DYNCYLAIR_M). So you may see very small discrepancies between DYNCYLAIR and DYNCYLAIR_M - I don't think the discrepancies would be significant, except maybe during a high rate of change of airflow, like transitioning from 0% throttle to 100% throttle instantly (or vice-versa).
Regards
Paul
It seems wrong that I can select more than 1 PID here, is there a utility that I'm not seeing? I remember years ago logging the wrong one and really chasing my tail on my dually when I brought it to MI. I think I need to revisit that tune to see if it doesn't want some more high load timing. This one (1500 in sig) needs thinned down some more though at high load/low RPM, the air is a bit thicker now that I've left Colorado and I'm hitting spots on the map I couldn't before.
