I keep on seeing/reading varying reports. My
opinion on the matter is that you can use it for N/A tuning so long as the sensor has been scaled correctly. I have no idea what Shiv's O2 sensor scaling is like in comparison to the given ECUtek scale. It seems that the sensor is more accurate the closer to stoich (14.7) but loses it's consistency further away from that based on pressure and temperatures. Therefore I wouldn't do repeated runs without allowing a cool down period if you're doing OL fueling, this doesn't necessarily mean stopping just don't do WOT constant runs back to back.
To make OL scaling easier, you could set the map to a flat AFR of loads 1 and above - eg all cells 12.5/12.6 etc. This makes it easy to analyse and won't be an issue for a couple of runs that are needed for scaling. Due to the sensor accuracy, you want it as lean as possible
BUT remember if your MAF scaling is already off then you could run leaner than the commanded AFR.
How I've been looking at it just for MAF scaling on an NA car:
- 1st runs with a map of 12.0/12.1 - If you've already got logs, you have an idea whether your scale makes you run lean/rich. Do a few pulls to get good data - I like 3 or 4 pulls from 2.5/3k to reline.
- 2nd runs around 12.5
- 3rd runs - fine tune with as lean as you're happy to go, but reduce timing a little to prevent knock. With the DI capability I personally would go as high as 12.75 but only for a couple of pulls.
That should be enough. If in doubt, always make the MAF scale a touch higher. I'd rather run 0.05 richer than leaner.
If you can visualise the data in graphs etc, you can see if the stock sensor starts to read inconsistently and then discard that data.
Once you can do this, I would seriously look into latency and PI/DI scaling as it's just an evolution of this technique.
Also worth noting on CL MAF scaling, as per @
jamesm's screencast, don't go mental and randomly adjust each point. You want to adjust everything together.