| saying to light: Take a look at this ZEM fuelmap trace:
 You are seeing a map trace at 15psi, sea-level in green. This is showing you what values in the fuel map are being used for this pull to redline. When the car is breathing less air, as is the case when you are running 15psi at mile-high altitudes, the engine is under lesser load and this will be reflected in the map trace. It would be the same as running around 12.5psi at sealevel. At this airflow level, you are going to be using map values at least two columns to the left of what you see used in the map trace above. If you take a close look at the enrichment values in the map, you will see that by 3200RPM, this car is using an enrichment value of 24%. At 12.5psi, that is going to be around 23%. If you continue further down the map, you will see that the differences between what values are used at 15psi vs. ~12.5psi (2-3 columns to the left) you will see the the spread increases to 14% at around 5900RPM. 14% less fuel delivery is going to account for about 1.4 points of A/F difference. So when you would normally see an A/F mixture of around 11.5:1, at this lower absolute pressure, it is going to bring the A/F up somewhere around 12.5-13:1. We all know that JWT's programs run excessively rich, which is the reason you see that chenc's A/F is around 12.2 or so by redline. There was nothing wrong with that A/F sniffer box - it has everything to do with the difference in relative atmospheric air and how it affects the operation of the ECU. Now one may consider that this would be a problem with the ECU, but it isn't. At these lower airflow levels, although the boost gauge tells you it is running at 15psi, you aren't flowing as much air as a car at sealevel running the same boost - because of this, the mixture appears leaner than it should, but it is actually spot-on. IF you see a stage3 TT at 15psi running an airfuel that appears to be too lean, please consider what I have shown you here. With respect to the numbers with SAE correction applied to them at your altitude, I'm working on that for you guys so sit tight.
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