| OK... I just need some clarification regarding the effects of high altitude on air/fuel ratios and the corresponding effects on the performance of my 300zx. So here is what I understand: 1.) The Mass Air Flow Sensor on a Z32 roughly measures the volume of air moving through it based on a known cross sectional area and the velocity of air moving past it. 2.) The Air Fuel map of a z32 is a table of values using 2d interpolation of theoretical pusewidth (a value determined by the CAS reading and MAF voltage) and engine RPM. 3.) The stoichimetric ratio of air to fuel is ~ 14.7 lbs of air to every lb of fuel. The MAF idea conceptually works fine when assuming the air is always the same density; however, in a high altitude environment, the density is much less. I personally live in Albuquerque, NM (~5000ft above sea level), and from what I have calculated, the volumetric density of air is roughly 86% what it is at sea level (calculated from the change of atmospheric pressure). This means that for every x quantity of air that is measured by the MAF sensor (volume), only 0.86x of O2 is actually ingested into the engine. Questions: So does this technically mean that for the same TP (theoretical pulsewidth) on the Z32 ecu at high altitude I will be running richer than my same setup at lower altitude? Or is there some type of correction factor from the O2 sensors which help "teach" the ecu that, for the same volume of air, there is less 02 actually present and will actually lean out all the maps? Or what else am I overlooking? Additionally, what are the important aspects when tuning for high altitude? Have any of the JWT, Ashspec, Ztuner, etc. ECU users experience different air/fuel ratios than what should be in their maps because of this phenomena?? This is really confusing me, and I would really appreciate any help. Thanks.
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