I understand the duty cycle theory, been through it on my 300E. But the 1986 2.3 engine only posts the voltages in the factory manual. Is that the only way to determine what is going on or is there a corresponding duty cycle number as well? One thing that has not been discussed at all is how altitude correction devices are employed by M-B. (ie how it effects EHA numbers) The theory part of the factory manual hasn't said HOW it makes its corrections. And precious little on how to test for it. I have read your articles in depth and appreciate your input on the board....Scott