[VARam1500]

Unmetered air the the problem. Vacuum leak is the difference between metered air and actual, used-for-combustion air. I think your idea is a good one in theory, but to find a way to measure the difference between what the ecu sees and actual is a tough nut to crack. Not to sound like a smart answer, but if it could be done in a practical manner Mr. Bosch would have loved to know how. It's a valuable piece of information that would allow the ecu to figure air/fuel ratio with highest precison.

I'm sure there's good insight from Mr.'s Anders, Darling, and others on the subject. I hope they chime in!

--Case...