80mm airflow sensor unit with "67K" decal
Sorry to resurrect this old thread, but I have a related question.
In the "Volkswagen Water-cooled Front-drive Performance Handbook" by Greg Raven (published in 1986), the author mentioned two CIS airflow sensors with 80mm plates, one with a thick rim and a "67K" decal, and another with a thin rim. The thick rim unit has a steeper air funnel, therefore it causes the plate to rise higher than the thin rim version for a given amount of air flow, leading to a richer fuel/air mixture.
I have a 1980 Audi 4000 (came with a 1.6 liter engine and K-lambda). It had a 60mm air flow sensor, but was upgraded to the 80mm "67K" unit some 26 years ago, and mated to the original fuel distributor. The engine was also upgraded to a 2.0 liter.
So, I am seeking more info about this 67K air flow sensor. What year and model of VW/Audi was it found in as stock equipment, and any other pertinent data. Does anyone have knowledge about this particular unit?
Also, since my 4000 has oxygen sensor, catalytic converter and frequency valve that regulates the fuel/air mixture, my guess is that the air flow sensor funnel profile is less relevant in the actual mixture. What do you think?
Lastly, is the original fuel distributor now a performance bottleneck, given the larger air flow sensor and larger engine? Does it make any sense to change the fuel distributor too, and if so, to what version? Keep in mind that I still need to pass the bi-annual California smog check which tests tailpipe emissions.