CIS Guru Question

[stlrj]

Originally Posted by Pkaaso

My concern is that the lean condition is coming from the possiblity of the "Air Flow Sensor", or "Metering Plate", or the geomitry inside the part is different from the 78-79 and the 81 that I have. i.e. bigger throats, plates, ratio of plate movement to F.D. plunger/rod movement.

I can only assume that your car is smog legal which means you have a cat and your measurements were taken after the cat...is that right?

Could that be the reason your mixture might appear leaner than you expected?

For purposes of tuning, I was under the impression that mixture readings should always be taken before the cat as stated in the Porsche Spec Book.

[Pkaaso]

Stljr,

My car is a 74' with an 81' block, a 78-79 Euro intake.

No smog problem. I just had a lean condition at higher RPM's. I changed the metering plate to the 80mm and so far seems to have made a differernce for the better.

Paul