hi im installing an Air fuel ratio and rpm mapping system. im wondering where in the exhaust system would be the best place to put the sensor to obtain the most accurate reading . i have TA shorty headers for a 83 buick regal with 3" dual exhaust the rest of the way. thanks for reading. Zgibbs89
Anyplace downstream from the collector should be fine but before the CAT (if you have one). On my car there are O2 bungs welded in about 12" behind where the downtube levels off under the car - right aout where your ankles would be if you had a Fred Flintstone mobile.
if at all possible place the sensor in the pipe between 10 and 2 o clock....3 and 9 o clock will still be good but nothing below
as far as the angular placement that what i have read. anything under the 3 o'clock and 9 o'clock allows condensation to collect in the sensor which can cause issues. what is a good air fuel ratio to shoot for when tuning my setup? thanks Zgibbs89
Ive got a similar setup. Shorties w/ 2 1/2" exhaust on an 81 regal. I placed my 02 for the ez-efi about 4-6 inches back from the bend on the down pipe. As far as A/F goes, if your referring to a 455 its going to be hard to know for sure without more info ( particularly cam info ) but mine seems to idle at around 13.0:1 and 12.3-12.5:1 WOT. Engines should be tuned to what they like not necessarily what is considered "optimal" ( ie 14.7:1 ).
