QUOTE(r_towle @ Aug 19 2008, 06:31 PM)
I dont understand dead end..
Exhaust is always flowing by via the tailpipe when the car is running...yes???
Will it show lean or rich at the tailpipe?
By what average percentage??? I can do that math.
BTW, this is how the state emmission tests are done
maybe i didn't understand you. i think i see now your planning to bolt a section between the muffler and tip... no?
the o2 is different than the sniffer in operation. to create voltage the one wire o2 along with unburnt fuel relies on heat, the closer the hotter. it can be further downstream if it has "power wires" to self heat.
the sniffer has a pump to draw the sample across the bench to read the hc, co etc... and yes thats how ca. does the test. but it can have false readings if any air makes its way to it by a ex. leak, even huge tip pipes can influence it's readings. the c.o is what could be effected and be slow to respond and could have lean readings.
the closer the better as a rule, but not always practicle. also on a 914 system the exhaust doesn't mix until the muffler so you'd only get a single cylinder reading if very close.