How far down the exhaust system can I place the WB sensor? I'm thinking 3 or 4 feet North of the muffler cuz I can easily remove that section of the system and get the bung welded on. Too far?

 

You dont want to be much further than 8" from the collector.

 

Thanks for the advice will do, how come?

 

With a heated sensor you can go further, mine is in the center of my X pipe which is about 10" past the trans crossmember. Works great there. I wouldn't go any further back as the accuracy will drop.

My NB is heated as well, it's about 10" further forward in the system.

 

The idea is to get readings from multiple cylinders. On a V8 configuration thats why you would want it 8-10" from the collector. Death Starr is partially correct with the sensors being heated, but the 2nd reason you want it so close to the collector is the sensor stays hot even at idle and does not have to really on the heater circuit. If the sensor is not up to temp it will not read accurately.

Also, where every you place the sensor make sure it is no lower than the 8-4 o-clock in the exhaust pipe. This is the area where moisture settles and can really foul up a sensor. Another thing to not is do not put the sensor too close to any bends, as the exhaust flows through curves it follows the outside of the bend.

Here is one of the many tuning post I often reflect back on. it touches on a few placement scenarios.
http://www.enginebasics.com/EFI%20Tu...%20tuning.html

 

Thanks for the tips & good articles. Always help to get advice and experiences to help shape your decisions.

 

No problem, Ive been doing a lot of EFI tuning latly on multible types of sytems (DFI, megasquirt). One of the cars ive been tuning is a 1968 vw beetle with a mkr3 vr6 turbo in the back seat, lol. As soon as I get my body panels back from paint ill be retuning my DFI in my 85 trans am.

Let me know if you have anyother questions.