Have a quick question on which wire to tap on the ECM for my Dynotune A/F gauge. Wondering if it would matter if I hooked it to pin 56 (rear o2) on my 96 Max rather then 50 or 51 (right or left front o2). The reason I ask is because hooking it to 56 would essentially read both banks as opposed to reading either bank 1 or 2 (if it matters in terms of reading which bank is lean or rich). Let me know what you guys think. Thanks

 

bump for a friendly member

 

The rear heated O2 sensor will not give you correct afr readings, since the catalytic converter uses some of the oxygen in the exhaust to do its thing. You will get false rich readings. The rear O2 sensor is only used for monitoring the cat.

By the way, don't expect to be able to do any sort of tuning with the oem narrow band O2 sensors. An EGT gauge is more useful in that regard.

 

Exactly. Either go EGT or get a true W/B 02 sensor. That is as accurate as you can get.