Scantool or Hammer wizards: Oxygen sensor reading

rbogh901 · 02-06-2013, 10:59 AM

Educate us please.

How can one tell if you are running a correct Air Fuel mixture from the oxygen sensor readings? And if it is not within a correct range, how can you tell if it is lean or rich?

porterdog · 05:01 AM

If you're running the stock oxygen sensor you're not going to get very good information from it. The older style (narrow band) units have a very steep output curve:

Additionally, they were never intended as a tuning tool- rather they were to enable the ECU to "dither about stoich" to keep the catalytic converter operating as intended.

If you're observing the behavior of such a sensor and want to know if it's working, look for values which oscillate around ~0.5V (assuming the reported value is voltage; if it's processed in some way.... dunno!)

rbogh901 · 02-07-2013, 07:51 AM

I see what you mean. Is the solution to clip a wideband oxygen sensor to the exhaust?

porterdog · 02-08-2013, 05:24 AM

Welll... kinda. What you really should have is either a) an additional bung welded in for the wideband unit (and corresponding gauge in the cockpit) or b) a WB setup with NB emulating output. These units (pretty sure I've seen this feature) will feed WB info to your cockpit gauge and simulated NB output to your ECU.

Speed costs money

rbogh901 · 02-10-2013, 02:17 PM

Quote:

Originally Posted by porterdog

Welll... kinda. What you really should have is either a) an additional bung welded in for the wideband unit (and corresponding gauge in the cockpit) or b) a WB setup with NB emulating output. These units (pretty sure I've seen this feature) will feed WB info to your cockpit gauge and simulated NB output to your ECU.

Thanks porterdog. I wasn't aware of those but they do sound spendy. Therefore, I think the option of an exhaust tip sniffer makes more sense for me, plus I can use it on my other cars. With a cat bypass this should work, correct?

porterdog · 02-11-2013, 05:00 AM

What I've read (no direct experience) is that going in from the tailpipe will give you erroneous readings because at some point during the exhaust cycle air can be pulled *into* the system. In general I think the further upstream you go the better off you are.