Red on Red WS6
07-20-2007, 03:16 PM
I have a question regarding the use of a wide band and catalytic converters. On my 96 TA I don't have cats and I also have an O2 bung welded in after the headers for my LM1 wide band, this way I can have the most accurate A/F ratio readings. Now my question is I have a couple friends that want to go to the Dyno and have me adjust there A/F ratio but they still have catalytic converters on there car. Do I need to have a O2 bung welded on to tune them or do I just use the A/F reading with the cats on? I am just not sure how the cats affect A/F ratio.
jay_lt4
07-20-2007, 04:12 PM
you should put the wideband o2 close to the front as possible, you dont want to be measuring after the cats
95Blackhawk
07-21-2007, 02:37 AM
Cats will affect 02 readings up to around 4K RPM. After that, a stock cat cannot compensate enough and thus the AFR will read essentially right on.
That's quite interesting. This makes me consider buying a tail pipe O2 sensor clamp for my LM-1. Innovate has instructions on not using the tail pipe clamp for catted cars though. As you say, it is after 4k rpm that the cats have no effect. My a/f read-out from the dyno pull starts at 2200 rpm with a few upward spikes around 3300. After that it's a smooth slope downward.