Do I need to weld in an extra bung for tuning with cats?
Do I need to weld in an extra bung for tuning with cats? I need to get my car re-tuned and this time it has catalytic converters in the x-pipe. I know without cats the tuning shops can stick the sensor up the tailpipe. I can't see this being the case with cats because of the conversion that takes place inside them. Does this mean I need to have an extra bung welded into my long tubes for the wideband to be placed before the cats?
From what I understand it will skew the readings so it is best to have the Wideband closest to the collector as possible. If you don't have the room or just want a simple way to add the wideband you can use one of these..
http://www.summitracing.com/parts/av...H4wxoCX97w_wcB
http://www.summitracing.com/parts/av...H4wxoCX97w_wcB
Depends on just how accurate you think you need your AFR to be measured. I'm not qualified to answer how much the catalytic converter changes the amount of un-burned oxygen in the exhaust stream. But I'm willing to bet it isn't that much.
Another option is to just tune off fuel trims for cruise & idle but you will need a wide band to know what the WOT air fuel ratio is.
Another option is to just tune off fuel trims for cruise & idle but you will need a wide band to know what the WOT air fuel ratio is.
I spoke with a local reputable tuner and he assured me a tail pipe sensor would work just fine. He said high flow cats like mine don't do much at WOT because the gases are moving so quickly.
