Quote:
Originally Posted by runyonwc
Geoff did show me another run from a stock ZL1, not sure if auto or manual, and it made like 468 or 470 rwhp. Maybe the dyno reads a little low? Still doesnt make sense why it is so rich...
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I've seen one other dyno sheet with an extremely rich AFR like yours. Check out post number #9 in the Official LSA Dyno Thread in the sticky section. That car is an A6 running just a Roto-Fab on the stock tune.
As ZO6 Bryan pointed out, the stock tune will start to richen things up above 5000 rpm. The cat over temp protection will start to kick in when the cats reach certain threshold temps. The ECU can command an AFR as low as 10.5 when those temps are reached. Of course what's commanded and actual AFR don't necessarily match.
It's possible your cats where at those threshold temps during the pulls and hence the reason you have such a rich AFR. Of course this is just a guess on my part.