Originally Posted by
aaronc7
Yeah I've looked at a lot of logs over time. With Cobb becoming very popular in the MQB world, you're starting to see the community a lot more involved in the tuning process, datalogging, etc.
In FI setups I have never really seen an advantage to running lean...marginal power difference. And usually with richer lambda/AFR (within reason of course) you can run more boost/timing etc to easily make up for any sort of power loss you might see by running a lean AFR.
That said I did run into something interesting. Stock tune on this car targets lambda of 1.0 all the time, even at WOT....after a long run it might richen up to .98 or something. On my very first tune revision, pretty much the only thing I did was add fuel to hit mid 12s by redline, and it knocked a bunch. I've heard of "rich knock" on DI and that definitely appeared to be a thing here. But once I turned up the boost, I haven't had any such issues and I'll always favor going on the safer side of things to try and keep the cylinder/piston etc from getting too hot for extended pulls or hard driving.
Without pulling up the log, I think I'm at around -1, maybe -2, ign timing at peak load, and then it just comes up slowly and linearly to redline.
All that said I'm not a pro and don't really have the time or resources to thoroughly test all these things. Just try to take cues from what seems to work the best for a particular car and start there.