DanielRicany

On the MAF L98s, has anyone noticed if the AFR changes at WOT from winter to summer?

If it does, how much does it change and is it richer or leaner?

Thanks.

bjankuski

If the MAF is pegged at 254 gr/s then it will get richer in the summer. Less air enters the engine when it is warmer, a rough number is it will get 1% richer for every 10 degree air temperature increase. So 12.5 AFR at 30 degrees may be 12.0 at 70 degrees.

DanielRicany

I just tested it today. Mine was at 12.2-12.9:1 at about 50*F weather. Today it was around 85-90*F, and the AFR dropped down to 11.5:1-12.3:1. I fear it may go richer as we get into the 100*F area...

DanielRicany

Also, the humidity was pretty low today, probably around 40%. If humidity increases while the temp stays the same, that will also make the AFR richer, correct?

Tom400CFI

Both the MAF and the IAT sensor should be able to adjust for density changes in air.

bjankuski

That is correct. Check your data logs at WOT if the MAF is pegged at 254 gr/s then you may have to slightly adjust your PE vs RPM table to lean it out at WOT in the summer. Or buy the blowerworks MAF and retune it with that set-up and the MAF will not peg.

The truth is you could just drive it as is and probably only loss a few HP from perfect.

DanielRicany

I checked my logs from a long time ago and noticed that at around 4500 RPMs it pegs at 254. That is where I noticed it go from low to high 11s down to mid 11s all the way to 6k.

DanielRicany

To be fair, it dynod 344 rwhp at 11.66:1 at 5900 RPMs, so its very close to that now. When its a little colder out it is leaner at the mid to high 12s which I think will make a little more hp. I think this is a safe tune though, as it should be okay for all around weather conditions. I just hope during high humidity it doesn't get too too rich.

bjankuski

It should be fine, it is safe at 11.5 to 1.