MAF Lb/Min question

[AkWhtBst]

Looking over my data logs from the 4th of July at the track I am seeing a spot in the data log at 6600-6800 rpm's in 3rd gear where the maf lb/min slows its increase way down compared to the rest of the data log. The car seems like its missing some more power and I wonder if this is an indication of that.

I'll provide the data log and the tune file I was running.

Mods on the car are: 14GT A6, 4C converter, lth, offroad xpipe, ported boss intake, 11mm 290 degree duration exhaust cams and stock intake cams, bmr rear suspension, viking rear shocks, one piece drive shaft, front sway bar delete, transbrake and wotbox set at 3200.

This pass was a 11.32 at 120 mph.

Thanks guys.

Tim

[AkWhtBst]

Anybody?

It seem really weird that the maf lb/min increases at a fast rate until 6600 to almost 6900, sometimes 7000. Has anyone dealt with this? Is this a sign of something in the tune not being quite correct?

Thanks

[MarkTucker]

It doesn't appear to be any issue. The MAF lb/min in your log seems to be pretty normal.

[Blueprint]

Have you tried messing with the cam timing?

Try opening the exhaust valve sooner. This will help use the cylinder pressure to remove the exhaust gases, instead of the piston doing all the work. There is point where all of the energy has been transferred to the crank, after that point its best to begin to open the valve so you can use the highest cylinder pressure to help push out the spent combustion, the further the pistons goes down, the more you are losing that aid. Just not too soon, it will take some testing (dyno would be best).

This is just an idea. I do also believe I saw minor knock. I would mess with spark too.

[AkWhtBst]

The car seems to get a little positive knock if I get on the gas too fast while using the transbrake. That makes sense and I will give that a try. I won't be able to get back on the dyno anytime soon but I am going to the track this Friday and will see if there are noticible changes by doing so.

Thanks for you guys advice.

Tim

[murfie]

Comparing your commanded and actual lambda, it looks to me that your maf curve is slightly off in the higher flows. you are about 3-4% rich from period 120 to 110. Your Maf changes its rate of climb right as your actual lambda crosses your commanded lambda and starts to go lean. This is in every gear. I would multiply 123 to 107 period by .98 and see how it goes. It will smooth out the maf's rate of climb.

[AkWhtBst]

Comparing your commanded and actual lambda, it looks to me that your maf curve is slightly off in the higher flows. you are about 3-4% rich from period 120 to 110. Your Maf changes its rate of climb right as your actual lambda crosses your commanded lambda and starts to go lean. This is in every gear. I would multiply 123 to 107 period by .98 and see how it goes. It will smooth out the maf's rate of climb.

I will give that a shot. Thanks!

Tim