I was messing with intake snorkel on my ‘04 G35 which doesn’t fit any more because of installed Koyo radiator for 350Z which have filling neck on the right (driver) side. I was mostly concerned about coolant and intake temperatures so I started paying more attention to Cipher logs when I noticed this air flow jump during gear shifting:


Search for “gm/s” on this site (not an easy thing to do) showed similar rush of air in this post Varis/Titek Duct Performance Gains?


What would cause air flow to jump from ~170 to ~210 gm/s (~4.7V) during gear shifting, while at WOT I rarely see MAF more than 180 gm/s?

Thanks

 

I would say it's because the throttle-body is closing when your take your foot off the accelerator to make the shift.

 

So re-opened flap on TB increased vacuum by ~20% at WOT – interesting, why only on some shifts and not others?

Just curious, I am NA and still far from 5V max.

 

can you post cipher's log file.?

 

Sure, here is CSV file for the graph above.

 

i tried to convert gm/s to volts, i just got confused..

In those dips, it goes pretty much rich (11.xx). that's probably when you shift gears and go WOT on the next gear.

 

MaXmood, MAF sensor Volts are in column next to MAF gm/s column.
Yes, AFR dips are at throttle lift – normal.