foxbat

AFR is dipping to 10s & even 9s at 1400 RPM, 100% TPS!
Also, load values seem oddly high at the same RPM (around 140) at the same RPM before going to normal reading & normal AFR after 1500RPM. I don't suspect a boost leak since both AFR & load look normal for the rest of the RPM range & go in parallel to both boost level & fuel map.
Fuel map values at 1400 RPM is around 14.7
I suspected a MAF sensor issue & swapped MAF but it didn't solve the issue.

It seems like an closed loop/open loop transition issue.

The car is an Evo 7, 9055 v7 rom
I'd appreciate your suggestions

wreckleford

iTrader: (2)

Vent to atmosphere BOV opening?

I don't think many people have been at 100% tps at 1500 rpm though.

foxbat

No, it's the black plastic stock BOV, could it be a BOV related issue?
True, about the 1400 @ 100% TPS, I was doing that during 3rd gear WOTs tuning the car, my concern is that such issue might affect other areas of the fuel tune or CL to OL transition.

robbyredneck

iTrader: (3)

is it only the moment after you go wot? asynch maybe

foxbat

Yes, exactly! Can you elobrate further about asynch?

mrfred

iTrader: (50)

100% tps at 1400 rpm is definitely an unusual combo. could be caused by many things. i had a rich afr issue on spool that turned out to be due to the stock dv blowing open.

kaj

iTrader: (60)

definitely losing air after the MAF. so at least that helps narrow it down. the DV could be open if defective, but you aren't making any boost yet, really.
and a boost leak test showed no leaks??

mrfred

iTrader: (50)

the plastic valve dvs leak at pretty low boost, maybe not quite as low as his likely boost level during the rich afr, but my issue was similar. my dv would hold 27 psi during a boost leak test, and yet it caused a significant rich dip during spool on a 26 psi tune. and that was with recirc.

foxbat - this issue and other experiences always make me favor looking for potential mechanical issues before going after the tune.