Well I went to get my VAFC II tuned and it was a disappointing experience. I baselined at 195.7 on a dynapack. After tuning I was only able to get 204.3 @ 8241rpm. We couldn't figure out why the loss of power. No CEL and A/F ratios were w/in norm with the VAFC and without. We even disconnected the vafc and harness. My tuner said I was losing a good 20hp because of the unknown problem. I'm running 4.57's, Mugen cooling mods w/ hondata gasket, intake/test pipe/exhaust, and denso IK24's gapped at .44. I do have a wiredspeed 02 sim that is propery wired up. I even cut it off for one run, but still had the problem. I also have a yellow box, but that is propery wired up as well. We came to the conclusion it's some sort of electrical problem, but because i'm not throwing a CEL, we couldn't pull codes. HELP!!!!!!!!!!!!!

 

Did you try the MAP whack? I don't want to start using that as a "fix-all" suggestion, but that seemed to help me when I had the following dyno:


Some of my problem in that dyno could've also been attributable to heat soak. Notice how my torque started dropping off after 7K RPMs.

What did your A/F ratios look like?

 

I've been getting this issue for awhile. i've changed O2S, valve adj., comp. test, engine oil change, reset ecu many times.... some are related and some are not but I was hoping... I also do have yellow box but not sure if that's cause..

 

I added the A/F plot. At the time I didn't think about the MAP whack, because I was almost sure it was a potential wiring issue with the 02 sim or yellow box. I guess I'll break out the rubber mallet...

 

Yikes man, what is happening at 6000 rpm?! Did you just recently install the testpipe/o2 simulator? If so, maybe you forgot to reset the ecu?