I have a h22 in a 93 h/b with a gsr ecu. I'm using a vafc to control the vtec. When it starts to switch to vtec it spits and sputters. The more i drive the car it spits and sputters a lot not just during vtec. I unplugged the vafc and it ran real smooth, but no vtec because its only ran through the vafc. I throwing two codes 21 (vtec) and 41 (heated o2)

 

First, you NEED to hook the vafc up correctly. The vtec wire from the ecu has to be run into the vafc, or else the computer WILL throw a code. You cant just leave it hang. Also when installing the vafc, certain wires from the vafc need to be spliced into the same wire in the harness near the ecu. These need to have space between them, one closer to the ecu than the other one. Make sure thats been done correctly.

Since your computer detects a problem with the vtec, more than likely its not providing enough fuel. More than likely thats the cause of your sputtering.

 

a gsr ecu runs leaner on a h22 but that gives it better topend.
from dynos i've seen.

what injectors are you using?