Ok, I'm wiriting this for my brother who's having issues with his motor.

His current setup is a 1991 Civic Si with a B18C swap.

MODS
B18C with B16 Trans with Phantom grip
Aem short ram intake
Skunk 2 Stage 2 Tuner cams w/ skunk2 cam gears, springs and retainers
Skunk2 IM with stock throttlebody
DC Sport 4-1 Header
Apexi WS full exhaust
MSD Digital 4 with wires & blaster coil (2 step setup as well)
Tuned by Sav Leone @ Impo Performance ( P73 Ecu )

I think those are all the mods he has. Now here's our problem. We have vtec set to enagage at 5800rpm. When it engages we noticed the car would hold back for a second and then it'll free up. We then tried to rev the motor while sitting still and noticed the car starts to misfire from 5800rpm to about 6200rpm. We tried a stock P30 Ecu and we still have the same issue.

My brother says he hears a clicking sound when he reaches 5800rpm (not WOT)
We first noticed the problem when we went to Atco Raceway. 1st and 2nd gear pulled nice. But while in 3rd gear he said he felt as if the motor bogged/misfired while in vtec.

We checked several things. Speed sensor (if failing it will shut off vtec), ecu, vtec solenoid (also checked the screen), Tps sensor...
Any one know what else we can check? Any input will be greatly appreciated.

FORGOT TO MENTION***
we did a vacuum test, our vacuum reads 20psi but when vtec engages it drops to 10psi... thats where we're stumped

 

get rid of the msd and get a stock distributor. i bet thats your issue.

also, is the oil pan dented?

 

You think so kyden? why's that?

 

The oil pan is fine... actually the header is kinda dented a bit

 

20 psi is above atmospheric pressure so it is not a vacuum. Manifold pressure should drop (vacuum increase) when the vtec engages because more air is being pulled in at the same size throttle opening. It sounds like you aren't getting enough fuel at vtec. Check the A/F ratio, fuel pressure and MAP sensor voltage at idle and when the vtec engages.

 

delsol, We did raise the fuel pressure a ton, we had the laptop connected while revving the car where the misfire occurs but it still did it, but not as much... i'm def going to check thos sensors to see if that might be be the issue, thanks