It started happening to me yesterday after I turned up my boost to 18psi from 12. I have Apexi AVC-R and Apexi Neo AFC. I've run 18psi before without any problems, for the past month i was running only 12psi.
So here's the problem (this is right after I turned up the boost to 18psi). When I accelarate normally not WOT and not in boost the car acts normal, no problems. However every time I step on it a bit and the boost starts to build, 0psi and up, my car stutters. The RPM is at about 3000. The boost builds up to full but the rpm stays at about 3000, this is when the car stutters, shakes for a bit and then rpm seams to goes up past 3000. This happens in any gear as soon as I step on it and boost starts to build.
I thought this was my fuel pump dying on me because the car acted exactly the same as my brother's SR20det 180sx before his fuel pump died on him. So i replaced the fuel pump today, got the walbro 255, this however didn't solve my problem. What should I look for next? Thanks in advance for any help.

 

so there is no problem with boost? It is hitting the 18psi? No fluctuation or spikes?

 

get rid of that afc and get flashed and run 22 pounds all day long....

 

boost builds fine to 12/18psi.

 

Start with easy things Change plugs- Boost leak test....Things like that. I recomend changing plugs. The car may run real rich at WOT and 12psi, could have fouled them.

-Em

 

I think my clutch is starting to slip, that is why this is happening. When I step on it the rpm sits at about 3000 and the car shakes a bit and then the rpm goes up and the shaking stops. What's the best way to tell if a clutch is slipping or beginning to slip (4th gear, low speed and then step on it)?

 

Yes you would notice the RPMs increasing with out the vehicle speed increasing. Do you have a wideband? If so what are your Air/fuels when this happened. What was the temperature outside when this happened? What are your mods? Etc.

Blake.

 

you can also do a low speed 5th gear pull.