Hey everyone, couldnt find anything that relates to my problem exactly.
I have an '89 s13 with ca18det and apexi avcr all set up
My problem is I only ever get about 0.5 or 0.6 kg/cm2 (i have it set 0.7 wich is 10psi) at about 3500rpm and as the revs go higher i lose boost down to like .45.
I want it to boosting to .7 or .8 all the way through the rev range or as close as i can get to that.
I have a new fmic and pipes so no leaks there, i took the vacuum hose off the actuator and went for a steady drive just to see if my turbo boosts up over .7 and it does. Im thinking it might be a problem with the actuator or the boost control part that has the hoses going into it? Idk does anyone have any input?
I tried increasing the duty/gain but doesnt change anying i even put it up to the max which is like 80% or something

Does anyone know of someone who can help me? I really need to figure this out!

Sounds like a vacuum line is loose. Check the hose that is attached to the air filter tube, which happens to be right after the MAF. That could be loose. Or maybe your connections to the AVCR are loose. The problem with boosting high is that sometimes things come loose because it wasn't clamped tight enough for high boost situations, but it was fine for low boost. I had a problem of not being able to boost at all and getting bad stumbles. Turned out it was my brake booster was unplugged because my tube had popped off from it. Braking also was a b**** to do in order to stop the car!

Thanks, ill check it out

The two hose outlets on the intake pipe after the afm are blocked off and the hose clamp on the i take to the turbo was loose so i tightened it but i didnt think that would have much affect on boost levels because its on the inlet side, but went over and tightened all the other clamps too and i can make it to 0.74 kg/cm2 for like a split second then it drops back down to 0.65 and just steadily lowers from there
Also cleaned my aac valve and noticed the o-ring on the idle adjustment screw is basically pressed flat and air leaks past it so could be that too? Not sure

If it will make over .7 w/the line disconnected from the wastegate, then it's not an issue with the actuator. Either the vac lines aren't routed correctly, or you're programming the AVCR incorrectly.

Sounds like you have fixed the vacuum (for the most part). Your remaining problem has to do with the AVCR programmed incorrectly as Float has said. Don't ask me how to program it though, as I have a Profec B I, which is about as simple as a EBC can get (three knobs, one is gain, and the other two are low boost and high boost profiles). My friend has an RX7 with AVCR and I couldn't figure that out for the life of me, so I decided not to touch it.

Yeah it is a real bast*rd
I have somewhat figured it out and ill write my process for anyone interested.
First i got a manual, for the Apexi AVC type R which is what i have duhh..

I initialized (reset settings) the avcr. From there i re-entered my vehicle details etc, disengaged self learn for the gears and adjusted "feedback speed" slightly higher for 2nd and 3rd gear (not sure what that does but in the manual it tells me adjusting this reduces boost drop) after that i switched the settings to off (not setting A or setting B) in the main menu. Then i did a test run to see what "actual boost" is, i got about .67 and it drops as the revs go up, so i set my "desired boost" (in the boost/duty setting menu) to 0.85kg/cm2 and duty cyle to 30%.
then i did another test run and got pretty much the same result however my boost stayed around 0.67 from 3750 to probably about 5000rpm.
So from that I raised my "feedback speed" some more and increased valve "duty" to 40%. I then kept doing test runs and in reasing "duty cycle" and "feedback speed" until i got to where i am now which is 0.75kg/cm2 and 50% duty with increased feedback speed in 2nd and 3rd and less of an increase in 1st and 4th.
Its still not 0.85 but im assuming with more playing around i think i can get pretty close.
It explains all this in the manual but its in a very roundabout way and hard to understand i had to read it about 4 times.

The avcr if set up properly should allow you to see injector duty aswell mine says im maxing out my injectors at like .65 so i dont think its right.. idk just thought id add that in there

Turns out that my solenoid valve was hooked up wrong, after sorting that out,i restarted it and adjusted everything as i said before only this time instead of increasing duty and having it increase boost, more duty = less boost. Had no need to adjust feedback but still left self learn in gear switched off