Hello Everyone....
Ok, quick summary, I have a 94 stock fd with a newly added HKS DP and RB dual tip catback.
I was boosting 11.5/8/10 or so, so I opted for an electronic boost controller, the Greddy Profec Type-S.

Installed here perfectly, and have been able to successfully dial boost down to a consistent 10psi.

However, this controller definitely is not intended for a sequential set up.

My new pattern is 10-6-10 across 2nd, 3rd and 4th gears.

To try and help, I replaced the check valve to the pressure chamber and some vacuum lines. No help.

Just to see if my car hadn't "changed", I unhooked it and reassembled the stock set up, sure enough, back to the 11.5-8-10 pattern.

So, I'm concluding that it is just the way it will be with this controller!

I've had a thread or 2 on this, and I have heard from several people with Type B I's that also have this issue.

I'd love to hear from someone that had this and found a way to fix it, but to be honest, it isn't that big of a deal...i'm just really happy to know that it isn't something else in the system acting up.

Safe travels out there this weekend,

Eric

 

Had this problem, and only thing that helped it was to install a larger pill in the PC line. Well, I installed a needle valve.... Anyhow, opening up the restriction in the PC line helped, but did come with a bit of loss of boost and response on the primary.

 

can this be done in a 94 without pills?
am i playing with fire by messing with this line?

 

If you got the restrictor built into the nipple you'd have to drill it out first.
As to playing with fire..., well, you're driving a RX-7...
But seriously, if you can find a needlevalve that only has a relatively small passage you will have a much better resolution when adjusting the precontrol. I found one at ACE hardware that works quite well.

You can just start out with the valve mostly closed and keep opening it further until you have your transition dialed in. Don't close it all the way at the start though, or you get no pre-spool at all, which would prevent the second turbo from ever producing the pressure needed to open the... (I forget the name; the door that seperates the primary and secondary in the y-pipe). You would not get any secondary boost.

You might also want to keep the profec turned off or adjusted to very low boost (this would probably be better in the end), when you start adjusting the PC. That way, if you are getting a 2 or 3 PSI spike, it's not way above max boost levels. Get the transition dialed in, than start upping the boost again until you get to your desired level. You might have to re-adjust the transition as you increase the boost, so go in small steps.

It takes some time to get it just right, but it certainly is worth it. Dialing out that deep dip during transition makes the car so much nicer.

 

perhaps divine intervention, or the cooler temps, or well...i have no idea why but i took her out for a spin today....
almost a perfect 10-8-10 (maybe 10-7.5-10) with the profec hooked up and the gain in the same position as before (cranked) and the low boost also in the same spot (~20%).
it felt amazing, and it is so nice not to have to worry about hitting 11-12psi on an otherwise stock car.
looks like there will be no need to tinker with the pre-spool which is a good thing!

happy driving out there,
eric

 

Sorry for bringing this back from the dead, but could you post details of how you have/had this hooked up?