Taking control of the boost

[Jason_L]

I did some thinking on the basic results from my rerouting of the WGA (see my "poor mans boost controller" thread). Note that my guage is in bar, not psi, so my psi numbers here are ball park.

What we are seeing in non-stage 1 stock cars when the boost drops to around 5psi is just the WGA doing it's job. duh, it's a 4-5psi waste gate. The 12psi or so we see it run up to in stock is the PCM letting the boost run up before it opens the WGA solenoid - what we have in the PT is an EBC at the #2 solenoid, and it's tuned for midrange punch (like a dual stage boost, but stepping down instead of up).

It would seem the simple way to override the PCM's RPM/Boost/etc maps for controlling the WGA is to just cap of the line from the #2 solenoid to the WGA, and just use another pressure source to feed your MBC/WGA. This would bypass the #2 solenoid and the PCM's control altogether, and let you hold whatever boost you wanted to redline. In my case, w/o a MBC all I had was the base 4-5psi of the WGA I'll be using a larger bleed valve and see what happens

If you prefer to have that boost drop off at higher rpms, but want to raise it to a higher point (say, 12psi) then putting the MBC between the solenoid and the WGA would seem to let you adjust this part of the picture (as others have noticed).. it would seem that setting an MBC here at the same point as the factory peak would remove the boost drop as well. I'm not really sure yet what would theoreticaly happen if you were to crank up the boost point here to higher then stock..

Placing an MBC in front of #2 solenoid would seem to let you run up higher then stock boost, but then the boost drop would still be managed by the pcm. Place an MBC at both points (maybe just a bleed after the solenoid), and I would think you could get full controll - give yourself a 18 peak before the solenoid, and drop to 14 after the solenoid, etc.. pick up some solenoids and rpm switches from an NOS supplier, and you could have all sorts of fun but then an EBC would be easier!

[Jason_L]

Messing around with various simple air bleeds at various points in the pressure lines, I was able to push the boost up (as has as 21 psi, but I yanked that bleed off immediately) and hold a higher boost level longer, etc..

But I've noticed the "flutter" that others have talked about (and I have a bone stock intake, so the factory airbox/silencers do not "hide" this sound). It seems to happen when letting off from partial throttle at around 2500+ rpms.. Seems logical that it would be the surge valve, but why would it be acting differently? . I'm thinking the faster spool (from my experiments, and others CAI systems)is bringing higher pressures earlier in the rpm band, and maybe this is messing with the stock SVA some how?

[flashbk2]

Jason here's a link to how we first hooked up MBC which is what I'm still running total cost around $50.00 . http://www.ptcruiserlinks.com/forum/...oost,C ontrol. It's not without problems ie1188 codes. Presently I'm set to 12 lbs boost as it's available @ about 1/3 throttle in any gear, I may get a spike to 13/14 but it settles to 12 and stays as long as I'm in the throttle. After shifts I'm almost instantly pulling 12 lbs again. Don't know if you'd had the opportunity to read .