Brake boosting issues

[Babyocho]

Hey everyone I have a Big turbo 50 trim on a 03 PT cruiser using a 04 NGC 3 PCM and stage 1 (stock 04) injectors for srt4/pt gt.I haven't tuned it yet (broke$)just been data-logging to watch everything lately everything reads right where it should accept the stock fuel trims are crazy rich even for a big turbo set up right now. But my issue I've found is my brake boost function is no longer available after the install I'm gonna check my botls and nuts today just to double check physical problems. But when I watch it on the laptop it shows I limit at 2000 rpms with 18 percent fuel trim(stock)and it just holds me there then i leave the line like a hurt dog , is this maybe trq management ?before the install I could almost spool up 10#s of boost off the line with stock turbo understandably it had very little lag but I would be able to rev past 2000 rpms. So any help would be appreciated. Boost junky if you are out there help me please . I'll post and on/off log of an attempt

[B00STJUNKY]

Hey everyone I have a Big turbo 50 trim on a 03 PT cruiser using a 04 NGC 3 PCM and stage 1 (stock 04) injectors for srt4/pt gt.I haven't tuned it yet (broke$)just been data-logging to watch everything lately everything reads right where it should accept the stock fuel trims are crazy rich even for a big turbo set up right now. But my issue I've found is my brake boost function is no longer available after the install I'm gonna check my botls and nuts today just to double check physical problems. But when I watch it on the laptop it shows I limit at 2000 rpms with 18 percent fuel trim(stock)and it just holds me there then i leave the line like a hurt dog , is this maybe trq management ?before the install I could almost spool up 10#s of boost off the line with stock turbo understandably it had very little lag but I would be able to rev past 2000 rpms. So any help would be appreciated. Boost junky if you are out there help me please . I'll post and on/off log of an attempt

Sounds to me like you're simply running into physics... Bigger turbo, more lag. Your stock turbo was so small and responsive that you could build positive pressure at the lower RPM range (where you were up against the torque converter stall speed), and as such, you would make more torque, thus powering through the resistance of the converter's fluid coupling to an even higher RPM, all while building more and more boost as the RPMs climb, and the cycle repeats. Now, with the 50 trim, you can't build much, if any, positive pressure in the manifold to build more torque to overcome the resistance of the torque converter's fluid coupling. Often times, folks that have a tight stall speed in their converter will use nitrous to get up on the turbo sooner and have a stronger launch.

You don't have a "brake boost function" in the PCM. There is torque management that could possibly be limiting things a little (Stall TqMgt Brake on/off Torque), but I highly doubt that's really the issue you're running into.

[spoolboy]

Take some timing out in the area of the map where you get "stuck". Like 10* and watch EGTs.

[Babyocho]

Thanks guys timing helped 👍 and learning the physical limitations of the turbo helped