07 new body style boost spike during shifts

[spygst]

ok got a 07 new body style rcsb rear mount turbo,44mm wastegate and with a 4 psi spring it spikes to 7-8 and with a 10pi spring it spikes to 12-13 when it shifts 1-2 an 2-3 any ideas theside of the wastegate is ooked up to a pressure source

[SLO TRUCK]

Gonna need more infor than that. Turbo size, Engine size, where is your WG getting its boost reference?

[2boosted]

maybe too big of a turbo for your application !

do you have a Blowoff valve installed? sometimes that helps the creeps !

[farmtruc]

where is wastegate pressure being referenced at? needs to be at the intake manifold.

[spygst]

ok lets see it a 4.8 v8
comp 6767, 81 ar p trim wheel, triple ceramic ball bearing, and the wastegate pressure source is hooked up to the turbo compressor housing,and yes it does have bov.

[farmtruc]

the wastegate vac line needs to go to the intake manifold, for more consistent pressure.

[spygst]

ill try it gonna need lots of vacumm hose! do u think that with a electronic boost controller it will stabilize some?

[George C]

i run my wg reference off the turbo and have always had rock solid boost, this being on my personal setups and customer rides


i know in the 900 trucks the pcm goes to neg timing between shifts unless it was tuned out. when you retard timing that much it will spool a turbo more, can you log truck and see if this is occuring?

[farmtruc]

it's different on a rear mount.

[spygst]

i have tq management removed so it doesnt drop timing during shifts.