i searched, found this thread: https://www.rx7club.com/showthread.p...ht=boost+surge ...
but this only shows the problem not the fix. ive noticed it since i bought the car. and i was tuned last week by BDC (great tune btw). the symptoms are: under wot in anything above 2nd gear around onset of boost (5-7psi) at near 4500 rpm i hear a woosh-woosh-woosh and the car bucks some then settles out aroun 9-10 psi and power is on strong. it seems to stop around 8 psi and is nonexhistent after that. i mostly notice it when i roll into wot in all gears. BDC thought it may be a boost or vacuum leak but we checked all ic piping. and vacuum lines. everything is fine, but i still notice it. i dont see any more than .75 bar on pfc, and i sustain 9 to just under 10 psi as per a petit boost gauge. i dont want to turn it up until i find what this is. the tune is solid, i know its not that. i see 11.1-11.3 tops at wot. anyone have any idea? it seems to me like a wastegat flutter or something causing the wastegate to open or flutter as boost increases. again, the vacuum lines are all on. my mods are:
2mm atkins seals, mild street port (around 1500k miles) greddy profect b (the good one), 1680 2nds, stock prims, aeromotive fpr, front mount, greddy type s bov, supra pump, power fc, pulleys, cltuch 9.5 lb fly wheel, 3 inch turbo back no cat exhaust, twin intake, non seq., fluidine rad, and a few others.

BDC thought it may be the bov, but i dont hear the sound it makes when opening.

 

Here's alink to how things are supposed to work.

http://robrobinette.com/boost_note.htm

It sounds to me that you feeling the normal transition from the primary to secondary at ~4500 when the transition occurs. A normal boost pattern is 10-11 psi on primary, a small dip to 9 or 9 at transition, and then 10 psi until the revs get high enough that intake and exhaust restrictions cause the boos to taper off.

 

Who is BDC and are they in the Charlotte area. Was your tune done on a dyno and how much HP did you have?

 

well, BDC said it wasnt normal. it does sound like something leaking... that woosh woosh woosh doesnt seem right.

 

bdc is brian cain. he is ou of dfw texas. he flew in to tune and buld a 3 rotor in columbia sc. i thought everyone has heard of BDC.