I did a search both on the net and on the forum and couldnt find anyone with this paticular problem and im not sure where to start diagnosing it, im going to do the whole troubleshooting thing top to bottom this week but in the meantime i was hoping to get some ideas on where to pay extra attention.

heres the backround, the car had an engine fire on the drivers side (lhd) of the bay, replaced EVERYTHING except the block and the twins as the passenger side of the car was untouched by the fire, before the fire boost was perfect 10-8-10

well, got it running and its doing great except im having an issue with the secondary turbo,

1/4th of the time i will loose all boost after the transition, boost is between 8 or 10 then just falls off entirly to 0 or 1 psi when it start to transition.

the rest of the time it will really act up after the transition it will bounce around really hard then settle down and overboost (imagine a tach needle bouncing on the revlimiter thats about what it looks like) almost as if its struggling to regain presssure with the secondary, also makes an odd.. pulsing, hiss while its bouncing.
boost pressure looks like (durring 4th gear freeway pull)
10-8-6-8-9-8-10, then smoothly overboost to 12 before i lift off.

mods are as follows,
apexi intake filters, large SMIC, purplebox ecu, mbc (replaced wastegate restricter pill with bleed valve), downpipe, stock cat, magnaflow weld in muffler, greddy intake elbow.
car is an auto.

any thoughts?

 

I assume after the fire you replaced all the vacuum lines? How about the turbo solenoids and map sensor?

 

yes and yes, however im not using the wastegate solenoid anymore because of the installed bleeder valve. the other one is still being used, every single piece under the intake manifold without exception was replaced, every wire, every solenoid, every vaccume line. used high quality high temp lines, routed according to diagram, had myself and another mechanic tripple check the routing as i dindt want to have to question it later.

 

Seems like the wastegate solenoid still needs to be hooked up even if you replace the pill with a bleeder valve. This solenoid pulses on and off, and the pill or bleeder valve only smoothes out the air pulses.

 

no, i had it set up this way before the fire and had perfect 10-8-10, its something else, not sure what though.

 

Were the replaced Turbo control solenoids new or used? Were they checked for proper operation prior to install?
It sounds likes one of the control solonoids is working intermittent.

 

very used, i did apply 12v and listen for a click, thats about as close to tested as we got. I'm thinking the same thing. its very hit and miss, seems worse when it warms up, last night i left a parking lot while it was still cooler, and accidently boosted to 15

I hate to go non-sequantial on an auto but.. ya.. im thinking i might have to

 

Well I am tired of the heat soaked solenoinds so I am biteing the bullet and going this route so I can maintain the sequential system.

https://www.rx7club.com/group-buy-product-dev-fd-rx-7-269/custom-solenoid-rack-968956/

 

My first experience with solenoid maintenance involved breaking off a bunch of baked hoses. So, I relocated them behind the ABS system.