My boost pattern from 40 mph 3rd gear x to the floor pull was
12 psi ...then a drop
6 psi ....then a slight rise to
8 psi .... then boost started to drop off as i continued to acclerate.......
I did notice from a stop if i acclerated very hard or launched the car will boost up 8 psi and then start dropping.....
If i am cruising in 3rd gear or 4 th gear and i punch it at any speed i will get the above boost pattern.......which is 12 6 8 and then boost drop off....
HEPL HELP HELP.......
i think it is my 2nd turbo but where should i start??????
peace
sean

 

Did you do anything to the car?

Like Vaccum hoses..? Also check the charge relief value...looks like the BOV valve but farther back.

Also check the y-pipe rubber coupler... can leak boost if cracked.

Check the selenoids... and by the black vaccum tank for poped
off hose... May the boost be with you. jc.

 

what is your boost pattern:
BELOW 4500rpm
AT 4500rpm
ABOVE 4500rpm

Reason is because if your boosting up to 12psi on the first turbo, it WILL drop to about 8psi at 4500rpm during the transition to the 2nd turbo. If you have a faulty turbo control system, then it will stay at 8psi and slowly start to bleed off to 6psi and below.

 

i have the SAME problem....FLYBYE....where do u find that *FAULTY TURBO CONTROL SYSTEM*??????

 

could be clogged preCat or Cat (if you have a DP)

 

I have always had this problem with my car...i thought it was a clogged cat and precat so i installed a mid pipe and dp but still no changein boost pattern....
i think i am just gonna pull the hole turbo and go single..i got all the parts necessary........
Greddy cast manifold,
greddy tdo7-25g
Type r wastegate..
what you guys think?????
should i go single with the above set up or go non sequential ????

 

Could be, but he already got rid of them.

I seriously hope streetpower is running an aftermarket ECu with the MP. Anyways...

The most COMMON cause of this problem is a simple hose popping off. You see, the turbo control actuator that is used to open the flap to allow more exhaust gases to get to the 2nd turbo uses vacuum AND boost to open. I bet you are wondering "Where the hell does it get vacuum from when the entire system is being pressurized by boost?" That's a good question

Look behind the power steering pump. You will see a black tank. THAT is your vacuum tank designed to hold vacuum. Check to make sure it has a tight connection and the nipple isn't broken off. The nipple on my tank was broken off, which was causing MY secondary boost problem a few years back.

You may also want to buy a vacuum/pressure pump to pressure test it. I can't tell you how valuable this little pump has been tome. You can use it to pressure and vacuum test the solenoids, actuators, 1 way valves, hoses, vacuum tank, the pressure tank, and anything else you can think of.

www.mityvac.com


Even if you can't find a loose connection, if you still have some old hosing down there, one of them may be slit not allowing vacuum or pressure to get to where it's supposed to be. Check ALL of yor hoses and connections first.

If you checked all of yours hoses and connections, and pressure tested the tanks (the tank behind the PS pump and the one sitting on top of the engine), then it's time to pressure test the solenoids and actuators, but that's another story

 

ill check it out this weekend when i am installing my intake........
thanks!

 

Yeh i got an XS engineering remaped
yeh i owned a Mityvac vacumn pump
yeh i need to check that tank.....
i will update
peace