Boost drop between gears..?

[Lenno]

hey guys !

I've noticed a problem with my 33 gtst lately, when I floor it in first and hit second I seem to get heeps of lag in second where the boost gauge sits on about 3 to 4 psi, then after a second or so hits up to the 8-9psi setting. I'm using a bleed valve but have never noticed this problem before.

Any ideas people ?, one mate did suggest the wastegate could be sticking a little.

Thanks in advance..

Lenno

[nitemare5]

Did you bypass the standard solenoid when installing the bleed? It sounds like you haven't, because the standard solenoid has a 2 stage boost process, where before 5000rpm (or there abouts) it will cap the boost to around 4-5psi, then after that hit 7 psi (or 8-9psi with exhaust)

[Lenno]

thanks anyway nitemare5.....but i've bypassed the solenoid, never had this problem before. Its only between first and second, every other gear the boost goes straight to 8-9psi..ie no 2 stage like when it was stock.

idea's anyone..... anyone ???

cheers

Lenno

[\\\Wiktor]

Probebly it's just that the engine hasn't the recistence it needs to push the boost up.

It's recistance that makes boost. Thats wy you allways check max boost at 3rd and going up a sligth hill..

W

[GunMetalR33]

Try swapping your bleed with a mates if you can and see if the problem persists. If that does not fix it then I would say that you waste gate might be catching???

other than that I am stumped, cant think of why it would only happen in second. Do you have an auto or manual?

[GunMetalR33]

PS, are you getting an ignition cut in second when experiencing the problem? Your hoses might be loose of your bleed which would make it over boost then your ecu would cut the ignitions therefore limiting the boost?

Long shot :-} ???????

[qikr33]

are you using a turbo xs bleed valve (gated)?my mate had similar prob with his so we put my turbosmart one in and all fixed.....just a stab in the dark but i thought i would ask aaaaiiight

[BHDave]

Heres one from left field.

Have you considered that the rears may be spinning so the drop in revs when you shift to second is dropping the engine below the boost threshold.

I have this problem in spades if not careful as i'm running a high flow turbo on an rb20 that doesn't start makin decent boost until about 4000. With a stock turbo this is unlikely

I've also had a problem in the past of a gated bleed valve not releasing pressure in the line to the actuator and holding open the wastegate, though this was preventing any boost coming on until 6000 or so.

[Lenno]

Thanks for all the ideas guys, the bleed valve i'm using is 2 mths old and is the turbosmart brand, the car is a manual.

i'll try swaping the valve and see what happens.

BHDave you could be on to something... the wheels usually are spinning just before i hit second, but then still spin into second even though the boost lags for a second..i'll have to investigate further.

cheers

Lenno

[BHDave]

You'll find that boost will drop off once the wheels start spinning because you can't maintain load on the engine, so your turbo will be spinning slower to start with and then slows a bit more on gear change.

Out of interest is the bleed a turbosmart single stage with incabin switch? and does the problem only happen in low boost mode? Mine was put together wrong in the factory and i had to fix the bastard.

[Lenno]

bleed vave is under bonnet type. whats got me stuffed is that it will still spin into second pretty hard but still feel laggy and as i said boost slowly swings to about 4 - 5psi then rockets to 8-9, all at about 4000 revs, as revs dont really rise untill boost does..

I'll have a chat with the mechanic and get him to drive it, see what he thinks.

cheers

lenno