GTO/3000GT Loss of boost

[rossy boy]

Recently replaced the turbo induction hoses on my 3000GT and since have noticed a severe lack of response in boost. The boost gauge flips up even faster than normal (stock gauge at the mo) but with no actual pulling power. The problem seems obvious as I can hear air being sucked in from under the bonnet somewhere. The new pipes (SAMCO) have bigger connections for the vaccum hoses but the front turbo never had the small hose connecting to it like the rear one did, so I'm left with a massive hole in the front pipe which is where I think the air is being pushed out of. When I replaced the pipes there wasn't a hose connected to the old induction hose-just the smaller protruding pipe. Can anyone tell me where this hose is meant to come from cos I can't see any unconnected hoses anywhere.

Ps all hoses are connected securely.

 

[turbonutter69]

Block the hole and try that.

 

[rossy boy]

Yeah that was my other option but wasn't sure if it would cause any other problems

cheers

 

[Country Bumpkin]

That hose is only used on Mk1 GTO's, it goes to the charcoal filter cannister under the fuse box, which is part of the fuel tank breather system. The hole you have won't be pushing air out as it is an induction pipe, it will be sucking un-metered air in. Air comes in via the filter, it is measured at the MAF and the ECU takes this as a reference, any air after that is not seen by the ECU.
As t/n says, you need to block that hole, the Samco pipe is a universal fit for Mk1 & 2 etc.
The small pipe on the rear hose is a boost reference pipe. It has a reducer inside it to control/limit air and prevent overboost. If you have replaced that smaller pipe with another one, you need to re-fit the original small pipe which runs to the Y-pipe, or at the very least use the part with the reducer in it and use a pipe reducer to link that pipe to a larger one which fits the rear Samco hose outlet.

 

[rossy boy]

yeah the boost reference pipe is the same one I didn,t replace it.

Thanks Lads

 

[indiaman]

It is obvious that you have a leak on the pressure side, attach a simple water gauge along the pressure pipe and you will spot the leak