Help! Cars Overboosting

[Benjamin_John93]

Finally got myself a 1996 R33 GTST after owning a few n/a's.

 

Car is stock except for front mount intercooler and boost tee(currently wound all the way down).

3" exhaust from turbo back, cat has been gutted.

 

But im having issues with boost. I only want to run 7-10 psi max but for some reason the boost will just continue to climb untill over 15psi then starts to cut out. I have tried using the stock boost controller but makes no difference.

 

Car had a boost leak which i thought was the problem but i did a boost leak test and fixed the leak, problem still exists.

 

I decided to check out the wastegate actuator but seems to open perfectly fine(not hitting dump).

 

On inspection of the turbo i noticed that there was no compressor outlet where a hose should run from it, to the boost controller, then into the wastegate actuator shouldnt it? Instead my car has a T piece from a hose that goes from the manifold to the charcoal canister?

 

Dont know much about turbo cars as this is my first and really dont understand why its overboosting so much?

 

[Benjamin_John93]

[Griffin]

Is the knob on the bleed valve wound in all the way?

[Benjamin_John93]

The boost tee? Its wound all the way down but backed off a little

[Griffin]

Sorry didn't see that it was. Is there a check valve on charcoal cannister?  Check the t piece to see if it's not restricted.

[admS15]

All the way down is full boost. Turn it anti clockwise a couple of turns and check boost again.

[GTSBoy]

And failing that.....the boost signal must be from the compressor housing, or some point on the turbo-intercooler-plenum pipework.  Anywhere else is stupidly wrong.

[Benjamin_John93]

All the way down is full boost. Turn it anti clockwise a couple of turns and check boost again.

It is turned all the way anti clockwise and back off ever so sightly. But i have the same issue even if i connect it to the stock boost controller aswell.

[Benjamin_John93]

And failing that.....the boost signal must be from the compressor housing, or some point on the turbo-intercooler-plenum pipework.  Anywhere else is stupidly wrong.

There is nowhere on my turbos compressor housing to connect the hose to like there should be, and nothing on the intercooler piping either.

Could the issue be that the hose goes from manifold to boost tee then wastegate?

[admS15]

There should be a nipple on the intercooler pipe that goes to the throttle body. That should be the boost source. Doesn't sound like yours is like this.

Remove the boost controller and run the line direct from your boost source to wastegate actuator and see if you get low boost.

[admS15]

Standard turbo does not have a boost source fitting on housing.

[Benjamin_John93]

There should be a nipple on the intercooler pipe that goes to the throttle body. That should be the boost source. Doesn't sound like yours is like this.

Remove the boost controller and run the line direct from your boost source to wastegate actuator and see if you get low boost.

Cant find any hoses on the intercooler piping that run to throttle body, there is one hose that runs from throttle body to charcoal canister?

[Benjamin_John93]

This is the wastegate on the car, after some googling looks to be an r34 one?


This one is a spare i have in the garage which was ment to be off an r33. (has asn79 written on it )

[GTSBoy]

Look.  The actuator doesn't matter a shit.  They're both 5 psi items.  What matters is that your boost source is coming from somewhere wrong.  The fact that there is no nipple to connect the boost control to on the intercooler pipework IS THE PROBLEM.  Trace the connection back to where it comes from.  if you cannot see/prove that it is 100% from upstream the throttle, with no solenoid valves or check valves or anything else in the way, then fix it.  This will mean PUTTING A NIPPLE ONTO THE PIPEWORK.  Which would be 100% what the doofus who installed it all should have done, and apparently didn't.

[Benjamin_John93]

Look.  The actuator doesn't matter a shit.  They're both 5 psi items.  What matters is that your boost source is coming from somewhere wrong.  The fact that there is no nipple to connect the boost control to on the intercooler pipework IS THE PROBLEM.  Trace the connection back to where it comes from.  if you cannot see/prove that it is 100% from upstream the throttle, with no solenoid valves or check valves or anything else in the way, then fix it.  This will mean PUTTING A NIPPLE ONTO THE PIPEWORK.  Which would be 100% what the doofus who installed it all should have done, and apparently didn't.

Okay thanks heaps mate I will tap a fitting into the pipework and run it straight to the actuator for now, ill be sure to let you know how it goes.

Thanks again for the help, really appreciate it

[Griffin]

 See the shiny pipe your hand is on in first pic ? The pipe that replaced has the fitting on .

[Benjamin_John93]

Thanks for the help everyone, i tapped a new fitting into the intercooler piping as suggested and boost is holding perfectly, no more overboosting! [emoji4]

[Benjamin_John93]

So turns out that not only was the boost signal coming from manifold the problem but also both my factory boost solenoid and boost tee are faulty.

I ran the hose straight from the intercooler to wastegate and get 5psi with no issues, i then wanted more boost so i connected the hose from intercooler to stock boost solenoid(the top nipple) and a hose from wastegate to the solenoid(bottom nipple) and thr car ran like shit and then died on me about 200m down the road.(and yes the solenoid was plugged in)

So now im running a 10psi wastegate from an r32 which seemed to be working perfectly the first time i drove it, went to drive it again later that night and as i was slowing down for lights it died on me and started running like shit (im assuming it R&R).

So im wondering if i keep the 10psi actuator on is the car gonna keep going into r&r until i get an aftermarket ecu + tune?

And is my boost solenoid had it or am i plumbing it up wrong?

[GTSBoy]

R&R won't cause the car to stall off boost.  You have left a big leak somewhere in your pipework, or some similar mistake.  A 10 psi actuator will not cause you any trouble, it will just cause the full load mixtures to be very rich, and the car to be slower than it should at that boost (due to the other half of R&R).

[KiwiRS4T]

2 hours ago, Benjamin_John93 said:

And is my boost solenoid had it or am i plumbing it up wrong?

You are plumbing it wrong. You need a plain T (or maybe your boost T is OK after all).

Boost signal goes from intercooler pipe to T. Another line goes from T to actuator. Third line goes from T to solenoid. The other solenoid pipe goes to bov return pipe (or leave it open to atmosphere until you can sort out a nipple). From stock there is a restrictor somewhere (maybe on the boost signal pipe?) but even without that you should have better boost control.