Huge Overboosting problem

[redlinezak]

Just wondering if anyone else can think of any reasons why i am getting massive overboosting.
My setup is a GT3582R running an external HKS gate all being controlled by an EVC6.
Basically its a drag car only. Car was mapped by JEZ at 1.5 bar a couple of months ago and since then has been to santa pod and did about 6 runs.
Went up Saturday and the first run was fine but the second run it started missing badly in third and 4th.
Cam back to the pits to investigate and my EVC was showing that it had hit 2.4 bar boost.
Checked the hosing etc and went out again and it was exactly the same so i called it a day.

I have not investigated it yet but the obvious culprits will be the external gate and the EVC (and associated hosing) but before i start pulling it apart does any have any other potential causes.

I think the boost was only being limited by it blowing out the spark / misfiring etc.

My best guess is a seized wastegate piston which should be relatively easy to check.
If no that then maybe the boost controller solenoid stuck in open position?

Anything else.

Thanks

Nath

[ANDY black s13]

If the wastegate has a diaphragm I would check him first for splits or perishing (lots of tiny splits at point of flex)
, the valve could be seized, and could test it opens with a pressure feed to the line on the 'gate
if you can get screamer pipe or plumb back pipe out the way to see the valve open,
or remove the gate from the manifold then test with pressure feed

could be a line to the 'gate has either come loose and is bleeding of pressure
or has split /perished the lines?
dont rule out the lines are all good as could be opening up under pressure,so may be pressure test them to confirm all good
could be solenoid issue ,could test him with pressure feed and switch solenoid on off to check it vents or opens with live power +

all I can think of atm

[zeppelin101]

Check all the hoses first, one of them might have got a bit melty. Been there with my first one years ago, panicked it might have been something severe and simply needed a foot of new hose from the actuator to the MBC

[redlinezak]

I did visually check the hoses trackside but was pretty toasty so couldnt properly check. Could either be a split in the hose to the gate or possibly a blocked vacuum feed to the sensor which if my thinking is correct would cause it not to stay open and keep bleeding air?
Will get the screamer off and see if the diaphragm is stuck closed ( i think it would be closed to cause overboost yes)?

At least everyone is thinking along the same lines as me that it could only be one of the 2 main culprits. If i had thought about it trackside i would have removed the EBC and just run straight to the gate side port to check that as it seems very strange for it to stop working between runs?

Thanks for the suggestions guys.

[800bhp]

How big is the wastegate and what rating are the springs?

[handsomedez]

I've had an EVC 1 and a Greddy Profec B Spec II both with stuck solenoids, so that could be the culprit.

[redlinezak]

How big is the wastegate and what rating are the springs?

Not sure and not sure - it was second hand when i bought it 6 years ago and never opened it up.
Has been fine for the mapping session and the first 7 runs though and suddenly the problem occurred.

I've had an EVC 1 and a Greddy Profec B Spec II both with stuck solenoids, so that could be the culprit.

Yeah thats my second port of call after i check the gate.

[Skyline boy]

S either the wastegate size, too small will over boost, that size turbo I would say 50mm at least, or it's your manifold, a lot f manifolds have poor design. The wastegate pipe should be 'flowing' with the turbo gases to minimise pressure build up, hence the over boost.

[autosri]

It can't be a design flaw if it was working something has to have failed

[redlinezak]

It can't be a design flaw if it was working something has to have failed

Exactly. Iwould have thought the wastegate would be unlikely to fail just like that but i dont know. i have heard of the seizing after being sat for a long time but not out of the blue like this.

Weather permitting i will be having a look at it this weekend so will update any findings.

Cheers

[Skyline boy]

Road testing and dyno testing are not the same conditions though, loading on the car, airflow etc, was it boosting correctly before?

[handsomedez]

Could try a manual boost controller if you have one, that would help eliminate the EVC.

[redlinezak]

I am kind of hoping that the problem will be evident by looking and testing as the only way to try anything out is a trip to the strip or dyno as the car is not road legal. Possibly wishful thinking but can only hope.

The car was ok for the first 7 runs tho Skyline Boy which makes me think that something has failed rather than it be a setup problem. The manifold is a genuine HKS one and came with the Gate so i am assuming that's not the problem. It was also OK with my old turbo for quite a while (admittedly smaller).

Thanks

[redlinezak]

So the wastegate seems to be moving ok when pressure is applied to the side port with an air line.

On my EVC solenoid i have 5 wires - red, black, brown, blue and white.
Does anyone know which ones i need to probe to test if its clicking?

I have also checked all the hoses running to the EVC solenoid and they have no splits or cracks etc.

Thanks

Nath