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Not Holding Boost/boosting?!?!

Jack_Sky

By Jack_Sky,
in Forced Induction Performance

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Jack_Sky Rising Star

Jack_Sky

Posted
Posted

Hey all,

Got a 32 gtst with...

Full 3inch turbo back exhaust, split front/dump pipe, gutted cat, Straight pipe

RB25 neo turbo, running 12 psi

Turbotech boost controller

Front mount intercooler

Adjustable cam gears

Bosch 040 fuel pump

Just Jap coil packs

K&N panel filter

Safc2, tuned by re customs (186kw atw)

since i bought the car there has been a rattling noise coming from around where the turbo is, which ive always assumed was an exhaust leak. However a month ago or so i put my foot down on full throttle. The car started boosting then got to roughly 6,000 rpm/ around id say 9psi or so. and then all of a sudden lost all boost and the revs dropped down to about 2,000 rpm. I was abit worried when it happened and thought it might be a vac line or something, but it never happened again, so i just forgot about it...

So yesterday took my car to get an unexpected timing belt change done, and the mechanic heard the rattle from around the turbo, and thought that it would be that exhaust leak, So they changed the gasket just after the turbo going into the dump, hoping that it would improve the performance and stop the horrible rattling noise.

So i went to pick the car up today, and the rattling was still there, Then they tell me they think its the waste gate. i thought i should take it for a drive before i leave... so began to accelerate, as soon as it began to boost it started shuttering and loosing all boost.

I just want to know, what everyone thinks it might be?

If it is in fact the waste gate, that means a new turbo because its internal wastegate obviously. So where to go from there? I am thinking just going the same turbo so i dont need to re tune the car?

Could it be just vac lines etc?

cheers, jack.

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JonnoHR31 Grand Master

JonnoHR31

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does it still make boost now or not? if so then the wastegate cant be rattling. if it doesnt make boost then pull the dump off and make sure the gate opens and closes fully without any obstructions or catching.

is the rattle only under full load?

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SKYPER Enthusiast

SKYPER

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Wastegate actuator. I had a internal wastegate actuator problem on my car (RB20DET) that caused a similar rattling sound at idle. Turns out wastegate spring inside wastegate actuator bulb was stuffed and didn't hold wastegate on back of turbo closed, so flap on wastegate rattled at idle. Try pulling on wastegate arm on back of turbo (that wastegate actuator arm is connected to) and see if rattling stops, as that is what I could do with my cars wastegate. The fix was fitting another good condition stock RB20DET wastegate actuator. One of the symptoms of a faulty wastegate actuator is loss of peak boost. Exhaust leak between exhaust manifold and turbo makes a whistle sound at higher rpm's, as it plays the gasket like a reed in a instrument.

Edited by SKYPER
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Jack_Sky Rising Star

Jack_Sky

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does it still make boost now or not? if so then the wastegate cant be rattling. if it doesnt make boost then pull the dump off and make sure the gate opens and closes fully without any obstructions or catching.

is the rattle only under full load?

It still makes boost but doesnt hold onto it, it comes on and off. but many times it just completely looses all boost under full acceleration.

Wastegate actuator. I had a internal wastegate actuator problem on my car (RB20DET) that caused a similar rattling sound at idle. Turns out wastegate spring inside wastegate actuator bulb was stuffed and didn't hold wastegate on back of turbo closed, so flap on wastegate rattled at idle. Try pulling on wastegate arm on back of turbo (that wastegate actuator arm is connected to) and see if rattling stops, as that is what I could do with my cars wastegate. The fix was fitting another good condition stock RB20DET wastegate actuator. One of the symptoms of a faulty wastegate actuator is loss of peak boost. Exhaust leak between exhaust manifold and turbo makes a whistle sound at higher rpm's, as it plays the gasket like a reed in a instrument.

Yeh, it sounds like i have the same problem as you did. it rattles on idle and then when the accelerator is applied it tends to go away. i will have a look and see what i can do.

did you make any boost??? cos mine comes on and off. and sometimes itll boost then loose everything???

cheers, jack.

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Jack_Sky Rising Star

Jack_Sky

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Ok, so i took the heat shield off... and moved the actuator arm, it has a bit off freeplay i dunno if its ment to or not. not so much back and forward but up and down... i assume it doesnt matter but thought id check anyways.?

I turned the car on and the rattle sure enough was still there, i pulled/pushed the actuator arm towards the front of the car and the rattle stopped. so thats a start. im hoping its not the wastegate inside the turbo, i think it may just be the actuator after all. im gonna take it back to chasers and see what they think... itll be interesting to see how quick they figure it out. cos they sure didnt figure it out the first time!

any other suggestions as too what i should do???

where could i buy the wastegate actuator and arm for a neo turbo?

Or could i use any other type of actuator(rb25det turbo actuator)?

cheers.

Edited by Jack_Sky
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Wheezy Mentor

Wheezy

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If it is indeed the actuator I would be looking at a replacement R32 RB20 actuator (they are all 10psi actuator). Or as mentioned an aftermarket one.

PROXIMITY, unless there is a griding noise, heaps of shaft play or the exhaust wheel has fallen off the turbo I would not jump to conclusions.

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PROXIMITY Rising Star

PROXIMITY

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Wasnt jumping, but i just had exactly the same thing happen without the noise..

The bearing i guess was not working, it was still silent, would boost then not boost untill the front wheel snapped off.

A stuffed actuator is not going to stop the car revving but a failed bearing/turbo will.

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Wheezy Mentor

Wheezy

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Posted
Ok, so i took the heat shield off... and moved the actuator arm, it has a bit off freeplay i dunno if its ment to or not. not so much back and forward but up and down... i assume it doesnt matter but thought id check anyways.?

I turned the car on and the rattle sure enough was still there, i pulled/pushed the actuator arm towards the front of the car and the rattle stopped. so thats a start. im hoping its not the wastegate inside the turbo, i think it may just be the actuator after all.

sums it up.

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chrisR34GTT Community Regular

chrisR34GTT

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I would have to agree with PROXIMITY, especially considering that you are running 12psi of boost through a NEO turbo. They are only good for 10-11psi, as shown in a thread on R34 turbos.

Have you had a look at the condition of the turbo itself to see if there is any damage to the wheels or housing?

Edited by chrisR34GTT
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Jack_Sky Rising Star

Jack_Sky

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Ok, so chasers are putting on an rb20 actuator today.. Hopefully this will fix the problems that have arrised. if not, looks like ill be up for a new turbo. :)

and im gonna take the boost down to 10 psi when it returns, hopefully itll be alot safer. and then ill pray for the car to keep running until winton in 3 weekends time. Ill be spewing if i cant make it.

will let you al know how it goes.

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Jack_Sky Rising Star

Jack_Sky

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Well, got the car back... Turns out, its the turbo after all.. I had the boost controller on there, and it wasnt liking it.. it was overboosting, even tho the boost controller was on as low as possible. weird i know. so we took it off, now its just running stock 10 psi and fine. its not over boosting, obviously no where near as much power, but its still slideable as ive already found out. haha

ill see how it goes anyway... and when its completely f**ked then a new turbo will be in order...

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