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Car Wont Boost After Rb25 Turbo Install

Jden

By Jden,
in Engines & Forced Induction

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Jden Enthusiast

Jden

Posted
Posted

Hi Guys,

Changed the stock turbo on my rb20 yesterday for a s2 rb25 one and it wont make any boost at all.

Drives fine off boost and as soon as you get into positive pressure its shudders really bad and wont go past 0.

Car is also Idling abit high (intercooler piping leak?) but this shouldnt cause it to not build boost?

Any help would be muchly appreciated!

Jden Enthusiast

Jden

Posted
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Did you leave a rag in the intercooler pipe work???

It's allright... everyone dose it.

No rags in the piping lol. Any other ideas of what It could be?

What about the nipple for the actuator? I drilled and tapped it into the elbow this should be fine yeah?

Not really looking forward to pulling It all apart again lol :)

GTScotT Grand Master

GTScotT

Posted
Posted

by any chance you did spin the shaft and stuff making sure both sides of it spin right lol, like u havent shit an exhaust wheel without knowing it have you haha

other than that look for big leaks, but somehow i doubt it.. based on the offboost drivability i mean

MrStabby Grand Master

MrStabby

Posted
Posted
Car is also Idling abit high (intercooler piping leak?) but this shouldnt cause it to not build boost?

Are you saying that you suspect an intercooler pipe leak, but that an intercooler pipe leak wont stop the car building boost? Because it will - the boost will leak out!

Are you getting black smoke out the back? If you have a boost leak it will run very rich and you'll get black smoke. Perhaps so rich that missfires/shudders.

If its not a boost leak check that the wastegate isnt stuck open (you should be able to move the actuator rod with your hand, or just apply 10psi air pressure to it and watch it move). But i dont think your symptoms match a stuck wastegate.

Jden Enthusiast

Jden

Posted
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Are you saying that you suspect an intercooler pipe leak, but that an intercooler pipe leak wont stop the car building boost? Because it will - the boost will leak out!

Are you getting black smoke out the back? If you have a boost leak it will run very rich and you'll get black smoke. Perhaps so rich that missfires/shudders.

If its not a boost leak check that the wastegate isnt stuck open (you should be able to move the actuator rod with your hand, or just apply 10psi air pressure to it and watch it move). But i dont think your symptoms match a stuck wastegate.

Thanks for the help MrKotter, I did get abit of black smoke out the exhaust when I first started it and it did feel like it was missfiring but really violently much more so than when my coilpacks died.

And I cant seem to move the actuator rod at all but the flap is closed not open?

Thanks again for your help mate!

Oh and also to everyone else, yes the exhaust wheel is still there and spins freely

MrStabby Grand Master

MrStabby

Posted
Posted
Thanks for the help MrKotter, I did get abit of black smoke out the exhaust when I first started it and it did feel like it was missfiring but really violently much more so than when my coilpacks died.

And I cant seem to move the actuator rod at all but the flap is closed not open?

It will be very stuff to move by hand, maybe too stiff. And the actuator pushes on it to open the WG, so you need to try to move it in the same direction. But yeah, its almost certainly not stuck open if you're using the stock dump, and if it was you probably wouldnt be able to move it by hand anyway......so keep looking for the leak. Are you sure your new boost nipple is airtight?

MBS206 Grand Master

MBS206

Posted
Posted
Thanks for the help MrKotter, I did get abit of black smoke out the exhaust when I first started it and it did feel like it was missfiring but really violently much more so than when my coilpacks died.

A boost leak is a much more violent miss fire and cut, as the car is reading that it has 3 times as much air going in as really is, so it throws in 3 times as much fuel as needed, affectively flooding the motor.

Jden Enthusiast

Jden

Posted
  • Author
Posted
A boost leak is a much more violent miss fire and cut, as the car is reading that it has 3 times as much air going in as really is, so it throws in 3 times as much fuel as needed, affectively flooding the motor.

Cheers guys, looks like I'm definately looking for a boost leak then, thanks for the help everyone.

Will report back once fixed.

Jden Enthusiast

Jden

Posted
  • Author
Posted (edited)

Hi Guys,

So I took everything apart and put it all back together again, started her up and she seemed fine idle better than last time and much lower too (bout 900).

took it for a drive up the street and when I stopped at the intersection and put it in neutral the car revved by it self upto about 5-6k almost like the throttle was stuck open?

popped bonnet and checked throttle cable and it seemed to be fine, so I started it back up again and managed to put it into gear and it stopped freerevving and I babied it home.

WTF is going on? more boost leaks? didnt get it up to temp so I havent tried to get boost yet.

Thanks guys, this is driving me crazy :)

edit: Just started it up again in the garage and its idling really high again, whats the best way to find the boost leak? soapy water around the silicon bends?

Edited by Jden
scotty nm35 Grand Master

scotty nm35

Posted
Posted

Manifold leaking? The problem is after the throttle body I would say, a gasket probably need to be replaced. You can try spraying around the area with carb cleaner to find the leak.

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