Rb25det won't build boost?

[Joshhankins5]

Hi I'm new to the forums. As the title says my rb25det won't build any boost. I just swapped this motor into my s13 coupe and it runs great but won't build any boost at all. Zero psi. Is the wastegate actuator stuck open? How can I check it? I don't think I have any boost leaks or anything. I also haven't gotten my bov welded on my ic piping yet. So if it spooled I would have turbo surging but I don't hear that at all. It also blows a small amount of white smoke first drive? Is this normal for a motor that hasn't run in months?
Thanks any help is appreciated

[Sills]

Wouldnt be too worried about the smoking on an engine thats sat for a while. Is the car limping? It will drive absolutely horribly without any boost. Make sure you dont have any open vac lines leaking boost, theres one on the back on the manifold for the Skyline gauge sample, I used this for my boost gauge sample in my S14. otherwise it should be plugged. Also check your intercooler piping, I blew out the couplers time after time until I finally got it all fitted properly. Go to your wastegate, see if the arm has any play when you try to pull it back in towards the actuator to close the wastegate, suggesting it would be stuck open. Also watch the wastegate actuator arm, Have someone rev the engine until it should be in boost and see if the arm moves. If its not moving then its either stuck or not seeing any boost which could be a symptom of a leak. You should be able to hear a boost leak. Look over the intercooler piping very carefully, that would be most likely.

If the car runs alright, its probably a problem with your gauge. The car will not run well at all if its actually making no boost. You should be seeing 7psi from a 25 turbo.

[Joshhankins5]

I have a greedy intake on it. I have all the vaccum hoses hooked up right. My ic piping is all good. I used a compressor to shoot air to the wastegate and it opened and closed fine. It runs smooth no jumps on idle. And it drives fine but I feel no boost at all, no power, but drives fine. The turbo has little to no shaft play and spins freely. Is it the turbo out?

[Sills]

I have a greedy intake on it. I have all the vaccum hoses hooked up right. My ic piping is all good. I used a compressor to shoot air to the wastegate and it opened and closed fine. It runs smooth no jumps on idle. And it drives fine but I feel no boost at all, no power, but drives fine. The turbo has little to no shaft play and spins freely. Is it the turbo out?

What makes you say the turbo is making no boost? When my couplers would pop and make no boost the car literally would not go past 2500 revs and usually stalled. The DET engines do not like to run without boost at all. Is your bov stuck partially open allowing it to mostly leak out?

[Joshhankins5]

What makes you say the turbo is making no boost? When my couplers would pop and make no boost the car literally would not go past 2500 revs and usually stalled. The DET engines do not like to run without boost at all. Is your bov stuck partially open allowing it to mostly leak out?

I havent got my bov welding on yet. So it has no bov on it. If it built any boost I would hear turbo surge from air rushing back to the turbo after letting go of throttle and I don't hear that at all. My gauge reads no boost just vaccum. It feels super weak, I don't feel any boost hitting at all.

[Sills]

I havent got my bov welding on yet. So it has no bov on it. If it built any boost I would hear turbo surge from air rushing back to the turbo after letting go of throttle and I don't hear that at all. My gauge reads no boost just vaccum. It feels super weak, I don't feel any boost hitting at all.

If youre sure about everything else the only thing that I can think of would be that the fins on your turbo are ruined. Even that sounds pretty unlikely but it seems like a possibility right now. Remember the stock turbo only makes 7psi, It wont be super loud or come on super hard. Mine didnt even flutter with no bov at 1 bar of boost (Different turbo though I guess..No antisurge though)

Sorry thats all I guess I can help you.. Wish I could take a look at it firsthand.
Id just inspect all the Ic and manifold for any spots where air could escape or where vac lines may be hooked up inproperly. Aside from knowing they are a great product, I unfortunately am not very familliar with greddy intakes so i cant really help you there. Other than making sure the proper gaskets are in place as the air will escape from any slight place it possibly can since high pressure will always move to low pressure.

Not doubting you, or trying to talk to you as if you dont know what you are doing. Just speaking every possibility I can think of.

Best of luck.

Edit- Also I still wouldnt rule out the wastegate. It still could be slightly opened. If you cannot find any other problems elsewhere id make sure that its as tight as can be on the adjustment screw if you have one. Possibly pop the downpipe and elbow off and visually inspect it.. But I know what a pain it can be to get those elbows off.. Ended up breaking off a couple of those bolts when I put my new turbo on mine.

[Joshhankins5]

If youre sure about everything else the only thing that I can think of would be that the fins on your turbo are ruined. Even that sounds pretty unlikely but it seems like a possibility right now. Remember the stock turbo only makes 7psi, It wont be super loud or come on super hard. Mine didnt even flutter with no bov at 1 bar of boost (Different turbo though I guess..No antisurge though)

Sorry thats all I guess I can help you.. Wish I could take a look at it firsthand.
Id just inspect all the Ic and manifold for any spots where air could escape or where vac lines may be hooked up inproperly. Aside from knowing they are a great product, I unfortunately am not very familliar with greddy intakes so i cant really help you there. Other than making sure the proper gaskets are in place as the air will escape from any slight place it possibly can since high pressure will always move to low pressure.

Not doubting you, or trying to talk to you as if you dont know what you are doing. Just speaking every possibility I can think of.

Best of luck.

Thanks for the help man, I'll defiantly re look over everything you mentioned just in case.

[Sills]

Thanks for the help man, I'll defiantly re look over everything you mentioned just in case.

Ill keep my eye on this thread. Please post when you find the issue! Im actually really curious as to what it would be! Best of luck with it!

[Drake_fist]

Sounds like a fuel problem or boost leak have you changed the fuel filter, or fuel pressure regulator is it a aftermarket regulator?fuel pump making any werid noises? Any leaks around intake or throttle body gasket?

[Joshhankins5]

Sounds like a fuel problem or boost leak have you changed the fuel filter, or fuel pressure regulator is it a aftermarket regulator?fuel pump making any werid noises? Any leaks around intake or throttle body gasket?

I figured it out couple months ago. The turbo had no exhaust turbine lol it was gone. Replaced the turbo now it boosts fine.