R34 GTT air noise?

[JC71]

I drove my ER34 for the first time since I got it, It sat for 4 years in Japan, and i got it 7 months ago, have done a ton of work, garage test ran perfectly. (no air suction sound)

BUT when accelerating (under a load) it makes a loud air suction sound, or anytime I get into the throttle...it sounds like a leaf blower.

I also noticed that it did not seem to have very decent pull or power, and the boost gauge doesn't seem to go much above 0,  its stock other then full exhaust, apex intake, 50/50 bov and front mount intercooler.

this is my first Turbo car so I don't know if this is correct?

I did take a video but for some reason it is very hard to hear in the video, in person it literally sounds like some one has a leaf blower under the hood...my first though was a leak?? however I have check over all lines, clamps, hoses and fittings.

 

thoughts?

Edited July 8, 2024 by JC71

[JC71]

here is the video, again really hard to hear but in person its very loud

[GTSBoy]

Boost leak or exhaust leak.

Boost could be from anywhere, including manifold/plenum gaskets.

Exhaust is frequently head to manifold gasket or from manifold to turbo gasket. Often caused by missing nuts or broken studs.

[JC71]

I will go over it again, a leak would make the most sense and also explain why I have a high idle issue if I plug the iacv in...I have had everything off, inspected, and replaced every coupler and hose in question, new clamps, reinstalled and basically soaked the entire system with soapy water and find nothing...

could there possible be an issue with the wastegate rusted open?? from sitting so long? again the air sound literally sounds like a 3 inch open pipe blowing or sucking air, not just a small passage, very strange.

it does sound like the turbo is creating massive air flow but like its not being diverted or flowing into the intake/cylinders, it seems to have very low and delayed power.

do appreciate the help

Edited July 8, 2024 by JC71

[joshuaho96]

4 hours ago, JC71 said:

I will go over it again, a leak would make the most sense and also explain why I have a high idle issue if I plug the iacv in...I have had everything off, inspected, and replaced every coupler and hose in question, new clamps, reinstalled and basically soaked the entire system with soapy water and find nothing...

could there possible be an issue with the wastegate rusted open?? from sitting so long? again the air sound literally sounds like a 3 inch open pipe blowing or sucking air, not just a small passage, very strange.

it does sound like the turbo is creating massive air flow but like its not being diverted or flowing into the intake/cylinders, it seems to have very low and delayed power.

do appreciate the help

Wastegate stuck open will make the exhaust louder because the turbine is being bypassed but it will not make a sucking noise. It will affect idle but not enough to cause issues. Only way for that to be an issue is if the wastegate actuator rod is so loose that exhaust is leaking out from it. Exhaust leaks are usually not that complicated to spot otherwise. Any leak will be magnified by exhaust visibly leaving soot or heat damage to gaskets, external surfaces of cracks, etc.

Make sure the BOV is not stuck open. If this is running stock ECU/your tune is not speed density get rid of the atmospheric vent and do 100% recirculation. A boost leak test would show if you had a problem there. You can also try capping the throttle body and only pressurizing the intake manifold to see where pressure is leaking out. With the engine off the only path for it to leak out should be the intake valves. 

 

[JC71]

well, no luck again.😞

I got home after work and took the entire system off, intake, intercooler, all piping , connections, turbo elbows etc., inspected everything. Everything that makes up the intake, turbo and exhaust system , manifold intake and exhaust, all nuts were present and tight, all gaskets looked like they were sealing fine, I find no cracks, loose fittings, restriction, leaks, nothing.... I reinstalled it all test drove, same hair dryer/leaf blower sound anytime I give it throttle, and we are talking half to 3/4 throttle, and under 3k rpm's , as with this noise and it being new to me I wanted to make sure everything is good before I push it, or drive it aggressively.  then I swapped out the 50/50 aftermarket bov for the stock 100 percent recirculation version, another test drive, same exact sound. (except no "ppsssh" sound when I let of throttle.)... I wish I had a stock intake to try as it does have a Apexi intake on it and I wonder if this is causing the loud whooshing sound. I also did a few more various leak pressure tests , 5, 10 and 15 psi and found no leaks in the system. wastegate push rod seems to be moving correctly and is connected as well. turbine wheel seems to be smooth ,stable, intact and very little to no play. 

Still seems like a lot of hesitation and low power, doubt I could get rear tires to even spin, I expected a lot more punch based on what I have heard and seen with these 25 neo turbo engines. I have never seen or heard one in person, but can't imagine this is correct.

I am going to try to see if I can get a much better video of this sound 

Edited July 10, 2024 by JC71

[JC71]

I did find a video of a rb25det neo in a r34 gtt with a similar sound, in this video when he is accelerating from inside the cab I hear the same type of air sound, around 45-53 seconds and multiple other times when he accelerates...so maybe its normal and fine??

 

Edited July 10, 2024 by JC71

[Kinkstaah]

Lol. I mean. Yeah you should hear some degree of turbo sound, which is exactly what you think it sounds like, compressed air moving places.

Are you actually making boost? Your car has a boost gauge. Is it indicating it is building boost, or not?

[JC71]

I guess I just didn't think I would hear so much air movement and it being so loud, as it twice as loud as in the video above,  I understand how it works, but figured with the intake and exhaust all being connected to the air created by the turbo system, that I wouldn't hear so much of the air itself moving, as it would be going to the engine intake or out the exhaust.

as far as I know I am making boost, it just doesn't feel like it is being used to increase the engine power or pull, maybe I am just expecting too much from a little 2.5L

attached is the read out of my boost gauge during different stages:

 

Edited July 10, 2024 by JC71

[Kinkstaah]

I mean, if the motor stock and you have a boost leak, (like a pipe has come off etc) you will barely able to move. I don't mean "drives like a 2002 corolla" I mean barely able to move the car at *all*

That gauge is (mostly) normal.

I say mostly because with a stock turbo and stock everything working normally, you'll hit that green line very easily/quickly. It's not like it will only finally reach there at 5000+RPM after slowly building to it.

It it *does* behave like that, then you have a leak.

If it doesn't, and the boost gauge is more or less pinned there any time you're on the throttle from ~2000rpm upward, then this is normal - the cars run 7psi stock. That's right between 0 and +1KG/CM (which is 14.22psi)

If it's a manual, they do 0-100 back in 1998 of about ~6.1s to 100. The autos are about 7s.
 

[GTSBoy]

I'm thinking that if it is struggling to make boost....the turbo is damaged.

[Milkmun]

On 10/07/2024 at 10:55 PM, GTSBoy said:

I'm thinking that if it is struggling to make boost....the turbo is damaged.

Agreed, sounds like turbo issues. Pull off and inspect.

[JC71]

turbo removed and inspected, actually hoping to find a broken turbine shaft or something, (would explain a lot) but it looks great, no play or noise of bearings, solid connection on center shaft, both wheels and housing look fine inside and out, actually a lot cleaner and better condition then I expected...so I put back together and took for another drive, since I now seen other videos with similar sounds, I pushed the rpms' higher from 4-6k range, and got anywhere from 5-7 psi boost boost being created by turbo. so it appears turbo is making boost fine, however still the sound remains the same, the type of sound I would image if one side of the turbo wasn't connected to anything, (the sound of a leaf blower or hair dryer wide open end) is there anyway something could be preventing the air that is being forced out of the turbo to not be directed into the engine intake properly??, I checked all piping for blockage etc. none found.   still the power, torque and acceleration seem low, as it almost feels like the boost that is being built up is actually holding the engine power back and or its not being directed into the intake properly? I am tempted to make a super short U pipe to go right from the turbo out to the stock intake pipe and completely eliminate the intercooler and piping system just to isolate it.

Edited July 11, 2024 by JC71