why is my "stock" boost extremely high?

[dwadia]

I just got a boost gauge installed in my sr20 s14, and i realized my boost is going VERY high if i rev it up to the redline or even close. I think it hit 1.7- bar or more, and i am really concerned about this as i'm sure it can make short work of my engine. Without doing the exact psi conversion, i know .85 bar is ~15.2 psi, and 1.05 bar is ~18 psi, so this is very roughly around 30 psi.

I have a gt3071r turbo with a tail 38mm wastegate. I just had an HKS evc-4 boost controller installed at the same time as the boost gauge (which is actually a blitz turbo timer with a gauge in it). However, even with the boost controller turned off the boost is shooting up like this. Judging by how the car felt before and after, i am pretty sure it was doing this before i even had the boost controller, although i didn't have any gauge to read it on.

Now that i'm aware of this i'm just not revving the car much past 4k so the boost doesn't surge up, but i would really appciate any help so i can get it back to its proper wastegate boost.

Thanks.

[ronj]

1 bar is actually 14.7 psi. Is your ecu tuned for a turbo that large???

[JDMark]

the wastegate should have a set psi when you buy it, do you know what its soppused to be at? you sure its hooked up right? and maybe buy an actual boost gauge instead of using a turbo timer.

[punxva]

yea try getting an actual boost gauge on it, and also figure out the boost that your spring is supposed to be allowing at the wastegate

[dwadia]

ronj: thanks for that correction. Nonetheless, the car is tuned to run 18 psi safely on pump fuel (93 octane) and it's running way above that. And my boost controller is not working at all as a controller, only displaying what the actual boost is.

Yes, enthalpy-tuned ecu, 740cc injectors, and many other mods. Is it important to this situation? If so just let me know and i'll list them all.

JDMark: 12 psi. I bought the car with all these mods (except the controller and turbo timer i just had installed). I would assume it's all hooked up right because the previous owner said he was driving it without any issues. He had a Blitz sbc-id which he removed before selling it, and said it should be running at wastegate boost until i installed a new controller. I'll consider the boost gauge, but i don't think it would be reading that far off.

[fliprayzin240sx]

Well something is up with the wastegate. The wastegate should be opening up at a certain boost depending on the spring thats in there. I wouldnt suggest you trying to rev your engine or even drive it, spiking that high will definitely blow your engine.

[dwadia]

JDMark: 12 psi. I bought the car with all these mods (except the controller and turbo timer i just had installed). I would assume it's all hooked up right because the previous owner said he was driving it without any issues. He had a Blitz sbc-id which he removed before selling it, and said it should be running at wastegate boost until i installed a new controller. I'll consider the boost gauge, but i don't think it would be reading that far off.

I take that back about 12 psi. I don't know the preset boost - i bought the car like this and i'm not sure what spring is in there. Is there any way to determine this? I can't get in touch with the previous owner, but anyway, at this point i don't just want to take someone's word for it. I want to actually check the spring somehow and know for certain.

[dwadia]

Well something is up with the wastegate. The wastegate should be opening up at a certain boost depending on the spring thats in there. I wouldnt suggest you trying to rev your engine or even drive it, spiking that high will definitely blow your engine.


Ok, i made a mistake in an earlier posting. I looked at the peak-hold feature again and it was at 2.44!!! I think i'm fortunate the engine is still running.

It seems that regardless of any boost controller issues, there has to be a wastegate problem as you said. Although i don't know what spring is in there now, i checked the tial website and the stiffest one they make is for 1.6 bar/23.2 psi. So even if that's the spring that is in there (HIGHLY unlikely) something is very wrong. I am still quite new to and unfamiliar with turbos, what is the next thing i should do in this situation?

By the way, correct me if i'm wrong but i see no problem in driving it conservatively for now and letting off when it reaches 1 bar, is this ok?

[ronj]

There is somthing definatly wrong with your wastgate!!! 2.44 bar is like 35-36 psi. Check to make sure you still have a vaucuum line hooked up to it.

[ronj]

You can also drive the car all you want as long as you dont push your boost level past like 1.35 bar. That should be about 17- 18 psi.

[dwadia]

Ok, so i checked the vacuum lines and it seems to be that there are 2 connected to the wastegate. I don't know if a wastegate has a "top" and "bottom" per se, but since it's directly on the bottom of the turbo i'm going to call the side farthest from the turbo the bottom.

I want to be sure the boost controller (and more importantly its vacuum hoses) were installed correctly and i'm hoping someone can verify this. I just took pics but i don't know what's up with this, it won't let me post them on here. I can email them to anyone if necessary, but i'll just describe it here. I have an HKS EVC-4.

There are 2 big hoses and one small one coming out of the actuator, arranged in that order. The big hose on one side of the actuator goes into a tee. One outlet of that tee goes to the hotpipe and the other goes to the "top" nipple of the wastegate. The middle hose on the actuator goes directly to the bottom of the wastegate. The thin hose has a tee to allow an even thinner hose out which goes into the firewall (probably for the boost gauge, didn't bother following it). After that (still on the small hose coming out of the actuator), there's another tee with one outlet going to the blowoff valve and the other connecting to the underside of the throttle body. There's also a nipple on the opposite side of the actuator than the three hoses/nipples i just described, which is covered by a rubber cap with a small hole. It's the same size as the nipples for the 2 large hoses on the other side. Should this be used for anything?

I tried to bypass the actuator and see if that corrected the problem. I'm not sure whether i did it correctly, but it didn't help. I just took the 2 thick hoses off the actuator and connected them directly to each other. Since it was no help i put it back the way the shop installed it.

I'd appreciate if someone can verify that all the vacuum hoses mentioned are correctly installed (and of course i'd welcome any other suggestions).