Help....6psi wastegate runs 2psi?????

[nelson8708]

On my old sr-t25 setup it ran 2psi for some reason. I tried two different wastegates...one which came off a buddies sr that ran 7psi and mine still ran 2psi. My boost source was first a vacuum line from the intake, then the brake booster vacuum line, and finally the hot pipe right after the turbo. Even with all those different sources it ran 2psi. I was fine with it because it was still decent in the 14second range. Well with my new setup with 6psi wastegate it still runs 2psi. ....i dont get it. New everything and it still runs 2psi. The boost source is off the hot pipe. I have been on 2psi through two differnt motors and two different setups now. One thing that bothers me is that on the old setup i put a mbc in line with the wastegate and turned it to zero and it ran 7psi like it should. I am going to try that with this setup to see what happens. Its just weird that this car only like 2psi. Any suggestions on what this could be let me know.

-Nelson

Here is a link to my build if you need pictures.

zerothread/307335

[480sx]

What happens when you disconnect the wastegate?

When you do this, make sure you give it light throttle so you dont overboost your engine. See if you can isolate the problem to the wastegate.

[Florida240sx]

checked your gauge? What does it feel like? 2psi and pulling 14sec 1/4miles doesn't sound right to me

[nelson8708]

checked your gauge? What does it feel like? 2psi and pulling 14sec 1/4miles doesn't sound right to me

On my old setup i didn't believe how fast 2psi was either so i borrowed a buddies boost gauge that he didnt install yet and use it to make sure it was 2psi and it was. 2psi on this setup feels very slow. It is breaking up in the higher rpms and when it hits 2psi the open dump is not very loud so something is off. I gapped my plugs to .28 .....if the mbc doesnt do anything i will unhook the wastegate to see what happens. I found out that my v-band is bad so i ordered another one today.

[GEO]

DEF a boost leak.

[turbo2nr]

+1 for leak.. i have one that does almost the same.. its been 3 months and i still cant find it.. it sucks

[GEO]

Check your intercooler piping and amke sure your have a good seal bewteen the manifold and the turbo.

[Florida240sx]

My downpipe kept liking to lose bolts so always had turbo>DP exhaust leak. I always kept spare bolts in my car.

[nelson8708]

Check your intercooler piping and amke sure your have a good seal bewteen the manifold and the turbo.

i pressure tested the pipe from the turbo discharge to the throttle body and there are not leaks. The weird thing is if i put a mbc inline with the wastegate and turn it to zero it will run 6psi.

[GEO]

Make sure the wastegate is getting the pressure from the FPR line.

[nelson8708]

i have had the line coming from a T in the fpr line, Brake booster line, and right now it is off the hot pipe.

[Tx-Sx-FS]

not to make u sound or look dumb, but you talk about the MBC, is the MBC installed backwards?? not sure if u had in installed in both setups or not so just eliminating possibilities.

[nelson8708]

no the mbc is not backwards. If it was i would be like running with not line to the wastegate and hit crazy boost levels (ball and spring type).

[GEO]

Werid, maybe its got a 2 psi spring? lulz

[nelson8708]

i wish it was something that simple. Its just weird that there are no constant variables to try to narrow down the search. I mean two different setups, everything is different from the intercooler, piping, turbo, wastegates, and even a motor swap. I am just going to run with a mbc set to zero and let it run 6psi.

[Florida240sx]

Are you using a gasket where the wastegate is? Mine burnt itself up and so I used spray gasket and never had any problems. Leak somewhere.

[540sx]

sorry if this is a stupid question, but why are you running your boost reference through a vacuum line. and not direct from manifold to mbc and then to wastegate.

vacuum and boost are totally different things If I am not mistaken.

thought vacuum lines are supposed to help get rid of turbulent air or something by letting it get sucked into the intake?correct me if I'm wrong.

[480sx]

Er, what? What else would he run his wastegate source in..? Are you thinking that vac line is going to explode when it sees boost?

Vac lines do WHAT with turbulent air? Idk exactly what your talking about or what you read, but thats wrong.

Vac lines are good for boost/vac. You use them for everything. Vac lines are simply a means to supply any device outside your motor with a 'power source', or the means to operate.

[nelson8708]

I'm not sure what he is talking about but, i did find the problem. I ditched the fmu when i put in my 460 injectors and not touching anything else other than taking the fmu out and having to change my vac line setup a little bit, it ran wastegate pressure. I checked to see if the fmu had a vac leak and it didnt. I might have been running wastegate pressure the whole time but, my boost gauge got a funky reading because the fmu was in line with it or something but, i dont have the 2psi problem anymore.

But, i recently had internal engine problems that i have yet to figure out.