low 5psi of boost pressure on stock setup s14 SR

[nissan_star]

My setup is a s14 sr20det in a s13. I have a Megan O2 housing, HKS Downpipe, a test pipe and a 3" exhaust all the way out the butt. On the intake side everything is stock s14 SR, except filter, so MAF, sidemount, BOV etc... The wastegate/turbo and mani are stock too.

I just got an autometer boost gauge so I could put on my MBC. Put it on and it was set to 14 psi but spiked to 15 once so i turned it down to like 10psi (i have bad tires so there was no reason to have power that i have no chance of putting to the ground). When it was set to 10psi, it would spike to like 14psi and 13psi in 2nd gear. Being nervous about the different numbers, I took off the MBC to see what the boost gauge would read stock.

5psi, with no spiking.

I checked all the charged air pipe connections and they are tight, I also idle at about 19.5 in/HG VAC. I dropped the engine in about a week ago and tightened every exhaust bolt possible, so it shouldn't be leaking on the hotside unless there is a pinhole somewhere.

If anyone has any thoughts on why I only have 5psi on a stock setup and why I have the 4psi spikes, please share. I am going to take off the SMIC to check it for leaks and see if something is wrong with the wastegate actuator after work.

thanks for reading!

[USMCgetsome]

where is your vacuum source for your wastegate coming from. Is it an independent line or did u "T" off of another line?

[nissan_star]

where is your vacuum source for your wastegate coming from. Is it an independent line or did u "T" off of another line?

don't recall, I thought I got everything hooked up as it was stock, but i didn't work by myself.

The MBC was on a line tee'd off of the pipe right after the SMIC straight into the wastegate, is this the line you are referring too?

[nissan_star]

I checked my piping and saw no obvious leaks or loose connections, the SMIC looked in good shape with no cracks or anything besides a few dented fins and after more research I believe the wastegate is hooked up correctly.

My theory now is; because I am using all stock piping from a s14 SR there is actually 2psi of pressure loss from the wastegate vacuum to the Boost gauge and the other high boost readings i had when the MBC was on is due to boost creep.

I am going to replace the wastegate line though because the rubber looks almost dry rotted then re-tee the boost gauge line to the wastegate line or vise-verse and hopefully I will get 7psi, if not, then problems.

[nissan_star]

tested the intercooler in a deep sink full H2O of and found that it was leaking big time at one of the flange fittings. The previous owner did not take the time to fully remove the metal/paper gasket before putting liquid gasket on so it blew through.

hopefully that was the only leak in the system and hopefully this helps someone later