I call my car "the boost creep", also makes a fluttering noise.

[240z4u]

Hey guys, I have started turning up boost for tuning. I am having boost creep problems now. I am attempting to run 18psi right now and it varies from 18psi dead on to about 21 or so. Its enough variation to set off the alarm on my Profec A.

I also get a compressor surge chugging noise under high boost. I don't know if its related. I have a crappy turbo xs BOV so it might be blowing open under boost. I haven't tried capping it yet.

The feed to my external wastegate is off of an internal wastegate port on a t3/t04e turbo. I am using a TIAL wastegate.

One thing I forgot to do was enlarge the opening from the exhaust housing to let more air through. I think this may actually be the issue.

Also, on my profec A, I have fairly long (read 2-3' vac lines running to the boost solenoid. I think maybe they are too long and effecting the reaction time of the boost controller.

Thoughts besides these anyone? This is a problem regardless of temperature, but definitely rears its head more when its cool outside.

Thanks fellas - Evan

[Carl H]

your vac lines are def too long, but i do have this same problem but more so when its cold out...cept mine is a bit more drastic 14psi base becomes 20psi.i think its mainly due to the wg, it might not be venting enough air or there is a leak in the intake track.

[240z4u]

Carl, its hit or miss. I have had it boost 5psi over set limits.

Ill move the solenoid closer and shorten the lines (certainly can't hurt). I am wondering if the surging I am hearing is the boost controller struggling to control boost.

I toyed with the settings on the profec A and its boosting stable at around 1 bar now. I need to get this thing on the dyno and setup the boost controller. I know its part of the issue.

I spoke to a buddy who has a 280z with a zxt motor swap that I built. He was having the exact same problem and porting the exhaust housing outlet cured his problems.

Ill keep you updated.

Evan

[240z4u]

I re read my installation manual and it appears there are actually a couple ways to connect the boost controller to the system. I will be trying plan B this weekend. Ill also move the control solenoid closer to the action (I hate putting it where it will get hot though, so maybe a heat shield will be needed).

Evan

BTW, there is a few dials on the greddy that when turned up too high make my car overboost.

[jdmser]

I was reading a couple different post guys had made about z31s and over boosting. If you have a t3/t04e with the 7 bolt Nissan flange like me, this might help you out. They've been smoothing the entry way to the wastgate and enlarging the wastgate hole. They've seen results of up 19psi with no creep. I'm in the middle of doing right now. Now, this was for the internal wastegate but, if the exhaust is skipping over the hole I don't think that would matter.