Bov Causing Shudder

[conan7772]

Had boost leak from stock BOV so fitted a Turbosmart Kompact Plumb back.

Fixed the leak but now have shudder.

This flutters on release and shudders the car quite a bit around 80 km/h and over.

Assuming it's the recirc pressure causing the problem ?

Any way to fix this ?

VQ25DET

cheers

[Artwear]

Hey mate, i dont have a solution, but i did have the same issue, also did it under load up hill at lower speed on gear change.

Another thing i found was with the bov and hi flow i had the engine cut out at max revs in 2nd, watch out for it, ull.head butt the windscreen!

Happy hunting mate, im keen to see if theres a solution!

[conan7772]

Have you tried blocking of the plumb back and release to atmo ?

[Artwear]

Yeah, made little difference for me, though i do have an intake or air flow issue aswell. Its easy enough to do so it cant hurt to try.

I ended up reverting back to stock for now.

[R31 POWER]

Have you tried it on a softer setting?

[conan7772]

aahh that was my next question ?

didn't think it was adjustable .

there's no mention of adjustment in the instructions...

aren't they just set to a certain spring rate ?

Edited October 5, 2015 by conan7772

[conan7772]

hmm just noticed on their website, under nissan plumb back bov which has the matching flange, it says all Stagea models require dual port.

strange as the factory bov isn't, must work differently...

[scotty nm35]

I have a dual port I would swap you for, I prefer the single, but the dual is adjustable so you can tune out the stuttering.

At least now you know why the stock BOV leaks, it's done from factory to remove that stuttering.

[Artwear]

Yeah i rekon from what scotty has said, the stock acts differently to a standard bov, like a pre built "leak" to adjust factory boost levels

[Artwear]

Speak of the devil! Haha.

Can an aftet market tune adjust for the aftermarket bov? I assumed that the correct way to get around it.

[Brick]

There are two things that can cause this. Too hard a spring (turbosmart can supply a softer Spring) and in some cases (mine one of them) there is a retractor in the bov control vaccine line. I replaced that line and the shudder went away.

[conan7772]

so the Nissan Kompact Plumb Back isn't adjustable ?

what about blocking the recirc ?

if you can tune it out with the dual port, it must be the recirc pressure causing it

Edited October 5, 2015 by conan7772

[conan7772]

this looks like vent to atmo, whats are the white vac lines doing ?

he's also blocked one off on the plenum.

Edited October 5, 2015 by conan7772

[Brick]

, time for a new mechanic. The line should not have changed. That is all kinds of wrong

[YangLIU]

i changed from Blitz plumb back --> Stock BOV --> Turbosmart Kompact plumb back

Blitz is adjustable with soft spring --> has shudder (pigeon sound)

Stock BOV --> big leak over 17-18 psi

Turbosmart kompact --> has shudder (pigeon sound)

i did some changes below:

1. keep BOV vacuumto plenum (no.1 in screenshot)

2. join stock ECU boost sensor with stock boost gauge sensor together and connect to plenum (keep using stock boost gauge sensor vacuum (no.2 in screenshot)

3. using a long vacuum pipe connect from stock ECU boost sensor vacuum source to intake pipe (share with stock boost controller solenoid) (no.3 in screenshot)

that could slightly reduce the shudder but can't 100% sort it.

[scotty nm35]

A tune can sort it to some extent, but it really needs to remain plumbed back to the intake, or the afm will misread the airflow and dump fuel. You need a MAP ecu to vent atmospherically without affecting the tune.

You can block the bov but you will get sick dose, and probably snap the turbine off it's shaft.

No shudder on mine since the first tune, I have had the Kompact on for 5 years now, very reliable and quiet with the stock airbox.

[Beregron]

I replaced the vac line and am using the standard spring which still had some shudder before the first tune (emanage).

Since the first tune it never skips a beat

[Daleo]

Jesus Christ, All that extra wiring and lines is hurting my brain! Don't you at least try to hide extra wiring in your engine bay?

Why have you connected the BOV to the wastegate pressure reference line?

The BOV needs a pressure/vac signal on the engine side of the throttle body. Without vacuum; the BOV won't open when the throttle closes.

[conan7772]

Oh sorry I've mislead everyone, that's not my engine bay.

Mine is stock all except for BOV.

I posted that pic for reference for possibilities about venting to atmo.

[BoostdR]

I put a grub screw in the OEM BOV bypass, no sick dose sounds and no studder, but that could be because my Hypergear SS2 is currently hella laggy. Did pick up a noticeable improvement is response with an extra 2psi at the same boost setpoint.