Bov Making Car Hunt?

[sleptema]

Hi all.

Tried to search for the issue, but I didn't have much luck finding anything relating directly to my issue.

Car has a stock blow off valve, plumbed back. Decided to make a plate to block it off, you know for flutter/dose/compressor surge whatever you want to call it.

Car runs great, starts fine, idles fine, holds boost, flutters...

But if I am idling and rev it slightly, then take my foot off the throttle, it hunts for a while then goes back to idling fine. Sometimes it drops to 100-200 rpm, sometimes just to 600, stalled a couple times. It doesn't ALWAYS do it. It is mainly a concern when I am in traffic and need to move forward slightly. Black smoke also comes out the exhaust when hunting. Rich?

Is it because it was tuned with the plumb back blow off and it is expecting that air for idle and isn't receiving it? I have blocked the vacuum line going to the bov and the plumb back pipe. I haven't tried plumbing the bov back in and taking out the blanking plate. Will do that soon and report back.

R34 gt-t rb25det neo
Garret low mount on 18psi
avc-r boost controller
power fc

supporting mods

[Ben C34]

It's because of the reverberation caused affecting the afm.

The ecu sees it as more airflow and adds fuel.

Flutters are not cool enough to put up with your car running shit.

Edited January 30, 2014 by superben

[ARTZ]

[sleptema]

Yeah, think I may be plumbing it back in. Cheers for the quick help.

[75coupe]

I say long live the atmo bov, just dont put it near your afm, simple...

[sleptema]

Yeah well I think I will just go atmospheric for the time being, until I can afford a ecu that uses map tuning.

[Ben C34]

Or plumb it back and live a happy life.

[75coupe]

I use pfc and have no probs, would like a return pipe but its a long way back to the hot side from my bov, one day I 'll have a hard line, but it works fine the way it is, no map ecu needed

[ARTZ]

Or plumb it back and live a happy life.

this...seems pretty simple to me mate...you changed something and it made it worse...

Now 'Im not the sharpest tool in the shed but i'd thunk the smart thing to do would be change it back

[sonicz]

Yea plumb it back and it should keep vacuum/boost distortion to a minimum. Probably enough to solve your problem. You will probably get better fuel economy too.

[75coupe]

Fuel economy and skyline..... Your funny...

[sleptema]

I've plumbed it back in, obviously it has fixed the problem.

No I mean for flutter I need a map ecu, because I can't have an afm tune or this will continue to happen?

[75coupe]

hmm like I said I have afm tune, with atmo bov no prob, but ofcourse do what works for you

[89CAL]

Mine fluttered with an AFM, had the bov plumbed straight into the intake pipe at 90 degrees, not facing the turbo as recommended. Never had any issues

Mine didnt flutter like crazy because I softened the bov but when it did it was fine

[sonicz]

Fuel economy and skyline..... Your funny...

Some people get 600km to a tank. Thats not bad. I only get about 400 but thats because the auto is slipping and the stock ECU is probably running the car rich these days due to old equipment.

[niZmO_Man]

I was getting 9L/100km in my old R32.

[sleptema]

hmm like I said I have afm tune, with atmo bov no prob, but ofcourse do what works for you

AFM tune with atmo is fine, talking about flutter.

[sleptema]

Mine fluttered with an AFM, had the bov plumbed straight into the intake pipe at 90 degrees, not facing the turbo as recommended. Never had any issues

Mine didnt flutter like crazy because I softened the bov but when it did it was fine

If it flutters, the BOV is supposed to be blocked, doesn't matter if it is plumbed or not..

[89CAL]

Yeahhhhh.... It will flutter blocked or with the BOV spring tightish. It isnt 'supposed' to be bocked

[sleptema]

Yeahhhhh.... It will flutter blocked or with the BOV spring tightish. It isnt 'supposed' to be bocked

How do you tighten the BOV spring?

I didn't think the flutter would have have as much as effect as it did on my car, it is a low mount garret with a LARGE FMIC, and no forward facing plenum. So much frikken pipe work, wouldn't have thought it would have made it that far back..