240Z TwinTurbo

iTrader: (25)

Yes, that was referenced in post #19. Strange that you report the valve fluttered because when you block off the bottom port on a IX BOV you lose the pressure on the bottom side of the diaphram helping to open the valve and the effect is the valve doesn't budge during part throttle acceleration. Because the surface area of the diaphram is larger than the surface area of the valve the result is the valve will stay closed. I blocked off my BOV and it surged badly and would only open with abrupt throttle closings.

To the OP, unplug the hose going to your BOV and temporarity cap the line, but leaving the blowoff valve fitting open. Go drive the car and see if if the surge is eliminated and let us know the results.

jameswwt

[quote=mrfred;10016707]my guess is not surge but instead the bov fluttering. its a pretty common issue that can show up at different rpm/boost combos depending on turbo, bov, spring, preload ... a different bov/dv may mostly eliminate it or move it to a different rpm/boost combo. even though i don't think its surge, i think wingless has the best solution provided that your wga can provide the needed part-throttle boost reduction. most people are running 18+ psi wga actuators that can't provide the necessary lower boost.

Hi Mrfred,
do you mean i should lower my WG spring rate? Im running dual spring which my lowest boost pressure is 1.3 bar and currently im running at 1.6 bar.

If i switch off my B/C ive no issue on surge or engine judder during partial lift off.

What is the best option i should try now?

Thanks

jameswwt

Hi 240Z,
yes ive tried capping of the bov line and whenever the boost start to come, the bov will just open. Cant even tell is the surge goes away or not.
My bov setup is direct tapping to the intake and have tried unpluging the silicon hosefrom the intake to my bov but the bov will just open when boost start...

mrfred

iTrader: (50)

[QUOTE=jameswwt;10019078]Are you running a tephra v7 ROM?

jameswwt

[quote=mrfred;10019193]No Mrfred..
Im on Pfc at the moment and mine is an Evo 5...

mrfred

iTrader: (50)

Without a throttle-based boost control option, your only choice is to try different BOV/DVs to see which one works best for your setup.

240Z TwinTurbo

iTrader: (25)

On my car I get bad shutter/surge at part throttle acceleration at the 5psi range. When I unplugged the BOV line a few days ago I could boost the same 5psi, but the surge was gone. With that said, I have a 10psi spring in the bov so anything below 10psi would hold boost (granted there was leakage).

In my case the ability to lightly vent the BOV in that condition resolves the issue, but I am still left with the challenge of how I make that happen.

As MrFred has stated, without trying to control boost/vacuum to the BOV you will likely have to try a different BOV to resolve your issue. Good Luck.

griceiv

iTrader: (2)

tried the -3psi spring yet? No point in running a -10psi spring if you're recirc-ing.

jameswwt

Thank you Guys truly appreciate for your kind sharing & advise.

jameswwt

Hi Mrfred,
what Bov do you suggest? and any link for the throttle-based boost control bov?

mrfred

iTrader: (50)

By throttle-based boost control, I meant throttle-based WGDC control that tephra put into his v7 ROMs.

I'm not much of an expert on BOVs. I've only ever tried stock and the Synapse DV. I can say that the Synapse DV has a ton of adjustability. Lot's of people seem to like the TiAl Q valve. I've heard good things about the Cobb XLE DV/BOV.

jameswwt

Thanks...

jameswwt

I finally switch off my profec b II b/c and you guys know wat?

My car runs smooth like butter even thou my boost now is 1.4 bar and the turbo response is slightly slower but no surge and the power is "MASSIVE"! After PITA for more than a year and after my upgrades, this is the 1st time i really enjoy my car with such smoothness and power...

Should i switch on the b/c again and lower the boost to 1.4bar?
The reason is, if i switch on the b/c i might get the turbo to response faster.

jessmanEVO

iTrader: (7)

I just recently replaced the spring in my tial 50mm bov. It came I painted and I swapped it out to the black one. Its their lowest spring rate. Now the bov will remain open at idle and closes under load like it should. Also, if you haven't already, I'd try changing out the hose to the bov for a reinforced hose like they use for fuel injection and make a dedicated line from IM to bov.

2003evo8GSR

Hey everyone.. I am currently having the same problem.. 03 evo 8 GSR.. Changed the BOV and new vacuum line.. Drives fine until about 6-7k rpm, then BOV abruptly releases as if I let off the throttle completely, but I didn't. Every gear in high RPMS.

Service light code says "turbo over boost"..


Any ideas anyone? Thank you guys much!