Turbo is surging, BOV is fine, what else could it be?

[SketchyRollin564]

So since day 1 of having my car running its been surging and not blowing off. When free rev the engine from the throttle body, and let off, i hear the flutter come out of the intake filter, and not the blow off valve, which is on the cold piping. At first i thought the BOV was too tight, so i loosened it, but then it was just sucking in air at idle, and it STILL surges. When i free rev it from the TB, i still hear it from the filter, and ill barley feel it come out of the BOV. When im driving the car under load, and i hit full boost (9psi), its the same thing, no BOV sound, just surge

The BOV is a fake greddy type-RS, made by BMPC. Engine is a redtop SR, turbo is a t25

i figured the BOV just sucked and posted a WTB thread on a local forum for a real BOV. This dude had an extra CX racing bov, which is basically a type-S knock off. I heard it on his TT 300zx and i know it works, then we tried it on my car, and played around with the spring, and it still just flutters, and doesnt make the distinct noise that a type-S or type-S knock off should. This being said, its not a faulty BOV preventing it from blowing off properly, theres gotta be something else


Is there anything else that would prevent the BOV from working properly? Couplers, turbo itself, wastegate?
He said to try blocking off the plate for the cold side and just trying the BOV on the hot side to see if it works. In theory it should work best or just as well on the cold side, since as soon as the throttle body shuts, the air can go out right there, but it barley does at all


thanks in advance for any help

[bersh240]

do you have a good vacume source for the line?

[SketchyRollin564]

the vaccum line from the BOV goes to the little nipple above the throttle body. Its the top middle one

[AZ89two4Tsx]

Ahhhhhh, might have the same problem. Too bad my car died today...ugh..

[zach-Ka]

Idk if this is your problem, but I had to take one of the springs out of my BOV for it to stop surging. It's worth a shot...

[kouki munster]

Make sure that you are actually getting vacuum from the nipple that you are using, some of the nipples around the tb don't pull vacuum.

[bersh240]

ya the sources near the throttle body are kinda hard to figure out sometimes. you want one thats BEHIND the throttle body for vacume. anything infront of the tb is gona be a boost source for like your wastegate actuator.

[AZ89two4Tsx]

Kind of a threadjack here, but it might help some...

My car was running fine when I got it, apparently it was tuned for the boost leak that must have gotten overlooked; torn coupler. Anyways, I changed out the coupler and ended up having to turn the boost WAY down to overcome the lean a/f ratio. Now I'm getting compressor surge. I have no clue why as it's even running lower boost now. Was completely fine before I changed out that coupler....

...hks sqqv, vented to atmosphere. Tuned on Power FC.

[Chaluska]

The BOV is a fake greddy type-RS, made by BMPC.

First problem... spend the 140 bucks and get an authentic.. for reliability sakes.. do you REALLY want to tear down that s*** BOV after 2 months to replce the syran-wrap diaphram that will tear on the first 10 psi spike?

Second problem, the only line that pulls DIRECT vaccum of the intake manifold, is the far right (out of 4 pipes sticking out from the front, 3 are 1/16th nipples, and the 4th is the 1/8. you can verify this with a boost tester... that costs 1/10th the price of your s*** BOV

[SketchyRollin564]

The BOV is a fake greddy type-RS, made by BMPC.

First problem... spend the 140 bucks and get an authentic.. for reliability sakes.. do you REALLY want to tear down that s*** BOV after 2 months to replce the syran-wrap diaphram that will tear on the first 10 psi spike?

Second problem, the only line that pulls DIRECT vaccum of the intake manifold, is the far right (out of 4 pipes sticking out from the front, 3 are 1/16th nipples, and the 4th is the 1/8. you can verify this with a boost tester... that costs 1/10th the price of your s*** BOV

For now, since i know the one i have works, i dont want to spend that money yet till i can figure out for sure why its not working. If i can get the one i have now to work, then why not put that money twards something else important?

also from what i remember, theres 3 on the top and 3 on the bottom. Are you saying to go with the one on the far right up top or on the bottom?

[kouki munster]

The easiest way to do it is to pull the vac. lines while it is running until you find one that sucks, then hook the bov to that one, provided that the line you just pulled doesn't go to the fpr or something else that needs its own dedicated vacuum source.

[SketchyRollin564]

well i checked today, and i pulled the line off that goes to the blow off valve, and it definatley sucks

so would there be any other factors in this? like a s*** wastegate or something? even though that doesnt go to my bov at all

i hear people T off their wastegate to their blow off valves some times

i feel like a retard, but i honestly have no idea what any of those vacuum lines do, or what they are there for

[terry_240sx]

so would there be any other factors in this? like a s*** wastegate or something?

nope. the wastegate doesn't have anything to do with the bov.

i hear people T off their wastegate to their blow off valves some times

yep i did this and it has been working fine for me. my bov is an hks ssqv.
i don't think there is any way to prevent the turbo from ever surging. I don't even think surging would hurt your turbo that much. I can only get my hks to sing when i'm actually driving.

[Frenshawas]

I had the same problem with my greddy Type S and it was stuck shut. i backed the spring adjustment screw out a good bit and drove the car to make it open. Mine has been fine since. Im not saying go on a journey away from home try to stay close to your house just in case u run into another problem. After it opens you should have an issue with the idle reset the bov adjustment so it wont leak and you should be set.

[bersh240]

okay. seriously. run no bov. problem solved.
idc how many people go "zomg!! you cant do that! your turbos gona explode!!!!"
its not going to unless its already on its way out.

if you really want it dont t off the wastegate line. just find a vac source behind the tb and run a line over to the bov.
but sounds like you have a sketchy bov anyway. so i highly recomend just tossing it...