I put a "supercharger" (soft) spring in my turbosmart to stop it. The springs that come in them are WAY WAY stiffer than needed because they have to allow for tools who have ****ty intercoolers with massive pressure drops across their intercoolers with the BOV on the hot side. If you have your BOV on the cold (throttle) side of the intercooler like U should, U can run a very soft spring without leakage because no matter how much boost u run, the same boost is also pushing down on the plunger PLUS the spring pressure.

And surge/flutter on lift-off is 100% HARMLESS. It's only surge on full throttle that is a serious problem.

 

First off, thanks for that great information It's definitely on the throttle side. Where can I find a softer spring like you mentioned?

And I realize its not hurting anything, but sometimes its dangerous to jerk around that much on icy roads, not to mention unpredictable.

 

I'm having this EXACT problem with my 05 stage 2 VF39, with TXS FMIC + BOV.
The previous owner had 4 washers installed in the BOV, so I took them out and it helped out a decent amount, but it still jerks the car like the OP mentioned. So I do believe an even softer spring will help even more and hopefully eliminate it, even tho its harmless I just hate the jerking. It literally forces me to drive with a heavy foot everywhere.

 

Yeah im going to try and loosen the nut a little but will replace the spring if need be

 

Any turbosmart dealer should be able to get the supercharger spring. i run the supercharger spring with the lid on the bov screwed down to full tight so there's less volume above the plunger, further reducing 'bov lag'

 

Thought I would update:

Have tried a few things: such as loosening to fully counter-clockwise (red line just starting to show) and still getting compressor surge. Idle is still a bit shaky.

I disassembled the BOV and checked for blockages, found none. I checked the vacuum hose when the car was running and it hissed as it should have, no blockage there.

However, the piston and cylinder are in need of some TLC, aka uni-glide. So prior to replacing a spring, I am going to lube them up with the oil that Turbosmart recommends and see if allowing the BOV to operate more smoothly mechanically will lessen or stop the compressor surge. Otherwise its new spring time. I figured it doesnt hurt to properly maintain my BOV on top of getting a softer spring, and if getting the $16 lubricant will save me money on the spring, then why not

 

I am getting similar surge issues at around the same RPM range with only like 7 PSI boost it starts surging with throttle pedal about 25% down. My BOV is Greddy RS with recirc plumbing. Did the lube help or did you need a softer spring?

 

I just tonight was able to lube up the cylinder/piston. Its zero degrees. Tomorrow night I will post back with any changes. When I was under the hood today removing the BOV, I found that the oem recirc hose had bent/kinked going around a fuel line, so it could be either the spring, the lube, or the kink thats causing the issue.

Should be sorted out by tomorrow night regardless.

Surging when pressing the throttle is much worse than what I am getting, which is surge upon lift - which I am learning is commonplace in cars with upgraded turbos.

You need to revert to the stock BPV, otherwise youll blow your turbo apart.

 

nah a bov with a soft spring WILL fix a part-throttle surge issue.

 

Provided it's a bov/recirc and is installed on the cold side correct? (I understand you're talking about the user above me).

Surge on throttle is definitely no good, I actually felt lucky it was only when lifting the throttle

 

It's plumbed for Recirc and installed on the driver side front of the TMIC

 

Ideally, you want NO surge at all... especially under throttle. Whats the status on the Turbosmart? Have you finicked with the different settings? Did this start out of nowhere? I know Brentuning can tune very well , and i'd say that he'd catch it when he was doing the roadtune/dynotune.

 

I havent driven the car yet today, since I don't drive it to work. I will update when I take the car to Moore Performance tonight. As far as adjustment goes, I have loosened it until the red line started to show with no decrease in compressor surge.

This has happened as soon as I drove the car on the highway after purchasing it, so I imagine it has always been the case. There is no surge if the boost is over 5-6 psi though. However, when I drive I often dont see more than 5-6psi when commuting around town, so it makes the drive very uncomfortable and unsteady when the compressor surge makes the car buck at highway speeds.

 

surge on FULL throttle is bad. Surge on 25% throttle is a good thing to get rid of but not that bad.

 

Okay update:

so it could be either the spring, the lube, or the kink thats causing the issue.

I have not yet replaced the spring.

I have lubed the cylinder and piston and saw a marginal (lets say 10-15%) decrease in surging.

Last night while at Moore Performance they were able to move the recirc tubing around and attach a clamp to prevent the hose from kinking. Saw an additional 10-15% less surging.

Overall, this leaves me with about 30% or so less surging, which is enough to make it acceptable.

However, last night when doing a pressure test, it was found that there is a leak on the BOV coming up out of the piston. Apparently the BOV had never been serviced and with the piston being aluminum, has developed some gouges/grooves with wear over time and will need rebuilt, not a big issue. I will call Turbosmart monday and ask about my options, and kill two birds with one stone by ordering a much softer spring as well.

 

That's good, I don't know about the Turbosmart but my Greddy RS has two springs inside and I just removed the weaker of the two springs instead of ordering a new spring. Unfortunately I lost a couple of the hex bolts that held the BOV together in my engine bay somewhere so now I have to get more, , oh well.

 

My STI runs the about the same way. I have a short drive to work and seldom reach 0 on the boost gauge so it isn't a problem.

 

Update: new issue:

So I was having this issue with my Tial QR recirc BPV. I had too stiff of a spring, and i had a bit of compressor surge every time I lifted the throttle, such as a normal gear change or just a bit of throttle input in gear. But digging deeper into the boost it would recirc like normal with no compressor surge.

I had the pink Tial QR spring: http://www.tialmedia.com/documents/w3_tial_bovq_sp.pdf

Since my QR is attached to the cold side of my Perrin FMIC piping, I thought I would go for the softest spring so it could recirc all it wants. So I purchased the black spring. $40 later, I install it and its fantastic!! No more surge on throttle lift, just a pleasant whoosh every time I change gear regardless of throttle input.

Enter: the road trip. Yesterday I put about 400 highway miles on my car. I was on the highway cruising in sixth and gave it the beans for a sec. Upon exceeding 24psi (I have a FP 20g 3" inlet 8cm hotside rebuilt by blouch a few months ago) I get massive amounts of compressor surge and bucking. This happens only in 5th and 6th gear.

Could this just be simply too much boost for the turbo to exhaust out? If so, is it related to my new super squishy spring in the Tial QR BPV?

I used my AP to monitor the following parameters while recreating this situation in 6th gear:
Boost: Upon hitting 24.5psi, the surging/bucking began, I did not keep the accelerator pressed down once this began, as I am worried about blowing the turbo. But 24.5psi what what it hit before I had to lift off.
AFR: dead solid 11.0 AFR with the throttle buried until I hit that surging/bucking in 6th. This is what my car has always run since the recent tune.
IDC: in sixth, it peaked at approximately 85% before I had to lift off due to the surging.
Wastegate duty cycle: I was so sure this was the issue, but lo and behold, it only hits 84% before the surging/bucking begins. For reference, a WOT 4th gear pull from 3k to 7200rpm results in a peak WGDC of 90%.

What on earth is wrong with my car!

 

I have an 06 STI as well and had a 20G on it for a while, then upgraded.
I have experienced and wondered about what you and others have described as compressor "flutter" when lifting off the gas. My thought is that this is due to the piston in the BPV oscillating back and forth against the spring. That's why a weaker spring helps. I think only BPVs that have some sort of damping on the piston such as the stock BPV or the HKS (I believe) will completely eliminate this.

Your new issue which appears to be truely compressor surge and will eventually damage the turbo if it continues. I don't believe its related to the weaker spring. I also don't know how to correct this. Maybe someone more knowledgeable can help.

 

I was told when experiencing the same thing that it was simply a Part Throttle Full Boost (PTFB) issue. I was advised to basically just drop another gear to pass so my RPM's match the amount of boost I receive. Apparently this is less likely to happen if you still have the wastegate Solenoid hooked up because it only allows certain amounts of boost at certain RPM ranges to keep this from happening.


Check this thread for a better explanation.
http://www.iwsti.com/forums/ecu-tuning-performance-electronics/211490-compressor-surge-log-data.html

 

I don't see boost controller on your mods list. Please tell me you aren't still running the OEM passive BCS.

In the meantime: try downshifting before "giving it the beans".

 

It has a prodrive EBCS.

And the issue isn't top gear, it's 5th as I will be using up to the top of 5th gear at the track where the back straight goes up to about 125-130mph. I'll be sorely disappointed if I can't "give it the beans" on the track.

 

That's the EBC I'm running (love mine). I fully understand the disappointment of not "giving it the beans" @ the track. Do you have the Prodrive connected to the intake or just vented to atmosphere? People say it didn't make a difference, but I doubt that. Prolly won't fix your issues, but ya never know. You have a big MAF sensor? What waste gate? Might need to go external with that setup.

 

I'm thinking external wastegate is the answer, its also what my tuner said. My 20g is on the stock IWG. I have a Big Maf intake, and my EBCS is connected to the vaccuum lines coming off the turbo and wastegate.

I think my IWG'd turbo cannot handle 24psi in 4th gear, because it runs nearly 26+ PSI in the top two gears as a result. I previously had a bit of a leak (crumbled header to uppipe gasket) during my dyno tune so I only went up to 21psi. After fixing the gasket, without a retune the fourth gear peak boost hits about 24.2psi. I datalogged and my tuner gave me an updated map, but it still hits 24psi in fourth. Going to talk to him about taking it down a couple notches until I am EWG.

 

I'm thinking external wastegate is the answer, its also what my tuner said. My 20g is on the stock IWG. I have a Big Maf intake, and my EBCS is connected to the vaccuum lines coming off the turbo and wastegate.

...and there is no line on the third port (atmosphere)? If I were you I'd run a vac line from that port to the intake first. Most people have your set up, and not mine. With an OEM MAF, the intake pressure is, for all practical purposes, atmospheric (+- < .1 psi). However, if you have a big MAF & a BOV, that MIGHT not be the case. If it didn't make a difference Prodrive wouldn't have put an intake port on their EBC.

Why did I run my intake vac line? +- .1 psi isn't within my spec tolerance. I don't know EXACTLY what I will do to my car in the future. I might get a big MAF or something.

If that doesn't help, then it's prolly EWG time. I have a dp with a blocked off EWG bung. I try to stay 3 steps ahead of myself.

I'm an engineer, not a tuner, so take this with a grain of salt & maybe confer with whomever does your tuning first.

ETA: Oh, and good luck. On your car & at the track.

 

its a BPV, its fully recirculating. I'm going to investigate a few things this weekend, including a possible boost leak also (post maf) that might be borking my tune.

 

Regardless of the type of BOV/BPV you have, a big MAF can cause problems you wouldn't normally have. That's why I suggested you try EBC intake hose first. It's only a $0.25 vac hose & 30 second install. When you've done everything you can think of & are just doing random things on the hope you will fix it, I always start with the cheap and easy stuff.

 

Had my tuner drop my boost target from 24psi to 21.5psi. It still hits over 22psi due to the cold weather but overall I am much happier with this new map. The power is flat and smooth (peak 22.5psi tapering to 19.9 at redline) and in top gear it no longer does that crappy compressor surge bit!