Would you rather have a properly running car or a fear of something that is nearer a myth? I had zero fear of compressor surge with my 11 psi spring and dual washers. I can send you some nice perfectly sized aluminum washers from McMaster Carr if you would rather go that method.

FI turbo issues
 

If the BOV is before the MAF you want a lighter spring so you get fastest reaction. The new location also requires a softer spring as its about 5 feet (vacuum line from the IM to the BOV) from the vacuum source. Anything more than 3 ft from the vacuum source and you want a step softer. With the new location there should be no issue with the MAF being open or closed.

There are no leaks. I pressure tested it up to 15psi. When the pipes were swapped I went over every couplers before the bumper went back on to ensure proper sealing at the beads.

Tuners input would be great :thumbsup:

The BOV went from here

https://scontent-b-dfw.xx.fbcdn.net/...52037494_n.jpg

to here

https://scontent-b-dfw.xx.fbcdn.net/...98248620_n.jpg


Some info from Tial

http://oi61.tinypic.com/t71jx0.jpg

I would think with the BOV being that far from the MAF sensor that yes you could run a spring that opens up at idle with no issues, but it doesn't appear to be the case according to @evo4g63 . I can't see the info from TiAL you posted since it is a tinypic. Can you link me to it on the Tial website? Here is their info on picking the right spring:

http://www.tialsport.com/documents/w3_tial_qqr_sp.pdf

FI turbo issues
 

On the original test car we tried 6, 8, and 10psi springs. The best reacting without any flutter was the 6. Same on this car is question. I'll find another link. Tial doesn't go into detail on the site for some reason

As I have mentioned offline the tune is the likely suspect based on what symptoms you have relayed to me. Mechanical issue is the least likely and as others have said the surging is not something to be worried about especially during little throttle blips or light load. Without datalogs or really any real information it's pure speculation. James I believe said the same thing I did when you first contacted me. It sounds like an injector scaling issue or perbaps something else in the tune that is a little off. I'm not usually so quick to suspect the tune but in this particular case it's something that needs evaluation. I will leave it up to the OP to disclose who is/was tuning it but really I feel you need to find someone else :thumbsup:

It is obvious that the 6 psi spring is going to react quicker than any of the others. That isn't in question. I mean it is ready to open up at idle with no issues so when you slam that throttle closed it will definitely open quicker. The question is whether or not its opening at higher vacuum levels is causing enough turbulance to upset the air flow across the MAF. It is an easy thing to verify by removing it from the equation and just removing the vacuum source from the BOV so it stays closed no matter what. If it makes no difference then it is clearly a tune issue.

FI turbo issues
 

The new location of the bov should have no effect on skewing maf readings. I think we need more tuner input honestly

I still haven't heard him mention whose tune he is currently running, but I agree that I still think it is a tune issue and not a BOV issue.

it seems he doesn't want to disclose. must be tony@fa20club ;) [just kidding]

I have been avoiding getting involved until now but... Since the OP is beating around the bush:


To the OP: You know you could just do what everyone has told you and moved on with the tuner filling your head with false info.

https://dl.dropboxusercontent.com/u/...54.23%20AM.png

If you note here you will see his car picking up negative fuel trims while in mixed injection mode. But once it goes port only (this is a very short period of time) you can see the fuel trims retracting. And during this time the AFR is just shifting lean and the engine is shutting off. This is a direct cause of issue from port injector latency mis-calibration. What is going on is the ecu is opening the injectors for what it expects is x# of ms, but due to latency of opening time it is not actually opening the duration it requested. The issue was in the 6g/s learning window. Which is why it was not affecting all other areas as that window would shift between DI and DI + Port from time to time. The reason you didn't have this issue with the first flash from your tuner is because he was maxing out the fuel trim on the rich scale. You were running well below 11AFR and so when the ecu attempted to pull fueling it was maxing out the short term trims (since your tuner doesn't use long term trims) and the ecu was not allowed to pull any more fueling out. This would run a longer than desired injector port time which was actually closer to correct due to the fact the latencies are set to a smaller value than they should be. If you still want to beat around the bush go install your stock injectors and see what happens. Hell a stock rom would probably even work considering the maf size for a simple throttle blip as it would have long term trims, and much better port latency times.

Sure the MAF can be skewed with the blow off valve but there are a number of resolutions to that such as hacking the MAF table, speed density, adjusting overrun MAF, custom tables based off misc inputs. I tried to help you out in person at JDL and told you that it takes a bit to dial in injectors but yo insisted on using your current tuner. Here you are going in a full circle to find out you are having the same issue from the start: a tuner issue.

I can tell you with 95+% certainty that this is a tune issue. The symptoms you describe are something that I fix for customers on a weekly basis. Idle dipping, near stalling when you come to a stop. It's almost always in the tune, and it's due to extremely high fueling error and LTFT being turned off in closed loop. The only other thing that I've ever seen cause this is when the vacuum lines pop under the manifold, but usually then it's way more exaggerated, and the car will stall all the time (not to mention you can hear it clear as day).

You just need a new tune. This has nothing at all to do with a BOV or your MAF. I'd bet my paycheck on it.

EDIT: @nelsmar pretty much got it, and it's really pretty simple: latency is wrong so you have massive fueling error on the low end port side. without LTFT there to expand the compensation range (ltft and stft stack, so giving up ltft halves the operable correction range) and stabilize things the car simply can't correct itself in time to keep from stalling when it falls back to port-only injection.

This is why port and direct injection balancing is so important to drivability, and why it's so important that fueling error be as low as possible in every case. Even if you had LTFT turned on, that doesn't necessarily solve the problem. Trims have no knowledge of injection ratio. The common case is this (when LTFT is left on in closed loop):

- Car starts and idles on ports only.. builds up a massive trim (often because latency is wrong)
- You drive away... car warms up while you're driving
- You pull up to a stop, car is now warm and attempting to idle on DI only
- Car stalls or idle dips because the error on the port side (for which the low bucket LTFT was calculated when you were idling there warming up before) is wildly different than the error on the DI side.

In other words, the car has two independent 'fueling error amounts' that it needs to compensate for with trims, but only one mechanism (set of trims) with which to do it. It never says 'oh I'm on DI now... i need to trim differently than a while ago when I was in the same maf bucket but was on port only'. This is why it is absolutely crucial that you have extremely low trims independently on both the port and di side of the equation. they have to both be minimal or else you'll have wild afr swings when the injection ratio changes that cause issues like you describe.

Also as for tuners... You already have a long list of people to go to.

Just to name a few:

HRI
Delicious
Moto East
JR
Evasive

And others.

And to the others viewing this thread I am not the tuner involved that the OP is talking about. I just tried to offer a hand when I was at JDL one evening.

Sent from my IBrick

This. I had the same exact issues with my tune when I sold the car, and I am not affraid to say that it was an FA20Club tune. I knew that the BOV was not causing the issue because I had already eliminated it as a possible cause. I informed Toni of the issue multiple times since my first drive home from being "tuned" meaning 10 flashes on the dyno and zero time tuning on the street.