General Please help me fix my compressor surge!

[curt-s]

Yeah, the Q and the BV50 are practically identical except some body changes. Same springs, but they both have O rings to seal. I just could have sworn I saw the piston drop down a bit just before it started chirping.
That 45 deg coupler doesn't look to be any more restrictive than a 14b OEM piece and your boost is below stock level even for that..
But at this point anything is game.
Maybe you'll find half a sock in there.

Next I would be looking for restrictions in all the intercooler pipes, especially the lower ones to the IC.

The turbo even at 14lb/min may be trying to force more air than is being allowed through. Is there something blocking the IC inlet

 

[Mello]

I always use silicone based lubes with o-rings, either silicone spray, dielectric grease, or caliper grease (all these are silicone types). Truthfully I use silicone based on anything rubber & avoid petroleum based lubes.

 

[We're on Boost]

Next I would be looking for restrictions in all the intercooler pipes, especially the lower ones to the IC.

The turbo even at 14lb/min may be trying to force more air than is being allowed through. Is there something blocking the IC inlet

Maybe the restriction is just the throttle butterfly. It's only open about 25% when this is happening.
This is happening at about 4000 rpm in the 2nd log (the one called wastegate) and it happens I figure at ~19 seconds in the log, ~20 seconds in the video ( they are synced pretty close, only about 1 sec off) where throttle reduces from 26% to 23%. That's when it starts to flutter. The BoostPSI drops from 2psi to 0psi, and then it just keeps dropping for about the next 1 second, to -9 inHg. Then half a second after that is lifting to shift.
The BoostPSI we see is the intake manifold pressure. We don't know what pressure is between the turbo and the throttle body but I think it could be well over 2psi at 4000 rpm and ~25% throttle. Doesn't seem like it would be enough to cause turbo surge but maybe enough to push past the BOV and make that noise?

 

[silentsnow31802]

I have a "Stuff" folder too. It's got a lot of Stuff in it. Yeesh it has 10,370 files. 10 GB.
You know, some types of o-ring lube are made for assemblies that move very slowly or don't move at all, like the o-ring on the Weld Flange.
I use Dow Corning Silicone Compound 111 for things like that.
But 111 Compound is very viscous. I don't think I'd use it on something that has to move fast and moves a lot like this piston, because it would probably drag too much.
That's why I think it would be good to know what Tial says to use on it.

I did email Tial tech support twice in 2016 and got pretty good answers back.
At the time it was Tech Support <[email protected]>

10GB!? You must have all the manuals saved!
Speaking of stuff.... Here is my lube tube.
Stuff is pretty thick. I didnt put any on the BOV.

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Yeah, the Q and the BV50 are practically identical except some body changes. Same springs, but they both have O rings to seal. I just could have sworn I saw the piston drop down a bit just before it started chirping.
That 45 deg coupler doesn't look to be any more restrictive than a 14b OEM piece and your boost is below stock level even for that..
But at this point anything is game.
Maybe you'll find half a sock in there.

Next I would be looking for restrictions in all the intercooler pipes, especially the lower ones to the IC.

The turbo even at 14lb/min may be trying to force more air than is being allowed through. Is there something blocking the IC inlet

I dont think there is a flow restriction as I can get plenty of flow if I just floor it.
I did take the filer and silicone 45 off and found no socks! I wussed out and put it back on before taking the car out again. There was a lot of tree particles floating around the car and I didnt want to risk the turbo eating any of it. I got a new video with better lighting though! Also attached a log to go with it.

Maybe the restriction is just the throttle butterfly. It's only open about 25% when this is happening.
This is happening at about 4000 rpm in the 2nd log (the one called wastegate) and it happens I figure at ~19 seconds in the log, ~20 seconds in the video ( they are synced pretty close, only about 1 sec off) where throttle reduces from 26% to 23%. That's when it starts to flutter. The BoostPSI drops from 2psi to 0psi, and then it just keeps dropping for about the next 1 second, to -9 inHg. Then half a second after that is lifting to shift.
The BoostPSI we see is the intake manifold pressure. We don't know what pressure is between the turbo and the throttle body but I think it could be well over 2psi at 4000 rpm and ~25% throttle. Doesn't seem like it would be enough to cause turbo surge but maybe enough to push past the BOV and make that noise?

This was my thought actually. I have no idea how that could be possible though. Its almost like the turbo makes more flow than the throttle position is letting into the engine. Which is why its fine at WOT but not partial throttle when boost starts to build.

I can try and plumb the boost gauge into the piping somehow. I cannot log that though. My gauge isnt hooked up to anything but itself for a display to the driver.


But here is the latest video and attached is a log to match.
I put the Black softer wastegate spring in it and changed the lighting.
Something to note, the blow off sound is now more of a woosh than a fluttering noise. The surge still happens. As Were on Boost stated I did notice the boost gauge drop to 0 when the fluttering started in 3rd gear.

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The BOV is now open at idle.

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Diaphram looks to be in good condition.

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I did not need to tuck it in. There was plenty of clearance.

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Here is my pimptastic camera setup.

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[We're on Boost]

Here is my pimptastic camera setup.

That looks really good! The camera with flashlight strapped on. Is it a gopro? What is model is the mounting bracket you are holding it with?
Going to look at all this stuff more later.

 

[We're on Boost]

But here is the latest video and attached is a log to match.

Well it's going into flutter at about the same conditions we had in the Feb 14 logs.

From mild acceleration with 2 to 5 psi of boost and about 27% throttle and 10 to 12 lbs/min airflow, it starts fluttering right after backing off 1% on the throttle, at ~4000 rpm or a little higher. Then boost and airflow drop off.

We have good light on the BOV ports now, that piston ring land is clear to see, and the piston doesn't seem to pull down at all during the flutter. If it does pull down it must be really small like 15 thou or so. I don't know if that o-ring actually seats on something like a chamfer when it's closed, or if it just seals OD to cylinder wall.

So going from the plain spring to the black spring didn't change the flutter any that I can tell.

The bench test opening vacuum levels are different by about 8 inHg.
-20.4 Plain, -12.2 Black. (see pdf chart below)
Quite a bit different, but I only see that difference in how it opens when you lift off to shift or at idle. I don't see difference in the flutter.

I think it would be good if you could hook up your human readable boost gauge to the turbo outlet like where your wastegate line goes, maybe a T there, or to the intercooler piping somewhere. Because maybe the pressure in the piping is more than we think.

Just going by the logged BoostPSI number of 2 to 5psi, and the airflow number of 10 to 12 lbs/min, I don't see why the compressor would be surging. Those numbers put it near the middle of the lower part of the 16g compressor map. 10 to 12 lbs/min, if you wrangle that to cubic meters per second like I see on the Mitsu 16g compressor map, that would be about .06 to .075 cubic meters/sec and that should be ok up to 1.8 pressure ratio which would be ~11 psi of boost.

So if you have more than 11 psi gauge pressure at the compressor outlet just before the flutter starts, that could be it.
Mitsu big 16g compressor map and .06 M3/s to 9.52 lbs/min conversion for air at standard conditions(approx):

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I noticed by looking at old FP compressor maps for the 20g and 18g that Robert Young has a slightly different conversion between cubic meters per second and pounds per minute. So if anybody knows why that is I'd like to know.

Tial BOV test chart pdf:

 

[silentsnow31802]

That looks really good! The camera with flashlight strapped on. Is it a gopro? What is model is the mounting bracket you are holding it with?
Going to look at all this stuff more later.

It is indeed a gopro. The mount is just some random pieces I had cobbled together. The arm is from the suction cup https://gopro.com/en/us/shop/mounts-accessories/suction-cup/AUCMT-302.html I just threaded the center hole onto a stud for the boost pipe. It just happened to fit perfect.

Well it's going into flutter at about the same conditions we had in the Feb 14 logs.

From mild acceleration with 2 to 5 psi of boost and about 27% throttle and 10 to 12 lbs/min airflow, it starts fluttering right after backing off 1% on the throttle, at ~4000 rpm or a little higher. Then boost and airflow drop off.

We have good light on the BOV ports now, that piston ring land is clear to see, and the piston doesn't seem to pull down at all during the flutter. If it does pull down it must be really small like 15 thou or so. I don't know if that o-ring actually seats on something like a chamfer when it's closed, or if it just seals OD to cylinder wall.

So going from the plain spring to the black spring didn't change the flutter any that I can tell.

The bench test opening vacuum levels are different by about 8 inHg.
-20.4 Plain, -12.2 Black. (see pdf chart below)
Quite a bit different, but I only see that difference in how it opens when you lift off to shift or at idle. I don't see difference in the flutter.

I think it would be good if you could hook up your human readable boost gauge to the turbo outlet like where your wastegate line goes, maybe a T there, or to the intercooler piping somewhere. Because maybe the pressure in the piping is more than we think.

Just going by the logged BoostPSI number of 2 to 5psi, and the airflow number of 10 to 12 lbs/min, I don't see why the compressor would be surging. Those numbers put it near the middle of the lower part of the 16g compressor map. 10 to 12 lbs/min, if you wrangle that to cubic meters per second like I see on the Mitsu 16g compressor map, that would be about .06 to .075 cubic meters/sec and that should be ok up to 1.8 pressure ratio which would be ~11 psi of boost.

So if you have more than 11 psi gauge pressure at the compressor outlet just before the flutter starts, that could be it.
Mitsu big 16g compressor map and .06 M3/s to 9.52 lbs/min conversion for air at standard conditions(approx):

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I noticed by looking at old FP compressor maps for the 20g and 18g that Robert Young has a slightly different conversion between cubic meters per second and pounds per minute. So if anybody knows why that is I'd like to know.

Tial BOV test chart pdf:

Yes the fluttering doesnt seem to have changed. Even with the spring change.
If I remember right the O ring does sit on a chamfer. It looks to me that it would seal fine.

Here is the video with the boost gauge hooked up to the J-pipe.

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If I have lined up the video and log right. Log at the 20.7 second mark and the video at the 21 second mark, it looks to be measuring about 5psi in the intake and 11psi in the J-Pipe. Thats a big difference.

 

[We're on Boost]

it looks to be measuring about 5psi in the intake and 11psi in the J-Pipe. Thats a big difference.

That video of the gauge is very interesting. Yeah I see the gauge hitting 11 and even 12 psi.
At that low airflow rate of about 12 or 13 lbs/min, the conditions are very close to going off the left side of the compressor map - which would be surge. There are approximations in trying to look at it this way so it's a little vague. But I'd say it's actually possible that the compressor is surging. And maybe it's also possible that the high pressure in the intercooler pipes is just enough to push the BOV into leaking with that oscillating fluttery stuff. But if that 2nd idea is it, I would think there would be a noticeable difference between the 2 springs that you've tried, and I would think we'd see the piston coming down a little bit in the BOV videos when it flutters.

 

[Justin DuBois]

It is indeed a gopro. The mount is just some random pieces I had cobbled together. The arm is from the suction cup https://gopro.com/en/us/shop/mounts-accessories/suction-cup/AUCMT-302.html I just threaded the center hole onto a stud for the boost pipe. It just happened to fit perfect.



Yes the fluttering doesnt seem to have changed. Even with the spring change.
If I remember right the O ring does sit on a chamfer. It looks to me that it would seal fine.

Here is the video with the boost gauge hooked up to the J-pipe.

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If I have lined up the video and log right. Log at the 20.7 second mark and the video at the 21 second mark, it looks to be measuring about 5psi in the intake and 11psi in the J-Pipe. Thats a big difference.

Don't you love how the capture rate on the camera and the frequency of LED refresh on the gauges make it so inconvenient to read? PITA. This was an issue way back before data capture was common.

 

[Talon43219]

How big is your exhaust? I had the same compressor surge when I would merge on to the freeway or with part throttle pulls. It turned out to be a restriction in my exhaust system that caused my flutter.

 

[Justin DuBois]

How big is your exhaust? I had the same compressor surge when I would merge on to the freeway or with part throttle pulls. It turned out to be a restriction in my exhaust system that caused my flutter.

good question

 

[curt-s]

k bov valve is definitely not opening in that last well-lit video. I love that mounting, very creative

data log shows 1/2 the intake pressure the gauge is reporting, as you said. 5psi in the manifold via your P port, yet 11psi off the J pipe. that's a rather large pressure differential..

also an oddity is your wideband is reporting AFRs that are extremely delayed from your commanded AFRatioEst after transitioning to open loop. it takes nearly two seconds after entering open loop in second and third gears for it to even start moving when that should be in the realm of hundreds of milliseconds at nearly 4k rpm. it also oddly lines up with your drop in PSI when it finally does decide to start moving towards the commanded AFR. as soon as you go open loop that AFR should drop like a stone unless your WB is really, really slow. if that's the case, I wouldn't even tune with it.

my wonder is, is this a case where the turbine has to spin extraordinarily fast just to produce even this low boost level? compressor isn't damaged? have you given your compressor wheel a check recently? in/out, side/side play, general condition.


weird question, you're not using the sensor ground on the ECU for your WB and MAP sensors, are you? not saying it's related but just asking.

 

[We're on Boost]

Holy cats I think I messed up in post #64.
Here is what it should be, I think. Starting with the 3-port picture again:

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Basically, 0% duty cycle ("inactive") completely connects the lower port to the "common" port which allows maximum air pressure through to the actuator canister.
That air pressure pushes against the spring. (Opposite direction)
Spring is trying to close the wastegate. Air pressure in the canister is trying to open the wastegate. So more air pressure in the canister is minimum boost.
You get maximum air pressure in the canister from 0% duty cycle. So 0% duty cycle is minimum boost. 100% duty cycle is maximum boost.

This is actually good. Because I think you can use this to get some help from the boost controller settings in the Boost tab.

 

[curt-s]

5psi at the intake manifold (assuming that's correct even though it should be closer to J-pipe) even with 25% throttle and 4k rpm, the engine should be able to eat that air with little problem.
that is, if that truely is the correct reading on pressure.

wouldn't a restrictive exhaust slow down exhaust flow thus doing the same to the turbine? that would produce a lower boost level overall, so you wouldn't be jamming more air into the engine than it can take at a specific RPM.

 

[silentsnow31802]

That video of the gauge is very interesting. Yeah I see the gauge hitting 11 and even 12 psi.
At that low airflow rate of about 12 or 13 lbs/min, the conditions are very close to going off the left side of the compressor map - which would be surge. There are approximations in trying to look at it this way so it's a little vague. But I'd say it's actually possible that the compressor is surging. And maybe it's also possible that the high pressure in the intercooler pipes is just enough to push the BOV into leaking with that oscillating fluttery stuff. But if that 2nd idea is it, I would think there would be a noticeable difference between the 2 springs that you've tried, and I would think we'd see the piston coming down a little bit in the BOV videos when it flutters.

Yea I think thats my issue. Im making more air than the engine is able to take in because the throttle plate isnt open enough. Doesnt make sense to me though. How do others not have this issue when upsizing their turbos or get more efficient ones that make boost sooner in the RPM range?

Don't you love how the capture rate on the camera and the frequency of LED refresh on the gauges make it so inconvenient to read? PITA. This was an issue way back before data capture was common.

Yes this is quite annoying . Trying to pause the video to get a reading on the gauge to compare was a pain.

How big is your exhaust? I had the same compressor surge when I would merge on to the freeway or with part throttle pulls. It turned out to be a restriction in my exhaust system that caused my flutter.

Its not small.... Ive never measured but its a typical large exhaust. Maybe 3" I would say. All the way from the turbo. None of it is stock.

k bov valve is definitely not opening in that last well-lit video. I love that mounting, very creative

data log shows 1/2 the intake pressure the gauge is reporting, as you said. 5psi in the manifold via your P port, yet 11psi off the J pipe. that's a rather large pressure differential..

also an oddity is your wideband is reporting AFRs that are extremely delayed from your commanded AFRatioEst after transitioning to open loop. it takes nearly two seconds after entering open loop in second and third gears for it to even start moving when that should be in the realm of hundreds of milliseconds at nearly 4k rpm. it also oddly lines up with your drop in PSI when it finally does decide to start moving towards the commanded AFR. as soon as you go open loop that AFR should drop like a stone unless your WB is really, really slow. if that's the case, I wouldn't even tune with it.

my wonder is, is this a case where the turbine has to spin extraordinarily fast just to produce even this low boost level? compressor isn't damaged? have you given your compressor wheel a check recently? in/out, side/side play, general condition.


weird question, you're not using the sensor ground on the ECU for your WB and MAP sensors, are you? not saying it's related but just asking.

If the wideband is delayed thats news to me. Ill have to look more into that one somehow.

The turbo is fine. It was recently rebuilt by Justin Whitesell. Has maybe 1 tank of fuel through it. I had the intake pipe off a few days ago and checked it and everything still looked fine. Come to think of it he did modify the turbos hot side. It has a larger turbine wheel at 70mm compared to a big 16g's 68mm.

Here are the notes on the turbo I wrote down...
Current Modified EVO 16G - 48/70mm
Garrett T04B 70mm Turbine
MHI Turbine Shaft
Evo3 16G 7CM Turbine Housing
Small 16G Compressor Housing
Clipped

The Wideband is using a chassis ground and the MAP sensor is plugged into ECMLink speed density cable.

Holy cats I think I messed up in post #64.
Here is what it should be, I think. Starting with the 3-port picture again:

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Basically, 0% duty cycle ("inactive") completely connects the lower port to the "common" port which allows maximum air pressure through to the actuator canister.
That air pressure pushes against the spring. (Opposite direction)
Spring is trying to close the wastegate. Air pressure in the canister is trying to open the wastegate. So more air pressure in the canister is minimum boost.
You get maximum air pressure in the canister from 0% duty cycle. So 0% duty cycle is minimum boost. 100% duty cycle is maximum boost.

This is actually good. Because I think you can use this to get some help from the boost controller settings in the Boost tab.

If I can somehow tune around this that would work for me. I would have to mess with it after my tuner is done as I dont want to mess with what he is doing. It might be a while though because we get logs back and forth 1 or 2 times a month.

What doesn't make sense about any of this is it's all being reported as a part throttle problem. Not 100% WOT. Would like to see a log of that.

I know right!? Thats whats bothering me too. Its not even when the turbo is working hard pushing a lot of air. Its just when im trying to cruise which is why its VERY annoying. Makes the car pretty crap to drive normally.

 

[We're on Boost]

wouldn't a restrictive exhaust slow down exhaust flow thus doing the same to the turbine? that would produce a lower boost level overall, so you wouldn't be jamming more air into the engine than it can take at a specific RPM.

That's what I think too. It would dial down the turbo.

 

[We're on Boost]

This is actually good. Because I think you can use this to get some help from the boost controller settings in the Boost tab.

In all of the logs so far, the Boost setting "And then 100% below" has been set to a high psi number, usually 17.92psi. So at low manifold pressures like where you are getting this flutter, the turbo is getting 100% duty cycle which is maximum boost. So the turbo is trying for max output and your throttle is not even 1/3 of the way open and that results in the big difference between piping pressure and manifold pressure.

You should see what happens when you set the duty cycle to 0% in that region instead of 100%.

To see if this is even a correct theory, I think the easiest way is to set the duty cycle to 0% everywhere all the time, and see what happens. Minimum boost all the time.

It would be cool if you could set the duty cycle to 0% just by unchecking "Enable boost control". But after reading the ? Help, I don't think it works that way (it says unchecking that box typically locks duty cycle to 100%).

I think you could make duty cycle 0% all the time without changing any of the values in the table. You'd use "Lock at 0% below". Put a high psi number in there, higher than you would ever go. 30 or 35 psi. I don't think it will even matter what number you have in the "And then 100% below". Because the Help says it won't use the 100% below number until it has exceeded the 0% below number first. Well make it so you never exceed the 0% below number.

Obviously you don't want to leave it at 0% forever but it should help us figure out a way to go. We are getting WGSDuty in the logs, so we'll be able to see if we're getting 0% duty. And if you keep the boost gauge connected to the J-pipe for a while we'll be able to watch the pressure differential between pipes and intake manifold.

So basically you could try this out by changing just the one number "Lock at 0% below". Don't change anything else. Easy to do and easy to undo.

 

[curt-s]

I've never used that field but I myself use 100% duty in the table until about 3000rpm. It keeps the wastegate pinned shut until I want it to start cracking open at my target full spool RPM.
Unfortunately, in fifth gear, this can cause you to run 100% duty at an RPM where you'll be above your target. Since we don't get a 4th and 5th gear row, this can cause massive overshoots. Hell, I made my B16g surge at 2000rpm at 23psi in fifth gear, because only half the runners were open due to the RPM trigger settings for my cyclone manifold.
Using this little setting there can help where you know you want 100% until a minimum pressure, and then run a specific duty after that.
You're still possibly hosed for 5th gear in low RPM though because your duty then may not match what it is in third. I don't know, I plan on testing this and setting it to lock at 100% below 18psi myself.

The only thing, though, is changes to wastegate pressure are not instantaneous. There's a large dampening effect going on with that side due to exhaust flow path changes. I don't think the problem lies with the wastegate, especially if he can reproduce the problem with the J-pipe tied directly to the WG.

 

[silentsnow31802]

Okay I set the "Lock at 0% below" value to 30. It seems to be working off wastegate pressure now. Here is the log and video just like before.
I did not hear the turbo surge this time. Probably because of the low boost levels.
I think were heading in the right direction though!

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[We're on Boost]

Good job with the video.
Ok the driving style is similar to before, that is, throttle about 27%, rpm going to a little over 4000, airflow getting up to 10 or 11 lbs/min. One thing different I think is that this time you aren't backing off gradually before the shift, or not as much anyway. And that's usually when the flutter started previously.

Pressure in the pipe is getting up to 9psi, only about 2 psi less than before, but it seems to be enough lower to prevent the flutter.

It did keep duty cycle at 0% all the way through.

I think the next thing to do is figure out how to make it ignore both of the fields "0% below" and "100% below" so it uses only the Base Duty Cycle table and nothing else.
I think a way to do that is to set the "0% below" and "100% below" fields both to 0.
Or if that doesn't work, you could try setting both of those fields to -29.92 inHg.

I'm thinking both 0 because zeros are the default number in those blanks when this page has never been used. (Like mine, because I've never used the boost control in ECMlink). BTW I read the Help and all the boost control wiki pages looking for how to make it ignore those 2 fields and I couldn't find it! Sheesh.

If you get it to set duty cycle solely by the Base Duty Cycle table, then the duty cycle will be somewhere between 60% and 75% with the values you have in there now.
This might be enough duty cycle to make it flutter again, but try it out to see if it does follow the Base Duty Cycle table only, and to see if flutter happens.

If it does follow the Base Duty Cycle table only, but the flutter comes back, then the next thing to try would be to set all the table values to some low number like 20 or even 0 in all the columns from 2000 to 4000 rpm. Leave the current numbers in there for 4500 rpm and up.

Then test drive that. It might actually work to prevent the flutter. I think the loss in performance could be less than you'd expect because the "spring pressure" might be 14 or 15 psi. I guess we don't know what it is.

Seems pretty clear that controlling boost solely by rpm isn't going to be the greatest possible way you could ever think of. Might be better if we could also control it with throttle position!

If this general way of doing it can be made to work, it is still a work-around for some basic physical thing that isn't as wonderful as it should be. But it might be good enough for a while until something better comes along.

When you want to change the Base Duty Cycle table back to the values that your tuner had in there, just have one of your older logs up at the same time, copy the table from it, and paste it into the one you want to change. The copy and paste is in the right click menu, and a bunch of other useful things too, like set values to 0, and set values to ... (number of your choice). If you haven't used those right click things much yet, practice for a while without being "Connected". Shift-selecting a rectangular region also works, for highlighting the area you want.
Here I got a region highlighted and then used right click "Zero values" to set the whole region to 0:

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[silentsnow31802]

Good job with the video.
Ok the driving style is similar to before, that is, throttle about 27%, rpm going to a little over 4000, airflow getting up to 10 or 11 lbs/min. One thing different I think is that this time you aren't backing off gradually before the shift, or not as much anyway. And that's usually when the flutter started previously.

Pressure in the pipe is getting up to 9psi, only about 2 psi less than before, but it seems to be enough lower to prevent the flutter.

It did keep duty cycle at 0% all the way through.

I think the next thing to do is figure out how to make it ignore both of the fields "0% below" and "100% below" so it uses only the Base Duty Cycle table and nothing else.
I think a way to do that is to set the "0% below" and "100% below" fields both to 0.
Or if that doesn't work, you could try setting both of those fields to -29.92 inHg.

I'm thinking both 0 because zeros are the default number in those blanks when this page has never been used. (Like mine, because I've never used the boost control in ECMlink). BTW I read the Help and all the boost control wiki pages looking for how to make it ignore those 2 fields and I couldn't find it! Sheesh.

If you get it to set duty cycle solely by the Base Duty Cycle table, then the duty cycle will be somewhere between 60% and 75% with the values you have in there now.
This might be enough duty cycle to make it flutter again, but try it out to see if it does follow the Base Duty Cycle table only, and to see if flutter happens.

If it does follow the Base Duty Cycle table only, but the flutter comes back, then the next thing to try would be to set all the table values to some low number like 20 or even 0 in all the columns from 2000 to 4000 rpm. Leave the current numbers in there for 4500 rpm and up.

Then test drive that. It might actually work to prevent the flutter. I think the loss in performance could be less than you'd expect because the "spring pressure" might be 14 or 15 psi. I guess we don't know what it is.

Seems pretty clear that controlling boost solely by rpm isn't going to be the greatest possible way you could ever think of. Would be better if we could also control it with throttle position!

If this general way of doing it can be made to work, it is still a work-around for some basic physical thing that isn't as wonderful as it should be. But it might be good enough for a while until something better comes along.

When you want to change the Base Duty Cycle table back to the values that your tuner had in there, just have one of your older logs up at the same time, copy the table from it, and paste it into the one you want to change. The copy and paste is in the right click menu, and a bunch of other useful things too, like set values to 0, and set values to ... (number of your choice). If you haven't used those right click things much yet, practice for a while without being "Connected". Shift-selecting a rectangular region also works, for highlighting the area you want.
Here I got a region highlighted and then used right click "Zero values" to set the whole region to 0:

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I did not back off because the car never started to flutter. I backed off when the flutter started because its quite violent in the car. Cant be good for my motor mounts or transmission.

I will set both those fields to 0 in hopes it does not use them. I think your right since those are the default values. Ill do that and take a log and report what happens.

I will also try a drive with the 200-400 set to 0 just so I have more information to give. The wastegate is from the stock turbo on the car so it should be stock non EVO pressure. I think thats 9psi?

Im okay with a small loss in performance if I gain drivability. Its really bad as is. Makes me not want to drive it.

I have all the files the tuner ever sent so ill make sure its as he set it before i continue with him. I dont want to send him something I modified .

Really appreciate all the help here. This surging was driving me crazy.
The last time I took the car out with the Lock at 0% below set to 30 was the best the cars felt drivability wise since I got it. It was pretty slow though....

 

[We're on Boost]

I did not back off because the car never started to flutter. I backed off when the flutter started because its quite violent in the car.

Oh ok that's good to know, that the flutter starts before any backing off of the throttle. I thought it was kind of weird that a back-off of only 1 or 2% would start it fluttering. This explains it. It was going to flutter anyway.

The wastegate is from the stock turbo on the car so it should be stock non EVO pressure. I think thats 9psi?

I don't even know. But in this last video you were getting 9psi in the pipe at around 4000 rpm with only 27% throttle. So I thought maybe at full throttle you'd get more than 9psi.

The last time I took the car out with the Lock at 0% below set to 30 was the best the cars felt drivability wise since I got it.

Good.

It was pretty slow though

Yeah, Hopefully you'll be able to use as much duty cycle as you want from 4500 rpm and up. It'll be interesting to see how it goes.

 

[silentsnow31802]

Okay I messed with a few things and took some more logs/videos.
It does look like I can control the flutter by lowering the duty cycle in the areas that I was getting flutter. I just need to figure out what to set it to.
Sucks that I basically need to kneecap the turbo into building boost later than it could.
I see what you mean about wanting to control boost by throttle position.

I set the Lock at 0 and below and then 100% below settings to 0. This seems to have given full boost control to the Base Duty Cycle field which is great. The Lock At Settings 0 log is of that. I got a little flutter at the end of 3rd gear before I shift.
Lock At Settings 0:

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I set the Base Duty Cycle from 2000 to 4000 to zero so it should be on wastegate pressure until 4000ish RPM. The logs show 9psi max until 4000rpm when it spikes because the settings sharply change. I did put my foot down at then end because I wanted to see AFR when it transitioned.
2000-4000 Set To Zero:

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I was able to do a quick 2nd gear pull. Once again I wanted to see the transition in the Base Duty Cycle setting when it changes from 0 to 75 at the 4000 to 4500rpm transition.
2nd Gear Quickie:

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[We're on Boost]

Oops I see 2 of the log names are swapped around. The log named 2000 - 4000 is actually the 2nd gear quickie. The log named 2nd gear quickie is actually the 2000-4000 set to zero.
The actual 2nd gear quickie log does verify that your wastegate "spring pressure" is about 9 or 10 psi.
And it also verifies that yes, it's throwing away performance that you could otherwise have below 4500 rpm.

Both logs show how the wg duty cycle climbs (ramps) up from 0 at 4000rpm to the table value at 4500 rpm with kind of a linear interpolation ramp-up, and that seems like "as designed" or as expected.

In the "2000 4000 set to zero" video, when you are in 3rd gear, right at 21 seconds I hear something like wind noise for an instant, then you step on the gas to 100%. Was it starting to flutter right there at 21 seconds in the video just before you put your foot down? In the log at that point I don't see any breakup in the BoostPSI curve. It looks ok there, flutter wise, and there was some duty cycle there.

It helps that we can see the speedometer and tach a little bit in the videos - helps with syncing the video to the log.

 

[silentsnow31802]

Oops I see 2 of the log names are swapped around. The log named 2000 - 4000 is actually the 2nd gear quickie. The log named 2nd gear quickie is actually the 2000-4000 set to zero.
The actual 2nd gear quickie log does verify that your wastegate "spring pressure" is about 9 or 10 psi.
And it also verifies that yes, it's throwing away performance that you could otherwise have below 4500 rpm.

Both logs show how the wg duty cycle climbs (ramps) up from 0 at 4000rpm to the table value at 4500 rpm with kind of a linear interpolation ramp-up, and that seems like "as designed" or as expected.

In the "2000 4000 set to zero" video, when you are in 3rd gear, right at 21 seconds I hear something like wind noise for an instant, then you step on the gas to 100%. Was it starting to flutter right there at 21 seconds in the video just before you put your foot down? In the log at that point I don't see any breakup in the BoostPSI curve. It looks ok there, flutter wise.

It helps that we can see the speedometer and tach a little bit in the videos - helps with syncing the video to the log.

Oops indeed. I swapped two of them because I made that mistake. I apparently fixed the wrong ones and broke it even more .

Yes it did start to flutter at that point. It happened so late and so quick that it didnt register in my head that it happened until after I put my foot down. I thought I was in the clear. It had to have been right on the edge. Im not on a PC that can view those logs at the moment but if I remember right the AFR got a little weird right that the point before I put my foot down when the flutter started.

Yea I was doing the same. Matching the RPM with the log. I try to start them at about the same time but I only have so many hands to do things.