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Old 10-12-2016, 08:06 PM   #1
thatspsychotic
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Unhappy Boost fluctuations and hesitation: APR Stage 1

I've been experiencing this gradually getting worse since flashing APR Stage 1 V2.1:



Boost fluctuations around the boost threshold along with hesitation at the same time. Consistently does this (or sounds more like compressor surge when its warmer out) in this situation.

Anyone else seen this? Maybe N75 valve problem? Tune too aggressive with using DV to control boost?
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Old 10-12-2016, 08:09 PM   #2
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I don't really think one can hear compressor surge, I think that's the most commonly confused issue with WG flutter, etc.
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Old 10-12-2016, 08:32 PM   #3
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Quote:
Originally Posted by FriggenT View Post
I don't really think one can hear compressor surge, I think that's the most commonly confused issue with WG flutter, etc.
One can definitely hear compressor surge, and I'm not sure that one can actually hear "WG flutter"




However, my video and issue I'm not suggesting that it is compressor surge, but some kind of boost control issue, like bad N75 valve, etc.
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Old 10-12-2016, 09:41 PM   #4
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Hmmm, have you done a boost leak test? Like it's trying to build and it hits that point where it starts to leak, but maybe it just seals itself. Checked the TOP connection? It bounces so fast that it looks more like a possible software issue imo.
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Old 10-12-2016, 09:44 PM   #5
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Ohhh wait, you said DV, I just saw the DV+ that doesn't always do well with some software. I'd take it off and try that first.
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Old 10-12-2016, 10:46 PM   #6
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Originally Posted by FriggenT View Post
Ohhh wait, you said DV, I just saw the DV+ that doesn't always do well with some software. I'd take it off and try that first.
Yeah that was one of my fears, the extra mass of the DV+ causing it to vent too much boost. Still seems like a backwards way of controlling boost rather than N75. Will have to pick up a rev D DV to test.
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Old 10-12-2016, 11:53 PM   #7
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Originally Posted by thatspsychotic View Post
Yeah that was one of my fears, the extra mass of the DV+ causing it to vent too much boost. Still seems like a backwards way of controlling boost rather than N75. Will have to pick up a rev D DV to test.
Just put your old one back together?
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Old 10-14-2016, 03:42 AM   #8
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Quote:
Originally Posted by thatspsychotic View Post
Will have to pick up a rev D DV to test.
I have one laying around...used it for a quick test & then took it off.
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Old 10-14-2016, 07:47 AM   #9
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Quote:
Originally Posted by snobrdrdan View Post
I have one laying around...used it for a quick test & then took it off.
If he doesn't take it then I will. I think I'm having a similar problem.
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Old 10-15-2016, 10:03 PM   #10
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Quote:
Originally Posted by snobrdrdan View Post
I have one laying around...used it for a quick test & then took it off.
What were you testing? Whether your rev G was leaking boost?

Quote:
Originally Posted by FriggenT View Post
Just put your old one back together?
I have rev G, I'm fairly sure it was leaking boost even with the V1.2 tune ages ago, thats why I went DV+ in the first place.

I would like to test rev D, but I'm not convinced that its the DV at all. The boost fluctuation is almost sinusoidal and is only a few PSI in magnitude, as if the car is hunting for the correct boost level. That is what made me think of the N75 valve first. If it is the N75, that could also make the ECU lean on the DV more to control overshoot, barely cracking the DV to modulate the pressure. Even that doesn't make a whole lot of sense, because the boost is fluctuating before it even gets to the peak boost level once things settle at >3500 RPM

I have autocross tomorrow so I can't test anything out, but I also want to rule out the low hanging fruit like cleaning the MAF, even changing out my air filter, etc. to make sure it's not something caused by wonky MAF readings. This isn't a problem in autocross because most of the time is spent over 3500 RPM in 2nd gear anyways, and the car has too much power to put to the ground well with my worn tires and stock suspension.
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Old 10-17-2016, 01:59 AM   #11
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Quote:
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What were you testing? Whether your rev G was leaking boost?
Yeah. It ended up being the tune though after I logged it and found out it wasn't leaking boost at all. It just wasn't meeting the requested PSI it was supposed to and needed some tweaking in the software
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Old 10-19-2016, 03:59 PM   #12
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While I don't have a boost gauge to see if the boost was fluctuating similar to yours, I believe I had the same issue. WOT on 3rd or 4th (I don't WOT on 5th or higher usually), and there would be a point from 2500 - 3500 RPM where it felt like an intermittent loss of power. RPMs would rise steadily, but it felt like boost was coming on and off, and you could hear a "wum wum wum" sound.

Here's a video of how it used to be:


I know it's terrible quality, but you can kind of hear at the start.

I spoke with APR and they had me try the updated 2.3b file for Stage 1. Very glad to say that the issue was fixed for me. (2.3b also fixed the odd cold start rpm issue for me that popped with with the 2.0 release.)

For reference, I'm also on a GFB DV+ (w/o the main spring).
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Old 10-19-2016, 04:06 PM   #13
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im having the same problem WOT on 3rd or 4th from 2500 - 3500 RPM
im on stg2 2.3b and it wasnt happening at first only after a couple weeks.

im also going to test boost leak and n75 but also what about pcv?
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Old 10-21-2016, 12:39 AM   #14
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I've been experiencing the same issue since updating to v2.0 several months ago. http://www.golfmk6.com/forums/showthread.php?t=106303

Seems to be the worst when it's hot/humid. After pulling logs, it looks like my throttle plate angle is closing repeatedly (throttle cut). Pull some logs and let us know what you find. I bumped down to the 91 tune, which seems to have helped.
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