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GTI MK7 BOV

git_fan

Go Kart Newbie
Location
Virginia
Car(s)
2016 GTI
so lets say you're running a bov that vents 100% to atmosphere. You shift from 2nd to 3rd, part throttle, no wide open stuff.

the ecu has metered the air that is expected to recirculate. it has accounted for that surge to return. instead your car blew it off into the atmosphere. guess what happens to your air fuel mix immediately after an upshift. and it does that, each and every time the car upshifts. over and over. every day.

lol, what would these logs even prove? both logs are of regular driving making little boost, never going past 3500 rpms, and the accelerator pedal is 95% of the time under 50%.
:unsure:

can you relog but this time send it till redline at least in third gear, if possible?
I'll keep that in mind for when I feel like changing out the parts again. I assume there should be a shift logged at redline and not getting on the brakes?
 

Keehs360

Autocross Champion
Location
Denver
Car(s)
Mk7.5
:unsure:


I'll keep that in mind for when I feel like changing out the parts again. I assume there should be a shift logged at redline and not getting on the brakes?
If I can be honest with you? Launch it and don’t stop till the top of 4th shifts to 5th. Then you can let off.

I’d honestly rather you didn’t, cuz safety and all that. If you plan on hitting the 1/4 mile track, maybe just log that day instead?
 

git_fan

Go Kart Newbie
Location
Virginia
Car(s)
2016 GTI
If I can be honest with you? Launch it and don’t stop till the top of 4th shifts to 5th. Then you can let off.

I’d honestly rather you didn’t, cuz safety and all that. If you plan on hitting the 1/4 mile track, maybe just log that day instead?
Yeah, redline on the street in 4th isn't something I would try and do. I haven't been to a drag strip, if I did go I don't think I'd want to be swapping the DV for BOV on a hot engine there.

I figured I'd give it a try to get some data on this issue, but it seems like it's going to require some unique circumstances to show the problem.
 

Keehs360

Autocross Champion
Location
Denver
Car(s)
Mk7.5
Yeah, redline on the street in 4th isn't something I would try and do. I haven't been to a drag strip, if I did go I don't think I'd want to be swapping the DV for BOV on a hot engine there.

I figured I'd give it a try to get some data on this issue, but it seems like it's going to require some unique circumstances to show the problem.
If safety is thrown out of the window, unique circumstances won’t really be needed.

but. Safety has to be a thing. I think
 

git_fan

Go Kart Newbie
Location
Virginia
Car(s)
2016 GTI
lol, what would these logs even prove? both logs are of regular driving making little boost, never going past 3500 rpms, and the accelerator pedal is 95% of the time under 50%.

so lets say you're running a bov that vents 100% to atmosphere. You shift from 2nd to 3rd, part throttle, no wide open stuff.

the ecu has metered the air that is expected to recirculate. it has accounted for that surge to return. instead your car blew it off into the atmosphere. guess what happens to your air fuel mix immediately after an upshift. and it does that, each and every time the car upshifts. over and over. every day.
I was told that logging part throttle would show the problem, @El_bigote_AJ you say that is not the case. Getting conflicting direction on what to log here.

If the problem BOVs cause only shows up with a WOT shift at redline that's a very infrequent situation for me.
 

El_bigote_AJ

Autocross Champion
Location
Las Vegas
Car(s)
2019 GTI bunny
I was told that logging part throttle would show the problem, @El_bigote_AJ you say that is not the case. Getting conflicting direction on what to log here.

If the problem BOVs cause only shows up with a WOT shift at redline that's a very infrequent situation for me.
To be transparent I didn’t know keehs360 ask you to log it based on that scenario... which I don’t think is a valid one, especially at part throttle, that’s could happen on a slow reacting MAF car but I don’t think that a speed density car with the first map sensor being so down steam from the DV would actually get affected like that.


First hand experience: I have the forge BOV and have ran it off and on a few time cause I just really liked the sound... but the reason I say “off and on” is cause it’s always had issues once the car went hybrid with higher boost levels. When the car was JB4 I would notice the delayed time to built boost back up during shifts but I dealt with it for the sound, once the car was making 28/29 psi to redline that delay was not only extremely noticeable now since in needs to build a lot more boost back up, but I started dealing with delayed times of its function for releasing the boost as well.

First time I took it off was cause I was dealing with odd moments where the DV and tune didn’t seem to play well and just felt like it wasn’t opening to let off the pressure (tune was at 26 to redline at that time)


After a while I decided to put it back on and then started dealing with this

https://www.golfmk7.com/forums/index.php?threads/low-boost-odd-condition-on-2-3rd-hard-pulls.382328/

We couldn’t break it down as you or myself would like to fully understand what was happening... but the reality of its effects were real - I removed it and it never happened again.
 
Last edited:

Keehs360

Autocross Champion
Location
Denver
Car(s)
Mk7.5
I was told that logging part throttle would show the problem, @El_bigote_AJ you say that is not the case. Getting conflicting direction on what to log here.

If the problem BOVs cause only shows up with a WOT shift at redline that's a very infrequent situation for me.
It’s easier to spot during daily normal driving. But at wot you can see how the fuel trims get dragged along a bit after upshift, even though the difference is less pronounced.

if you really really want to see it. Pull the battery so you can reset learning. Then log. You’ll be able to see it very clearly then. Especially on the first 20 miles of city driving.

why do you want to log this phenomenon anyways?
 

Keehs360

Autocross Champion
Location
Denver
Car(s)
Mk7.5
To be transparent I didn’t know keehs360 ask you to log it based on that scenario... which I don’t think is a valid one, especially at part throttle, that’s could happen on a slow reacting MAF car but I don’t think that a speed density car with the first map sensor being so down steam from the DV would actually get affected like that.


First hand experience: I have the forge BOV and have ran it of and on a few time cause I just really liked the sound... but the reason I say off and one is it’s always had issues once the car went hybrid with higher boost levels. When the car was JB4 I would notice the delayed time to built boost back up during shifts but I dealt with it for the sound, once the car was making 28/29 psi to redline that delay was not only extremely noticeable now since in need to build a lot more boost back up, but I started dealing with delayed times of its function for releasing the boost as well.

First time I took it off was cause I was dealing with odd moments where the DV and tune didn’t seem to play well and just felt like it wasn’t opening to let off the pressure (tune was at 26 to redline at that time)


After a while I decided to put it back on and then started dealing with this

https://www.golfmk7.com/forums/index.php?threads/low-boost-odd-condition-on-2-3rd-hard-pulls.382328/

We could break it down as you or myself would like to fully understand what was happening... but the reality of it the effects were real - I removed it and it never happened again.

https://www.golfmk7.com/forums/index.php?threads/low-boost-odd-condition-on-2-3rd-hard-pulls.382328/
I’m not used to seeing logs from the ea888. Does it not have a parameter that shows how much fuel the ecu had to instantly adjust at any given time? If not, then yeah I get what your saying and why you want it logged your way

sorry for conflicting opinions
 

Nineeightyone

Go Kart Newbie
Location
USA
Car(s)
2019 GTI | 2004 JSW
Quick update, after actually watching my P3 as best I can with respect for safely driving:

I'm stock tune. AFRs tend to run a tad rich right after PSSSHT noises, so I believe it's accurate to say the car is trying to accommodate for that continued spool where it's venting to atmosphere instead. However, it's not overly rich -- upper 12.x-low 13.x AFRs, then right back to a pretty steady ~14.3-14.7 range. So I think there may be some accuracy to the statement that you give up some power/speed/spool time for the sound, not sure if it causes any issues on stock trims but I figure if it starts giving me headaches, I'll revert back to DV-only. But for now, for a car that I really just enjoy on the weekends, it's entertaining and I'm fine with it. I figure a little rich is better than lean, and I'm having fun.

I don't think I'd replace the whole DV assembly with a BOV though, as it is around town it's quiet and well-behaved, but easy enough to coax moderate sounds out of it when I want. Nice middle ground, and easily reversible. I've been hearing that every so often the rubber seals on the spacer need to be checked/lubricated with oil, so I'll likely do that in the interest of testing and see how it holds up.
 

Keehs360

Autocross Champion
Location
Denver
Car(s)
Mk7.5
Quick update, after actually watching my P3 as best I can with respect for safely driving:

I'm stock tune. AFRs tend to run a tad rich right after PSSSHT noises, so I believe it's accurate to say the car is trying to accommodate for that continued spool where it's venting to atmosphere instead. However, it's not overly rich -- upper 12.x-low 13.x AFRs, then right back to a pretty steady ~14.3-14.7 range. So I think there may be some accuracy to the statement that you give up some power/speed/spool time for the sound, not sure if it causes any issues on stock trims but I figure if it starts giving me headaches, I'll revert back to DV-only. But for now, for a car that I really just enjoy on the weekends, it's entertaining and I'm fine with it. I figure a little rich is better than lean, and I'm having fun.

I don't think I'd replace the whole DV assembly with a BOV though, as it is around town it's quiet and well-behaved, but easy enough to coax moderate sounds out of it when I want. Nice middle ground, and easily reversible. I've been hearing that every so often the rubber seals on the spacer need to be checked/lubricated with oil, so I'll likely do that in the interest of testing and see how it holds up.
Sounds about right and it’s the same thing that has been determined on many different platforms for the past 15 years or so.

your engine isn’t going to blow up or anything like that. It’ll just run a hair rich, there will be a loss of spool and a slight loss in acceleration. That’s it.
 

Diggs24

Autocross Champion
Location
de plains! de plains!
Car(s)
2015 GTI; 2003 Saab
ran it of and on a few time cause I just really liked the sound... but the reason I say off and one
 

Nineeightyone

Go Kart Newbie
Location
USA
Car(s)
2019 GTI | 2004 JSW
Sounds about right and it’s the same thing that has been determined on many different platforms for the past 15 years or so.

your engine isn’t going to blow up or anything like that. It’ll just run a hair rich, there will be a loss of spool and a slight loss in acceleration. That’s it.

I'm glad to have that affirmation -- I'm alright with giving up a little performance to indulge 15-year old me, I'm not using the GTI for a racecar for quite a while at least, and it makes me happy. I'd be far more upset if I spent a significant amount of money to replace the factory DV with something else, but for a cheap mod for just a bit of sound, it's not the worst. I giggle like a schoolgirl when it's audible, but it's nice to not have it popping off all the time when I'm driving around town/trying to stay low-key.
 

Keehs360

Autocross Champion
Location
Denver
Car(s)
Mk7.5
I'm glad to have that affirmation -- I'm alright with giving up a little performance to indulge 15-year old me, I'm not using the GTI for a racecar for quite a while at least, and it makes me happy. I'd be far more upset if I spent a significant amount of money to replace the factory DV with something else, but for a cheap mod for just a bit of sound, it's not the worst. I giggle like a schoolgirl when it's audible, but it's nice to not have it popping off all the time when I'm driving around town/trying to stay low-key.
And that’s fine. People will criticize. But no one here pays for your car. You do you, clearly you’re having fun 😂 and that’s all that matters
 
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