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Underboost Code at redline

PowerDemon

Autocross Champion
Location
Fredericksburg, VA
Car(s)
Mk7 GTI
Stock location APR, FMIC Baun Performance, budget Magic/Majesty. If you can’t afford to get an IC at the moment keep your foot out of it if your IATs are 120 or higher until you can upgrade your IC. IMO
 

kmarriner

Go Kart Newbie
Location
Tempe, AZ
Car(s)
2019 GTI SE DSG
Stock location APR, FMIC Baun Performance, budget Magic/Majesty. If you can’t afford to get an IC at the moment keep your foot out of it if your IATs are 120 or higher until you can upgrade your IC. IMO
I am going with Majesty for now, I really like Jake's product but cant afford that now; May goto it later. I was mainly curious why Diggs was going against the grain and suggesting FMIC vs Stock location.
 

Chogokin

Autocross Champion
Location
So Cal
Car(s)
GTI Sport | Audi A3
Its sitting in between the AC condenser and radiator. I need an intercooler too. I going with a front mount. Mainly for ease of installation.😁
 

speed_junkie

New member
Location
Tampa
Car(s)
MK7.5 GTI & GSXR1000
Earlier this week on Facebook someone posted that they got an underboost code and epc light at redline in a high gear and that it was repeatable for them, basically they were just running through the gears at full throttle and on the 4-5 shift they get the code.


I realized that I had never tried doing that in my new gti, so that night I did the same trial as they did and logged it, getting on it from 3rd at 40 like a normal logging run but continuing all the way through 4th and into 5th. Right at redline in 4th as I was shifting into 5th I got the same code and went into limp mode.

We both drive 2019 GTIs and are tuned using accessports by the same tuner, so I thought maybe it was tune related. So the next night I tried a completely different tune from another tuner and got the code at the top of 3rd this time.


Now I am not good at reading logs and understanding them. Tuner says it could be a boost leak, or a problem with the wastegate or DV.
I definitely have done this before on my previous 2017, and never threw a single code.

Has anyone with a 2019 run into issues with the DV, wastegate, or had a boost leak from the factory? The only mod to my car other than the tune is an intake, but that's pre turbo and shouldn't cause a leak or anything. I still have to look and see if I can find a leak, but I've never done it before so it might be fruitless.

Any other things I should look for?
I experienced the same thing the other day when redlining third gear; went into limp mode and threw a code and EPC light. Mine is a manual transmission, so I clutched it, cut power, then restarted the engine and everything came back to normal. I think it's a self-preservation feature my Cobb tune intentionally added or preserved from the original configuration. Top speed so far is 150 MPH, by the way. We'll see what it'll do when I have more room to run.
 

PowerDemon

Autocross Champion
Location
Fredericksburg, VA
Car(s)
Mk7 GTI
I experienced the same thing the other day when redlining third gear; went into limp mode and threw a code and EPC light. Mine is a manual transmission, so I clutched it, cut power, then restarted the engine and everything came back to normal. I think it's a self-preservation feature my Cobb tune intentionally added or preserved from the original configuration. Top speed so far is 150 MPH, by the way. We'll see what it'll do when I have more room to run.

Do you remember the ambient temp, or if your IAT’s were high? Do you have an upgraded intercooler?
 

jimlloyd40

Autocross Champion
Location
Phoenix
Car(s)
2018 SE DSG
Stock location APR, FMIC Baun Performance, budget Magic/Majesty. If you can’t afford to get an IC at the moment keep your foot out of it if your IATs are 120 or higher until you can upgrade your IC. IMO

In Phoenix in the summer IAT's are close to 120 the instant you start your car.
 

2slowvw

Moderator
Location
VA
Car(s)
2016 GTI
You aren't doing a good job hiding them. Whose tune is that on the 12May? Yikes.

You need an intercooler or meth, badly. It's probably trying to keep you from blowing it up.

This made me look, and it was as simple as i thought lol. I suspect that 91 octane gas isnt doing you any favors either. Ambient air temp isnt even that high in the logs so ya... you gonna have more issues here as it gets warmer.
 

kmarriner

Go Kart Newbie
Location
Tempe, AZ
Car(s)
2019 GTI SE DSG
This made me look, and it was as simple as i thought lol. I suspect that 91 octane gas isnt doing you any favors either. Ambient air temp isnt even that high in the logs so ya... you gonna have more issues here as it gets warmer.

The ic was super heat soaked from stopping. If I had given it more time moving before the pull I could have gotten down to like 10 over ambient.

But the gas is bad here, I want to go eblend. I have an e50 station 1/4 mile from work/home.
 
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