Over Boost Code

[Sammiboy98]

Plugged in the snap-on scanner at work and found that my car is over boosting. (P1555) I know that I’m the past I had a bad wastegate line so I replaced it with a soft line and pressure seems to hold. Any ideas of certain places you recommend checking first?


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[Corradovolksb]

Leaking WG line is usually the main issue when it comes to overboost. Rare case would be a bad n75. Is your car stock?


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[fR3ZNO]

Another possibility is a leaking diaphragm on the wastegate actuator itself.

[Sammiboy98]

It’s a stock car with the APR stage 2 tune. I recently pulled the engine and swapped both turbos from ECS. So genuine turbos, the real deal, and they’re brand new so I’m really crossing my fingers the wastegates aren’t bad.


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[cu52]

Check your wastegates again. Pull the grey line off the N75 and blow air ~8 PSIto see if you can hear them open and close or the other method if you have a vacuum pump/ mitivac see if they hold vacuum. I had the same issue on my passenger side. Blew the silicone part at the connection to the turbo, replaced it with braided stainless -4an line line melted, too hot to manifold as I repalced it without pulling the engine. Held pressure for 1-2 days then blew again. Replaced it again with -4an line covered in heat protectant wrap and that has held, but damage might have already been done to the turbo...

[chaos2984]

I am kinda having the same issue. So if you pull vacuum on the actuators and it holds then they are ok?

[Sammiboy98]

I’m also wondering that. Also what kind of damage can be done to the turbos. Thankfully, it’s fairly recent but fingers crossed I didn’t break anything.


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[Corradovolksb]

Try unplugging the n75 and do some 2nd and 3rd gear pulls. Stock k03 WG’s are set to 5psi so you should only boost 5psi. If you don’t you have a WG issue for sure.


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[Sammiboy98]

So the car is supposed to run 5psi of Boost stock? I have been told that it’s supposed to run 15-17psi with peaks of 20 with the stage 2 tune.


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[Corradovolksb]

So the car is supposed to run 5psi of Boost stock? I have been told that it’s supposed to run 15-17psi with peaks of 20 with the stage 2 tune.


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Stock boost is around 10psi. Stage 1 is usually 16psi taper to 13psi and stage 2 is usually 20psi taper to 13psi by redline. When your in limp mode boost is 5psi.


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[Sammiboy98]

Now my car is spitting fuel on the driver side somewhere around the fuel rail and it’s -20 F here so she’s going to have to be parked for a little while.


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[kingofqueenz788]

So I’m running a base tune pretty much, my tuner told me to disconnect the electrical connector to the n75 and do a log, my boost hits 12-13 psi, but when I’m 3rd gear around 5-6000 rpm the boost increases To 16. Also if I hold the boost at around 4-5psi and hit the glass off and on I get a weird noise like the waist gates moving back n fourth very fast I pressure tested the car and no leaks I set my waistgate cracking pressure to 9psi but worried about overworking my new turbos ny imput

[Corradovolksb]

So I’m running a base tune pretty much, my tuner told me to disconnect the electrical connector to the n75 and do a log, my boost hits 12-13 psi, but when I’m 3rd gear around 5-6000 rpm the boost increases To 16. Also if I hold the boost at around 4-5psi and hit the glass off and on I get a weird noise like the waist gates moving back n fourth very fast I pressure tested the car and no leaks I set my waistgate cracking pressure to 9psi but worried about overworking my new turbos ny imput

Sounds like you have a leak at one of your wastegate lines. That will affect your boost. If your WG’s are set to 9 psi and your hitting 12-13 and it increases to 16psi then the only thing that will cause it is a WG line leak.


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[chaos2984]

I also disconnected my n75 and I only get 5 psi. But i also hit limp mode also and it won't go over 5psi until it comes out of limp mode. I will spike about 20psi and fall to 16psi. But sometimes it will cut boost and go into limp mode. Once this weather breaks i can do some more testing. Not fun to work in sub 10F. How do you test the waste gates with a vacuum hand pump pull vacuum on the one side and see if it holds and then on the other side pull vacuum and see what psi they crack at?

[vavJETTAw36]

I also disconnected my n75 and I only get 5 psi. But i also hit limp mode also and it won't go over 5psi until it comes out of limp mode. I will spike about 20psi and fall to 16psi. But sometimes it will cut boost and go into limp mode. Once this weather breaks i can do some more testing. Not fun to work in sub 10F. How do you test the waste gates with a vacuum hand pump pull vacuum on the one side and see if it holds and then on the other side pull vacuum and see what psi they crack at?

You need to pump pressure into the WG side of the lines. I believe it's the right side (opposite of connector) on the n75. Do a quick blow with your mouth to verify.

Just pump pressure into it and if it holds then it's all good. While you are doing that, note the pressure that moves the actuator arms.


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[chaos2984]

You need to pump pressure into the WG side of the lines. I believe it's the right side (opposite of connector) on the n75. Do a quick blow with your mouth to verify.

Just pump pressure into it and if it holds then it's all good. While you are doing that, note the pressure that moves the actuator arms.


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gotcha thanks they should crack at 10 psi right.

[vavJETTAw36]

gotcha thanks they should crack at 10 psi right.

K03/K04 should crack at 6-7


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