Turbo issues B7 A4

[LucaTesar]

Ok so recently my 07 audi a4 popped a check engine light code P0299 for turbo underboost, at first I thought it was a minor part and ordered it but the code continued popping up and now it began affecting performance, it had low power and barelybuilds boost anymore. I also heard that your exhaust smoking is a sign, and mine is smoking although not as bad as I've seen others with bad turbos. I think my turbo needs replaced? But I dont wanna tear it open and dive into it while it could be something else, as that P0299 code could be for any number of things. Does anyone know for sure if I need to replace my turbo? A way I can find out if it's good or not? And if it is whether i just replace the whole turbo or can repair it?
First car plz be patient with me haha any help is greatly appreciated

[HerNameIsBeast]

Ok so recently my 07 audi a4 popped a check engine light code P0299 for turbo underboost, at first I thought it was a minor part and ordered it but the code continued popping up and now it began affecting performance, it had low power and barelybuilds boost anymore. I also heard that your exhaust smoking is a sign, and mine is smoking although not as bad as I've seen others with bad turbos. I think my turbo needs replaced? But I dont wanna tear it open and dive into it while it could be something else, as that P0299 code could be for any number of things. Does anyone know for sure if I need to replace my turbo? A way I can find out if it's good or not? And if it is whether i just replace the whole turbo or can repair it?
First car plz be patient with me haha any help is greatly appreciated

Did you replace N75 valve (turbo boost solenoid)? Or Diverter Valve if you have an older version that breaks easily? For me, P0299 code was caused by bad N75 valve. At first I replace Diverter Valve and that didnt help. Then, I adjusted my turbo (most people won't recommend doing that but there is a DIY in case you are interested) but the code persisted. Finally, I got to N75 valve and it solved the under boost. All of the above are cheap to try before tearing it all apart. Good luck.

Sent from my Pixel 4 using Audizine mobile app

[LucaTesar]

Haha yes in fact the part I ordered is my N75 valve which what I thought it was and as soon as it gets here I'll replace it. But could the N75 valve be causing the slight lack of power and boost? It still gets up to speed it just takes a while longer and feels buggy could the N75 he responsible?

[HerNameIsBeast]

Haha yes in fact the part I ordered is my N75 valve which what I thought it was and as soon as it gets here I'll replace it. But could the N75 valve be causing the slight lack of power and boost? It still gets up to speed it just takes a while longer and feels buggy could the N75 he responsible?

Yes. Mine was very slow to boost with bad N75. It would still speed up but just much slower even in sport mode. It is somewhat of a bitch to replace though. I'd recommend removing the bumper and putting the front into service position. I had issues removing crash bar so I had to do it without service position. It took a while and my hands were all scratched to shit.

Sent from my Pixel 4 using Audizine mobile app

[LucaTesar]

Yeah I heard it was a pain to get to as well, but somebody said I could access it from underneath the same way I accessed the diverter valve so hopefully that works. Thanks for the help it's very appreciated !
Also, what were you referring to with the DIY readjusting your turbo?

Sent from my SM-G935V using Audizine Forum mobile app

[HerNameIsBeast]

Yeah I heard it was a pain to get to as well, but somebody said I could access it from underneath the same way I accessed the diverter valve so hopefully that works. Thanks for the help it's very appreciated !
Also, what were you referring to with the DIY readjusting your turbo?

Sent from my SM-G935V using Audizine Forum mobile app

https://www.audizine.com/forum/showthread.php?t=420536

Proceed at your own risk. Bunch of people on here will yell at you if you try to do it. I adjusted mine about 2-3 turns and things seem fine. Also, you don't need to build that tool to pressurize it, you can just turn it with long reach pliers. It is just a bit harder to turn. Overall, I would try replacing N75 first and if that doesn't help, as a last resort, I would go for wastegate adjustment. Like I said, proceed at your own risk.

Sent from my Pixel 4 using Audizine mobile app

[HerNameIsBeast]

Yeah I heard it was a pain to get to as well, but somebody said I could access it from underneath the same way I accessed the diverter valve so hopefully that works. Thanks for the help it's very appreciated !
Also, what were you referring to with the DIY readjusting your turbo?

Sent from my SM-G935V using Audizine Forum mobile app

I don't remember being able to reach it from underneath but maybe I am wrong. It's been 6 months now

Sent from my Pixel 4 using Audizine mobile app

[LucaTesar]

Ok thanks once N75 arrives will install that and see how she runs . Thx for help
Will prolly be back if it doesnt work

Sent from my SM-G935V using Audizine Forum mobile app

[HerNameIsBeast]

Ok thanks once N75 arrives will install that and see how she runs . Thx for help
Will prolly be back if it doesnt work

Sent from my SM-G935V using Audizine Forum mobile app

Np. Good luck.

Sent from my Pixel 4 using Audizine mobile app

[Jeevan]

lets cut the chase, If you replaced DV already and you still wont boost, You need a new turbo. Adjusting waste gate wont work when the turbo is not boosting at all. In other words, its in stage 4 cancer


Sent from my iPhone using Audizine

[LucaTesar]

It still builds boost just takes a longer amount of time to build up to full boost

Sent from my SM-G935V using Audizine Forum mobile app

[HerNameIsBeast]

lets cut the chase, If you replaced DV already and you still wont boost, You need a new turbo. Adjusting waste gate wont work when the turbo is not boosting at all. In other words, its in stage 4 cancer


Sent from my iPhone using Audizine

It sounded to me like he was having a slight lack of power and not a total boost loss which is why I thought it could be the N75 first.

Sent from my Pixel 4 using Audizine mobile app

[vvenom800tt]

N75 and DV first.

Then if still no boost then just adjust the wastegate.

If then no boost replace the turbo.


Sent from my SM-G981U1 using Audizine Forum mobile app

[LucaTesar]

Yup planning on n75 first, already checked DV there's no tear in gasket it's all good, so if n75 doesnt do it I'll try taking the turbo off looking at wastegate try to adjust it. It is a first car for me so finance is a big part so I hope it will be one of these smaller easier fixes

Sent from my SM-G935V using Audizine Forum mobile app

[HerNameIsBeast]

Yup planning on n75 first, already checked DV there's no tear in gasket it's all good, so if n75 doesnt do it I'll try taking the turbo off looking at wastegate try to adjust it. It is a first car for me so finance is a big part so I hope it will be one of these smaller easier fixes

Sent from my SM-G935V using Audizine Forum mobile app

You dont need to take it off to adjust it. Can be done from underneath. There isn't much room but very possible.

Sent from my Pixel 4 using Audizine mobile app

[LucaTesar]

Ok awesome that makes it alot simpler, I assume it explains it all in the link you sent me? Haven't looked at it yet but I will use it if and when I do it


Sent from my SM-G935V using Audizine Forum mobile app

[HerNameIsBeast]

Ok awesome that makes it alot simpler, I assume it explains it all in the link you sent me? Haven't looked at it yet but I will use it if and when I do it


Sent from my SM-G935V using Audizine Forum mobile app

Yeah, it is all there. Also, read comments. There is a lot of good info as well.

Sent from my Pixel 4 using Audizine mobile app

[vvenom800tt]

Yup planning on n75 first, already checked DV there's no tear in gasket it's all good, so if n75 doesnt do it I'll try taking the turbo off looking at wastegate try to adjust it. It is a first car for me so finance is a big part so I hope it will be one of these smaller easier fixes

Sent from my SM-G935V using Audizine Forum mobile app

You can adjust the wastegate on the car from the top.

You need two long needle nose pliers to turn the rod and hold, turn rod and hold. Turning the rod clockwise if youre standing in front of the car. So you're moving your hands up when turning.

Its super tight. You get like 30° max i think but it works.

Just take off the intake tube and box.

If you have the nut on the rod you might able to get a wrench on it. I dont so yours may vary. I just did mine a month ago. Went from very sporadic and terrible boost to more than ive ever felt. 24psi now on my tune.

Sent from my SM-G981U1 using Audizine Forum mobile app

[LucaTesar]

Ok cool thanks and just turn clockwise until its tight?

Sent from my SM-G935V using Audizine Forum mobile app

[HerNameIsBeast]

You can adjust the wastegate on the car from the top.

You need two long needle nose pliers to turn the rod and hold, turn rod and hold. Turning the rod clockwise if youre standing in front of the car. So you're moving your hands up when turning.

Its super tight. You get like 30° max i think but it works.

Just take off the intake tube and box.

If you have the nut on the rod you might able to get a wrench on it. I dont so yours may vary.

Sent from my SM-G981U1 using Audizine Forum mobile app

Sounds like not much more room than from the bottom. It was a pain as well but I didnt have to remove anything since I didn't have the belly pan back then.

Sent from my Pixel 4 using Audizine mobile app

[LucaTesar]

Ok after done with n75 if that doesnt fix it I'll try that, good to know I could try from top or bottom so I have options. Thanks again all for the assistance its lifesaving


Sent from my SM-G935V using Audizine Forum mobile app

[Jeevan]

I would start with cheapest option first- Boost leak test which is free. Then DV check, N75 check. After that remove oxygen sensor, inspect the waste gate door. if the play is minimal, adjusting wastegate will work or else, it needs a new turbo

this is how you inspect the wastegate door

remove the oxygen sensor pre-cat, insert a boroscope and see if the door is loose and rattling when you start the car for 2 secs( if you kept car running for more that 2 secs, you might feel the exhaust gasses. this requires 2 people. 1 to start and stop car quickly and other to monitor boroscope). Watch this explanation from humble mechanic

https://youtu.be/7fk6cSDE3hE

https://youtu.be/Cl4AuMc8zfg

If the play is very minimal, you can get away with adjusting the length of wastegate arm to tighten/minimize the wastegate door rattle.

https://www.audizine.com/forum/showt...ate-Adjustment


Sent from my iPhone using Audizine

[LucaTesar]

Thanks man! Tons of help. Where can I get a boost leak test done?

Sent from my SM-G935V using Audizine Forum mobile app

[StylinS-line]

Can you hear a whistling on acceleration? I replaced a hose under the intake and it popped off and I was getting an underbooost code , look for any oil spray even if it’s minimal

I normally am 17psi peak , and was only hitting 13 , power loss was very noticeable, and so was the damn whistling LOL

[LucaTesar]

No I didnt hear any whistling, plus my engine only runs at around 8 to 10 psi stock i beleive

Sent from my SM-G935V using Audizine Forum mobile app

[Jayz691]

Stock b7 should peak at 12-13psi.

Sent from my LM-G710VM using Audizine Forum mobile app

[LucaTesar]

N75 valve came in today! Replaced it, and now the car feels like it is building boost again and feels about as powerful as before, however it still popped the check engine light same P0299 code as before, even though it is acting fine again? Will test drive more tommorow see how it behaves
Any ideas?

Sent from my SM-G935V using Audizine Forum mobile app

[LucaTesar]

N75 valve came in today! Replaced it, and now the car feels like it is building boost again and feels about as powerful as before, however it still popped the check engine light same P0299 code as before, even though it is acting fine again? Will test drive more tommorow see how it behaves
Any ideas?Screenshot_20210117-195602_RepairSol2.jpg

Sent from my SM-G935V using Audizine Forum mobile app

[Jeevan]

N75 valve came in today! Replaced it, and now the car feels like it is building boost again and feels about as powerful as before, however it still popped the check engine light same P0299 code as before, even though it is acting fine again? Will test drive more tommorow see how it behaves
Any ideas?Screenshot_20210117-195602_RepairSol2.jpg

Sent from my SM-G935V using Audizine Forum mobile app

read my comments again and digest them

[LucaTesar]

Yes thank you alot its very helpful stuff, I was able to get a hand on my wastegate actuator arm, and thankfully there is little to no play at all. Seeing as the car is performing better, I'm going to take another look at my DV as well as continue to see how the car behaves

Sent from my SM-G935V using Audizine Forum mobile app

[LucaTesar]

Also thinking about getting a go fast bits DV+ blow off valve, any opinions on those? Do they hinder the engine in any way?

Sent from my SM-G935V using Audizine Forum mobile app

[vvenom800tt]

Also thinking about getting a go fast bits DV+ blow off valve, any opinions on those? Do they hinder the engine in any way?

Sent from my SM-G935V using Audizine Forum mobile app

DO NOT get the dv+. Its of no help at all. Several people have had issues using it, including myself. Dont waste the money.

Stick with a rev D oem valve.

I'd double check the crack pressure on the wastegate. Mine was low before and built boost slowly, as well as p0299 code. No more issues after tightening it up.



Sent from my SM-G981U1 using Audizine Forum mobile app

[LucaTesar]

Ok thanks for a heads up on the dv+ . You just suggest replacing the diverter valve with an identical new oem one?
What are you referring to with crack pressure on my wastegate?
Drove more today, car still seems buggy


Sent from my SM-G935V using Audizine Forum mobile app

[Jay-Bee]

DO NOT get the dv+. Its of no help at all. Several people have had issues using it, including myself. Dont waste the money.

Stick with a rev D oem valve.

I'd double check the crack pressure on the wastegate. Mine was low before and built boost slowly, as well as p0299 code. No more issues after tightening it up.



Sent from my SM-G981U1 using Audizine Forum mobile app

Plenty of people running the GFB DV+ myself included with zero issues. Performs better than stock.

Rev G is a better DV if youre gonna go OE anyway.

[LucaTesar]

Ok so GFB DV+ could help?
Also what are you all referring to with the rev D or rev G diverter valves? Never heard the terminology before

Sent from my SM-G935V using Audizine Forum mobile app

[Jay-Bee]

Ok so GFB DV+ could help?
Also what are you all referring to with the rev D or rev G diverter valves? Never heard the terminology before

Sent from my SM-G935V using Audizine Forum mobile app

Rev G is the older rubber style, fails more often but (most say) it holds up better to boost, Rev D is the plastic piston and is more reliable long term but doesn't seal as well.

DV+ is the best of both, tighter spring/seal and a metal piston.

[Jay-Bee]

"D" on left ... "G" on right

[LucaTesar]

Ok so would you reccomend I buy a new rev G or D to go along with the DV+?

Sent from my SM-G935V using Audizine Forum mobile app

[Jayz691]

If using dv+, dontvreally matter which ya use. If staying stock, I prefer the rev G..

Sent from my LM-G710VM using Audizine Forum mobile app

[vvenom800tt]

Plenty of people running the GFB DV+ myself included with zero issues. Performs better than stock.

Rev G is a better DV if youre gonna go OE anyway.

I had nothing but issues with mine. Car just didnt run well with it.

Sent from my SM-G981U1 using Audizine Forum mobile app