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N75 wastegate actuator valve explained/symptoms.

N75 wastegate actuator valve explained/symptoms.

 
Old 08-10-2017, 07:24 AM
  #41  
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Why am I only getting 5lbs of boost my car was acting up turns out it was a coil so I changed it now I'm only getting 5lbs of boost
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Old 08-31-2017, 09:03 AM
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Just registered so I can say I had this exact problem with my n75. Fine then as it got warmer boost would disappear but would give a correct reading cold.

Replaced and it's back to where it should be

thank you.
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Old 10-24-2017, 01:18 AM
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Default Amarok tubo replaced, N75 valves replaced

Hi Ouwdee

my Amaroks tdi turbo has blown (the small one)at low revs/ idle speeds and im told there was damage to the bearings inside the core. Its a 2011 model . 164000km
i heard a weird WHISTLING when it happened...like it was spiking. Total loss of power and when we took the small turbo out, you could barely turn it by hand.
my mechanic replaced the inner core with a Turbo Exchange unit. He is a competant turbo guy but he doesnt have any machines/programs to calibrate and do proper diagnostics.
we also replaced both the N75 valves.
the fault seemed to clear - even after driving it really hard up hills. But 3days later the engine lamp and turbo lamp started flashing again - low boost error.
it seems to have vacuum as ive witnessed the actuators at turnover. Idling is smooth, but consumption has gone up. My mechanic says the tubo is spooling but has insufficient boost.
Whereto now? Programming? Actuators? EGR?
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Old 10-04-2018, 07:55 PM
  #44  
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Default Mk4 GTI 1.8t

I'm having issues with boost. I'm not sure what it could be. I changed and checked all vacuum and boost lines. N75 valve is brand new. I have spikes in boost as soon as I get into boost it seems like it's choking itself. It spikes to 20 psi and then crashes to 5 psi and had a hard time getting to 15 psi. It seems like it wants to boost but something is not letting it boost. There is a tune on the car but I'm not sure what kind. I'm starting to think maybe an intake hose is collapsing on me while going into boost. Any opinions would be helpful. Pleaseet me know if anyone else is having or solved this issue.
​​​​​​
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Old 03-03-2019, 04:20 PM
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Default can i boost tap into this line?

Originally Posted by ouwdee View Post
alright first off this is my first thread im posting on the audi forums, and ill try to keep posting about every problem i encounter with my TT as long as there isnt posts about the same problem already. the n75 valve is a common topic.. yet i have not found a thread about it which completly explains EVERYTHING. so im gonna give it a go. if anyone as anything to add please do so. cheers.

EXPLANATION
The N75 valve controls the turbo wastegate actuator via directing air pressure to it by actuating a tiny solenoid when the ECU decides its neccesary. this solenoid can turn on and off VERY fast to keep the boost at the proper constant. basically it prevents overboost electronically instead of relying on a set tension spring on your wastegate. Its a plastic "T" with a small solenoid and the 2 prong plug on it. 3 hoses: 1 from the intake hose before the turbo, 1 from the intake pipe right after the turbo, 1 from the wastegate actuator.

SPECS: the long part of the "T" which is connected to the intake tube before the turbo SHOULD NOT leak if you blow air into the other 2 nipples. If it does AT ALL you need a new one. if you take a resistance reading between the 2 prongs in the plug it should be between 25-35 ohms.
*****VERY IMPORTANT!******* this is where i was stuck. I had the proper ohm reading, yet mine was still acting up. SO! run extremely hot water on the solenoid, even put it in a boiling pot of water, because when this little sucker heats up from engine heat and moving back and forth the resistance reading goes UP! i just ran hot tap water on mine and i got 40 ohms, 5 over the tolarence. completly made sense why my car would slowly stop boosting once it warmed up. ALSO. it in NOT true that if your n75 is malfunctioning it will throw a code. it the resistance can get out of whack, but something it doenst go past the ECUs set parameters to throw the code, so electronically the ecu finds it acceptable, when in all reality its not mechanically functioning properly.

IN MY OPINION: (dont bite my head off for this one people.)
don't buy the RACE n75. get an N75J and stick with BOSCH, unless youre going to a manual boost controller of course.
mine which failed was a race. not only is it lower quality and shorter lifespan then bosch. it also spikes your boost pretty hard, boosts quite late, and gives a stiff boost curve. the N75J has a nice smooth boost curve, it doesnt just come outa nowhere and kick you in the ***. but the last parts just my opinion.

BEFORE YOU EVEN START THINKING ITS YOUR N75
basics. make sure there are no leaks in your system. do you have a rough idle? change your little braided vacuum hoses ASAP. theyre garbage. rev your engine in neutral, even take a hose off after the intake and listen for your turbo spooling. your turbo will always spool, unless its shot of course. CLEAN YOUR MAF! the ecu will not close the wastegate unless it senses a massive amount of air being sucked into the engine by the open throttle plate. if the maf is not sending the correct number you might not boost. check your wastegate actuator diaphram by applying pressurized air in small bursts to the hose that goes to it from the n75. you should hear a "pop!" sound when you let the pressure off, since pressure opens the valve, when you let the pressure out you hear the valve seat itself/ the diaphram get pushed back by the spring inside it. if you havent already, GET A BOOST GAUGE! it will serve you better with your investigation then a VAG com.

I am a certified mechanic (a young one) , so if you have any questions whatsoever just shoot me a PM and ill do my best to help you out. I dont see a whole lot of german cars at my shop, though id love to. but you learn something every day..

anyways feel free to add to this guys! the more the merrier!


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Old 03-03-2019, 04:25 PM
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Default 2013 Audi A4 B8.5

That was the only rubber hose i could find.
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Old 03-03-2019, 04:29 PM
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Default 2013 A4B8.5

2013 A4 B8.5




[/QUOTE]
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Old 03-25-2019, 10:08 AM
  #48  
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Default 2007Audi A4 2.0T - Question on N75

Originally Posted by ouwdee View Post
alright first off this is my first thread im posting on the audi forums, and ill try to keep posting about every problem i encounter with my TT as long as there isnt posts about the same problem already. the n75 valve is a common topic.. yet i have not found a thread about it which completly explains EVERYTHING. so im gonna give it a go. if anyone as anything to add please do so. cheers.

EXPLANATION
The N75 valve controls the turbo wastegate actuator via directing air pressure to it by actuating a tiny solenoid when the ECU decides its neccesary. this solenoid can turn on and off VERY fast to keep the boost at the proper constant. basically it prevents overboost electronically instead of relying on a set tension spring on your wastegate. Its a plastic "T" with a small solenoid and the 2 prong plug on it. 3 hoses: 1 from the intake hose before the turbo, 1 from the intake pipe right after the turbo, 1 from the wastegate actuator.

SPECS: the long part of the "T" which is connected to the intake tube before the turbo SHOULD NOT leak if you blow air into the other 2 nipples. If it does AT ALL you need a new one. if you take a resistance reading between the 2 prongs in the plug it should be between 25-35 ohms.
*****VERY IMPORTANT!******* this is where i was stuck. I had the proper ohm reading, yet mine was still acting up. SO! run extremely hot water on the solenoid, even put it in a boiling pot of water, because when this little sucker heats up from engine heat and moving back and forth the resistance reading goes UP! i just ran hot tap water on mine and i got 40 ohms, 5 over the tolarence. completly made sense why my car would slowly stop boosting once it warmed up. ALSO. it in NOT true that if your n75 is malfunctioning it will throw a code. it the resistance can get out of whack, but something it doenst go past the ECUs set parameters to throw the code, so electronically the ecu finds it acceptable, when in all reality its not mechanically functioning properly.

IN MY OPINION: (dont bite my head off for this one people.)
don't buy the RACE n75. get an N75J and stick with BOSCH, unless youre going to a manual boost controller of course.
mine which failed was a race. not only is it lower quality and shorter lifespan then bosch. it also spikes your boost pretty hard, boosts quite late, and gives a stiff boost curve. the N75J has a nice smooth boost curve, it doesnt just come outa nowhere and kick you in the ***. but the last parts just my opinion.

BEFORE YOU EVEN START THINKING ITS YOUR N75
basics. make sure there are no leaks in your system. do you have a rough idle? change your little braided vacuum hoses ASAP. theyre garbage. rev your engine in neutral, even take a hose off after the intake and listen for your turbo spooling. your turbo will always spool, unless its shot of course. CLEAN YOUR MAF! the ecu will not close the wastegate unless it senses a massive amount of air being sucked into the engine by the open throttle plate. if the maf is not sending the correct number you might not boost. check your wastegate actuator diaphram by applying pressurized air in small bursts to the hose that goes to it from the n75. you should hear a "pop!" sound when you let the pressure off, since pressure opens the valve, when you let the pressure out you hear the valve seat itself/ the diaphram get pushed back by the spring inside it. if you havent already, GET A BOOST GAUGE! it will serve you better with your investigation then a VAG com.

I am a certified mechanic (a young one) , so if you have any questions whatsoever just shoot me a PM and ill do my best to help you out. I dont see a whole lot of german cars at my shop, though id love to. but you learn something every day..

anyways feel free to add to this guys! the more the merrier!
Hi there! Would a bad N75 keep the wastegate open and create a buildup of oil? I get a huge, and I mean HUGE smoke screen blowoff when the car needs boost going uphill, or simply merging on highway. Thank you
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Old 07-05-2019, 11:27 AM
  #49  
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Which N75 Valve is the best option for the 1.8T engine ?
Why ?
( There seems to be so many different versions of the N75 Valve )

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