N75 wastegate actuator valve explained/symptoms.
10-13-2015, 10:07 PM
#31
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Check engine light came on...was told wastegate valve was bad but, because it was part of the turbo itself, I WOULD NEED TO REPLACE ENTIRE TURBO??! Is this true?!!
Any/all help much appreciated
Any/all help much appreciated
10-14-2015, 04:26 AM
#32
AudiWorld Senior Member
Hi all, I have a question I hope you can help with. I have an 05 B5. When the car hits approx 65 mph it goes into limp. I have cleaned the maf, egr valve and still no joy. I now feel it could be the wastegate solenoid. IT also blows a lot of black smoke out the back, I know it's diesel but more than I would like. When I say a lot it's not filling the road but noticeable in the dark against the rear cars headlights. I've lost confidence in all my mechanics around me as they can't solve it and I don't want to tKeit to a dealer who I will pay a fortune to and maybe still not get it resolved. Any ideas?
1.8T diesel (this is the 1.8T forum)? never heard it exists.
I suspect you are in the wrong place.
10-14-2015, 04:27 AM
#33
AudiWorld Senior Member
If it is the wastegate actuator: that can be changed.
04-24-2016, 10:24 AM
#34
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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!
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!
04-26-2016, 03:07 AM
#35
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04-26-2016, 04:34 AM
#36
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I plugged it in with a regular OBD reader and it gave me the code and when I looked it up it said turbocharger wastegate solenoid A. It said one of the causes is open or short to ground. The other causes were faulty wastegate and poor electrical connection. Where would I look for the connection?
05-13-2016, 05:20 AM
#37
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Hi Guys, i wonder if i could butt into this post.
My car is a diesel Audi A2, with the 1.4 3 pot engine. I believe this is a cut down PD lump.
I have a overboot problem. I assumed that you applied vacume to gain boost, but from what i have been reading abouts the place is that you apply vacume to open the waste gate, not to close it.
I have some questions for you.
Firstly, is this correct?
If that is correct, may i ask how the car, when it over boost enters a soft limp mode. Does is hold the wastegate open eliminating boost, or does it just limit the engine in other ways so it cannot achieve boost?
The problem i have is that it seems this engine has two levels of boost. I have VAGCOM and can see the graphs of the boost etc. When driving under 2300RPM the max boost is, say, 10 PSI (value unknown, i cant remember) and it can happily hold this on the money.
But,
Venture above 2300rpm, and call for power, the boost level is raised to a higher level, which the engine then cant control (20 odd PSI), and say after 4 seconds, the power is cut and im in limp mode, with no service light, but a over boost error logged in the ecu.
Where do you think i should start? the turbo is pretty much inaccessable, i'd love to maybe clean the wastgate linkages but i cannot see them, let alone reach them. Count it be a sticky wastegate?
Leaky vacume line?
insufficent vacume getting to the N75?
Your thoughts would be greatly appriciated.
UC.
My car is a diesel Audi A2, with the 1.4 3 pot engine. I believe this is a cut down PD lump.
I have a overboot problem. I assumed that you applied vacume to gain boost, but from what i have been reading abouts the place is that you apply vacume to open the waste gate, not to close it.
I have some questions for you.
Firstly, is this correct?
If that is correct, may i ask how the car, when it over boost enters a soft limp mode. Does is hold the wastegate open eliminating boost, or does it just limit the engine in other ways so it cannot achieve boost?
The problem i have is that it seems this engine has two levels of boost. I have VAGCOM and can see the graphs of the boost etc. When driving under 2300RPM the max boost is, say, 10 PSI (value unknown, i cant remember) and it can happily hold this on the money.
But,
Venture above 2300rpm, and call for power, the boost level is raised to a higher level, which the engine then cant control (20 odd PSI), and say after 4 seconds, the power is cut and im in limp mode, with no service light, but a over boost error logged in the ecu.
Where do you think i should start? the turbo is pretty much inaccessable, i'd love to maybe clean the wastgate linkages but i cannot see them, let alone reach them. Count it be a sticky wastegate?
Leaky vacume line?
insufficent vacume getting to the N75?
Your thoughts would be greatly appriciated.
UC.
07-14-2016, 12:54 PM
#38
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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!
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!
I recently bought a 2001 a4, i believe it has a unitronic tune, i put a new turbo into it do to a bad wastegate, now the car would never let me push more than 5 psi, even after i unhook the wastegate line from the n75 the car will spike to 10 psi then jerk and shake and the cel will flash idk what is wrong with this car anymore. I need help
07-14-2016, 02:48 PM
#39
AudiWorld Senior Member
I recently bought a 2001 a4, i believe it has a unitronic tune, i put a new turbo into it do to a bad wastegate, now the car would never let me push more than 5 psi, even after i unhook the wastegate line from the n75 the car will spike to 10 psi then jerk and shake and the cel will flash idk what is wrong with this car anymore. I need help
Pressure test or 'smoker' (leak detector).
08-24-2016, 09:11 PM
#40
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Throttle response or boost leak?
Okay on my 2000 1.8 Audi TT I'm having a problem. I'm hitting 10lbs of boost but when I go to push the throttle past half way the car just shutters a bunch and won't go any faster so I just ease it constantly all the time. I'm gonna check for a boost leak again tomorrow but If that doesn't work idk . But main problem is throttle response. Thanks if you answer this