N75 wastegate actuator valve explained/symptoms.
01-03-2011, 04:18 AM
#11
Audiworld Junior Member
Thread Starter
i just found out that i am chipped by APR i guess. i had the car for 2 years. when i press and hold the set (cruise), my engine light blinks once 4x then after that it blinks 2x consecutively. so i tried the first 1 time blink and release it and turn of the ignition and turned it back on. i drove it and floored it in 2nd and 3rd gear getting only 10psi boost. i tried the second program which blinks 2x consecutively and floored it in 2nd and 3rd gear boosting only 15 psi max. from what i heard is im suppposed to boost 18-20 psi. i believed the car was chipped in CA because thats where i got it and im now in TN and im using 93 octane gas. would that make any difference since in cali we only have 91 octane? could that be the reason im not hitting 20psi?
also, apr or revo technic (which ever program you have) should have your cars vin # on file. they take it down in case your ecu ever gets flashed by the dealer/ mechanic, etc. if it happens you contact them and they will put it back on for you for free. so try contacting a shop that carries them, or just shoot the companies an email ( might take a while to reply tho...) and ask them what octane program your car has.
01-11-2011, 11:46 AM
#12
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well good news is- theres nothing wrong with your car.
being that the turbo system is completly electronically controlled- your tt will only boost to 11 psi at partial throttle. partial throttle- partial psi.
you dont hit full 15 psi boost in 1st gear because its simply too short of a gear. (dumb gear ratio, really ruins the car.)
and like you said- 2nd and 3rd- full throttle you get your boost. the turbo has enough time to spool and your throttle position sensor is letting the ecu know that youre requesting full potential.
i actually noticed with my car that the ecu picks up on my driving habbits. i have the 93+ octane program on my 225hp.
with the program it pushes 20 psi, peaks out at 22 for a split second.
i drove the car sorta like a grandma for about a month, and i tried to open her up and i couldnt get the boost past 17 psi.
so i kept opening her up for the next couple days, and its like the car realized that it had to boost harder, it started, and kept boosting to 20 consistently once again.
being that the turbo system is completly electronically controlled- your tt will only boost to 11 psi at partial throttle. partial throttle- partial psi.
you dont hit full 15 psi boost in 1st gear because its simply too short of a gear. (dumb gear ratio, really ruins the car.)
and like you said- 2nd and 3rd- full throttle you get your boost. the turbo has enough time to spool and your throttle position sensor is letting the ecu know that youre requesting full potential.
i actually noticed with my car that the ecu picks up on my driving habbits. i have the 93+ octane program on my 225hp.
with the program it pushes 20 psi, peaks out at 22 for a split second.
i drove the car sorta like a grandma for about a month, and i tried to open her up and i couldnt get the boost past 17 psi.
so i kept opening her up for the next couple days, and its like the car realized that it had to boost harder, it started, and kept boosting to 20 consistently once again.
01-17-2011, 04:46 AM
#13
Audiworld Junior Member
Thread Starter
if you wanna give this a try, just pop your negative battery cable off the battery ovenight.
11-16-2011, 07:00 PM
#14
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So I just picked up a Giac chipped 03 a4 avant 5mt 1.8t the other day and am having issues overboosting when cold. I dont have a boost gauge but is pulling very hard for about 2-3 mins until warming up then all of a sudden looses all signs of boost. It pulls like a 1.8 with no turbo when warm. I am going to swap in a new n75 tommorow and see if it does the trick....any other suggestions? It almost seems like the wastegate is stuck open during cold or running lean when cold then when warm the wastegate is closed..?
this sounds alot like the OP's problem...any suggestions?
this sounds alot like the OP's problem...any suggestions?
09-26-2012, 01:17 PM
#15
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Problem S3 BAM engine.
Hey everyone. I'm new here this is my first post. I'm having inconsistent turbo pressure on my S3. I don't have a boost gauge but I can feel it inconsistent, and suddenly dropping pressure. Sometimes it just seems like is over boosting, until I hear like an air release and pressure drops down, like there is no turbo running, just a little bit. Don't now if this can be the n75 valve? Or the DV is broken? Or idk. Car stock, only decat and KN cone filter. I live in Venezuela so parts are not easy to find around here, I just wanna be sure what to buy or to do. Thinking of doing the n249 bypass. What do you think?
09-26-2012, 01:19 PM
#16
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So I just picked up a Giac chipped 03 a4 avant 5mt 1.8t the other day and am having issues overboosting when cold. I dont have a boost gauge but is pulling very hard for about 2-3 mins until warming up then all of a sudden looses all signs of boost. It pulls like a 1.8 with no turbo when warm. I am going to swap in a new n75 tommorow and see if it does the trick....any other suggestions? It almost seems like the wastegate is stuck open during cold or running lean when cold then when warm the wastegate is closed..?
this sounds alot like the OP's problem...any suggestions?
this sounds alot like the OP's problem...any suggestions?
09-27-2012, 04:29 PM
#17
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audi a4 1.8t sports no boost at all
i got this car about 6 munths ago and my brother said turbo not booting so i got a gauge and installed it and its saying its not boosting at all took pipe off the n75 valve and it was boosting but the gauge still said no boost but u can feel it the gauge is working but only gets to 0 and thats it i am at a loss of what to do next eney help will be grait thanks
03-12-2013, 06:19 AM
#18
AudiWorld Senior Member
1 long into intake/inlet rubber hose
1 (down) to turbo compressor housing (seeing 'boost')
1 to wastegate actuator
https://encrypted-tbn1.gstatic.com/i...JWJicG2lVEdKlQ
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.
- blow/suck on long leg: nothing
- blow in any of short legs: open
Correct?
[/QUOTE]
03-12-2013, 06:23 AM
#19
AudiWorld Senior Member
Overboosting?
I installed new N75 (1.8T AEB)
Still seeing 25 psi!
If new N75 (new from ebay) is working, wastegate should open and keep boost low (Giac PC16, would expect 15-18 psi, or?)?
If new N75 is working (VAGcom shows varying duty cycle numbers, but not sure what to expect with Giac tune), but still massive overboost: wastegate not opening, which could be spring, bladder/actuator (new) or the hose from N75 to actuator?
Still seeing 25 psi!
If new N75 (new from ebay) is working, wastegate should open and keep boost low (Giac PC16, would expect 15-18 psi, or?)?
If new N75 is working (VAGcom shows varying duty cycle numbers, but not sure what to expect with Giac tune), but still massive overboost: wastegate not opening, which could be spring, bladder/actuator (new) or the hose from N75 to actuator?
03-17-2013, 08:22 AM
#20
AudiWorld Senior Member
Took the new ebay N75 out. Blow into long leak: NOT tight, leaking.
Put old N75 back in. Boost now controlled.
BUT......
The boost 'swings' by 4 psi or so as soon as I get over 10 psi, at around 0.5 to 1 Hz (one 'swing' per second).
A day later (after completing FSI coil install and some other work), I have the SAME swing (also AEB on Giac PC16, high flow manifold, larger than K04 turbo).
Since I can't change the N75 control in the Giac PC16 tune, what hardware tweaks can I try to get rid of this boost swing, which is very noticeable (not just on the gauge) in lower gears, and can be heard (engine straining at the high boost end of the swing)?
Put old N75 back in. Boost now controlled.
BUT......
The boost 'swings' by 4 psi or so as soon as I get over 10 psi, at around 0.5 to 1 Hz (one 'swing' per second).
A day later (after completing FSI coil install and some other work), I have the SAME swing (also AEB on Giac PC16, high flow manifold, larger than K04 turbo).
Since I can't change the N75 control in the Giac PC16 tune, what hardware tweaks can I try to get rid of this boost swing, which is very noticeable (not just on the gauge) in lower gears, and can be heard (engine straining at the high boost end of the swing)?
I installed new N75 (1.8T AEB)
Still seeing 25 psi!
If new N75 (new from ebay) is working, wastegate should open and keep boost low (Giac PC16, would expect 15-18 psi, or?)?
If new N75 is working (VAGcom shows varying duty cycle numbers, but not sure what to expect with Giac tune), but still massive overboost: wastegate not opening, which could be spring, bladder/actuator (new) or the hose from N75 to actuator?
Still seeing 25 psi!
If new N75 (new from ebay) is working, wastegate should open and keep boost low (Giac PC16, would expect 15-18 psi, or?)?
If new N75 is working (VAGcom shows varying duty cycle numbers, but not sure what to expect with Giac tune), but still massive overboost: wastegate not opening, which could be spring, bladder/actuator (new) or the hose from N75 to actuator?