Wastegate Control Lines
Thread Starter
Audiworld Junior Member
Joined: Jul 2011
Posts: 17
Likes: 0
Wastegate Control Lines
After much diagnosing I've found that a wastegate control line is leaking. I was getting actual boost pressures that were exceeding the requested boost which resulted in the ECU cutting the throttle (yea!).
Cycled the N75 with the VAG-COM (click...click...click). Pulled the N75 and blew through the pressure supply (bottom) port and air came out the correct side (boost pressure to open wastegates).
Compressed air to check wastegate operation (figuring I'd hear them actuate with 10 psi) and "whoosh" from a leak but, for the life of me, I cannot see the leak.
Going to check sides tomorrow (got dark outside and had to put kids to sleep).
Big question is - To replace/repair the lines how much disassembling as I'm looking at? I've had this beast about a month and can't even see the turbos. Have the lower skid plates removed and most covers. I'd be happy if someone told me how to even see the wastegate servos.
Any help appreciated.
Cycled the N75 with the VAG-COM (click...click...click). Pulled the N75 and blew through the pressure supply (bottom) port and air came out the correct side (boost pressure to open wastegates).
Compressed air to check wastegate operation (figuring I'd hear them actuate with 10 psi) and "whoosh" from a leak but, for the life of me, I cannot see the leak.
Going to check sides tomorrow (got dark outside and had to put kids to sleep).
Big question is - To replace/repair the lines how much disassembling as I'm looking at? I've had this beast about a month and can't even see the turbos. Have the lower skid plates removed and most covers. I'd be happy if someone told me how to even see the wastegate servos.
Any help appreciated.
AudiWorld Senior Member
Joined: Dec 2010
Posts: 826
Likes: 2
You can see them through the wheel wells with the liners removed. Working on them is a little harder. Grow eyes on the ends of your fingers as most turbo work is done by feel due to their tight location.
The best is if you ever have to replace a turbo. This requires a partial to full removal of engine.
Audi wasn't thinking of ease of maintenance when they designed the 2.7t engine bay.
The best is if you ever have to replace a turbo. This requires a partial to full removal of engine.
Audi wasn't thinking of ease of maintenance when they designed the 2.7t engine bay.
Thread Starter
Audiworld Junior Member
Joined: Jul 2011
Posts: 17
Likes: 0
Getting to wastegate control line splitter hard enough
I've got to at least get to the splitter so I can figure out which side has the leak (if it's only one side). Maybe I'll get lucky and it will be near the tee and easier to access but I'll expect the worse.
I did see the turbo when the sun came out but it's way up in there and I only saw the actuator arm, not the servo.
I did see the turbo when the sun came out but it's way up in there and I only saw the actuator arm, not the servo.
Thread Starter
Audiworld Junior Member
Joined: Jul 2011
Posts: 17
Likes: 0
Found (sortof)
The leak - big - is on the passenger side. The drivers side holds pressure.
Pulled loads of crap out of the way from the engine compartment but, alas, that didn't get me anywhere.
Going to pull the wheel and inner fender liner next to see if that gets me any closer.
Probably going to fabricate my own line to replace/bypass the original as I can't see over $100 for a low pressure line. Must have some stainless tubing laying around somewhere.
Getting ahead of myself - have to actually get a hose connected to the wastegate servo first before I can think of bypass.
Fortunately it is only 90F+ and about 80% humidity out right now.
Onwards and upwards.
Pulled loads of crap out of the way from the engine compartment but, alas, that didn't get me anywhere.
Going to pull the wheel and inner fender liner next to see if that gets me any closer.
Probably going to fabricate my own line to replace/bypass the original as I can't see over $100 for a low pressure line. Must have some stainless tubing laying around somewhere.
Getting ahead of myself - have to actually get a hose connected to the wastegate servo first before I can think of bypass.
Fortunately it is only 90F+ and about 80% humidity out right now.
Onwards and upwards.
Thread Starter
Audiworld Junior Member
Joined: Jul 2011
Posts: 17
Likes: 0
Could be diaphragm
Had horrible thought that the leak could be in the diaphragm. I need to do some real work and wait until I get the inner fender liner off so I can do further investigation.
What I wouldn't do for a mechanics endoscope.
What I wouldn't do for a mechanics endoscope.
Thread Starter
Audiworld Junior Member
Joined: Jul 2011
Posts: 17
Likes: 0
Well, am not going to be able to get to actuator without supporting engine and removing mount.
It is just way to tight in there to get to "nipple" on actuator let alone get clamp off/ on.
At least I sighted the thing.
It is just way to tight in there to get to "nipple" on actuator let alone get clamp off/ on.
At least I sighted the thing.
AudiWorld Member
Joined: Mar 2011
Posts: 222
Likes: 0
Hmm... back in the day, I used to intentionally bleed (in a controlled amount) a little bit of the pressure from the wastegate in order to increase the overall boost level. This was on my Eagle Talon Tsi AWD.
Is it possible to do the same thing in the newer turbocharged Audi vehicles?
Is it possible to do the same thing in the newer turbocharged Audi vehicles?
Trending Topics
Thread Starter
Audiworld Junior Member
Joined: Jul 2011
Posts: 17
Likes: 0
Boost Control
It might increase your boost BUT the ECU will see that actual boost is more than requested boost and reduce the throttle angle.
This exercise has taught me a lot about the way charge pressure is controlled by the stock ECU.
You could chip the vehicle but then you would need to beef up the intake to deal with the increased boost. Noticed that most of the problems (broken components, etc.) are the result of trying to wring more power out of the engine than it was designed for.
I'm not looking for uber-performance, just want the stock to work correctly. The current state results in power comparable to a Subaru.
This exercise has taught me a lot about the way charge pressure is controlled by the stock ECU.
You could chip the vehicle but then you would need to beef up the intake to deal with the increased boost. Noticed that most of the problems (broken components, etc.) are the result of trying to wring more power out of the engine than it was designed for.
I'm not looking for uber-performance, just want the stock to work correctly. The current state results in power comparable to a Subaru.
AudiWorld Stories
Bringing Audi to Life for Audi Fans
Top 10 Most Expensive Audis Ever Sold on Bring-A-Trailer
Brett Foote
10 Audi Features & Options We Miss the Most!
Joe Kucinski
Audi Recreates Crazy-Looking Speed Record Breaker From 1935
Verdad Gallardo
Coachbuilder Recreates the 1995 Audi TTS Concept
Verdad Gallardo
Every Audi V10 Car Ranked!
Joe Kucinski
9 Audi Designs That Aged Like Fine Wine
Verdad Gallardo
2026 Audi Q5 Buyer's Guide (Every Model Explained)
Brett Foote
Ranking Every Current Audi 'S' Model From Worst to First!
Joe Kucinski
10 Best Audis That are FINALLY LEGAL to Import to the U.S.!
Joe Kucinski
AudiWorld Senior Member
Joined: Jun 2006
Posts: 611
Likes: 2
thrse wastegstes operate on vaccum for boost, and boost for opening and bypassing the turbo hot section
run your boost line to right after the throttle body evap line.
2500 psi at the throttle body on a stock setup.
i today did a hitachi to bosch conversion, what a waste, damm bosch reads 25 g/s at 800 rpm, and if i punch it it goes over 400 g/s second at 1800 mbar. i even rigged the hitachi into the bosch housing, even worst and it drove like poo.
but i did find after using a ultimeter to the dbw housing that pin 6 controls load for the whole car.
does anybody know which one is for throttle cut???
i guess i will just snip 1 by 1 untill found.
run your boost line to right after the throttle body evap line.
2500 psi at the throttle body on a stock setup.
i today did a hitachi to bosch conversion, what a waste, damm bosch reads 25 g/s at 800 rpm, and if i punch it it goes over 400 g/s second at 1800 mbar. i even rigged the hitachi into the bosch housing, even worst and it drove like poo.
but i did find after using a ultimeter to the dbw housing that pin 6 controls load for the whole car.
does anybody know which one is for throttle cut???
i guess i will just snip 1 by 1 untill found.
Thread Starter
Audiworld Junior Member
Joined: Jul 2011
Posts: 17
Likes: 0
choptt - not sure about whether the wastegates are held shut by the spring until boost pressure (via the N75) opens them or if vacuum is require (again, via N75) to keep them shut.
However, this is about fixing the wastegate control line and I'm elbows into it. Front lock carrier is off and I can see the damn line now. Too late to pressurize and see if that is where the leak actually is.
Fortunately, I bought this thing used and, being cautious, am replacing the timing belt/water pump/tensioners so the lock carrier had to come off anyway (just passed 100K miles). Kit will arrive tomorrow.
Unforseen issue - DIY writeups and Bentley failed to mention transmission cooler line removal. Again, I already had a new transmission filter on hand. Too bad it appears to be a PITA to fill the system properly.
Tomorrow will start working to get the motor mount bracket off so I can actually access the actuator and put on home made line. Too bad the local auto parts stores are light when it comes to braided silicone line. Think I'll just route the line such that it won't experience the heat from the exhaust and, if I ever have to completely pull the engine, I'll fabricate SS lines myself.
Onwards and upwards.
However, this is about fixing the wastegate control line and I'm elbows into it. Front lock carrier is off and I can see the damn line now. Too late to pressurize and see if that is where the leak actually is.
Fortunately, I bought this thing used and, being cautious, am replacing the timing belt/water pump/tensioners so the lock carrier had to come off anyway (just passed 100K miles). Kit will arrive tomorrow.
Unforseen issue - DIY writeups and Bentley failed to mention transmission cooler line removal. Again, I already had a new transmission filter on hand. Too bad it appears to be a PITA to fill the system properly.
Tomorrow will start working to get the motor mount bracket off so I can actually access the actuator and put on home made line. Too bad the local auto parts stores are light when it comes to braided silicone line. Think I'll just route the line such that it won't experience the heat from the exhaust and, if I ever have to completely pull the engine, I'll fabricate SS lines myself.
Onwards and upwards.