No boost on turbo

Really needs VCDS scan to see if there are any other fault codes.
You initial code indicates N239 valve, which as @audifan suggests controls the anti-shudder function, so it may be worth checking the small pipes connected to this and N239, here's a link showing the arrangement. Perhaps the valve is not fully opening and it's restricting the airflow and thus the engine power?
 
Proghound said:
Sorry I can't help on the boost issue but I can tell you that changing the item pictured isn't going to get you very far. That's the CCCU for the door locks, windows, alarm, rear PDC etc.
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Thank you for the heads up save me some messing about I’ll just check the boost pipes
 
Herb06 said:
Iv add turbo changed egr value replace when you turn the car off you can hear the n75 trying to suck air in All so change the n75 off a Audi a2 that is running fine iv changed all the sensors map check the boost pipes there fine (only thing iv not done is change the small pipes that are coming off the N75 ?? )
Can any one help
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Could be a sticking dump valve it’s internal to the exhaust manifold but is air operated small pipe from n75 valve
 
Going to change all the small pipes off the N75/N239 & see where that gets me message back at the weekend and think you to you all ?
 
Catnip64 said:
Really needs VCDS scan to see if there are any other fault codes.
You initial code indicates N239 valve, which as @audifan suggests controls the anti-shudder function, so it may be worth checking the small pipes connected to this and N239, here's a link showing the arrangement. Perhaps the valve is not fully opening and it's restricting the airflow and thus the engine power?
Click to expand...
This sounds like it yes, staved of air. Vcds can show boost expected and actual too
 
Herb06 said:
Going to change all the small pipes off the N75/N239 & see where that gets me message back at the weekend and think you to you all ?
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Just to add my own experience, I got the exact same issue after a cambelt and water pump change too, on my first A2. All was well before that. I wasted ££££££’s chasing down the issue and never found the cause. I‘m guessing something the garage has done (not necessarily their fault, boost pipe that was failing anyway and disturbed maybe ?) during the cam belt change caused the boost leak. As soon as I tried to go over 3000rpm or put too much pressure on engine going uphill, boost would fail and only switching off the ignition and restarting the engine would fix it. I think you are on the right track now and watching this thread with interest. Please don’t forget to let us know if you find the cause!
 
froggy said:
Just to add my own experience, I got the exact same issue after a cambelt and water pump change too, on my first A2. All was well before that. I wasted ££££££’s chasing down the issue and never found the cause. I‘m guessing something the garage has done (not necessarily their fault, boost pipe that was failing anyway and disturbed maybe ?) during the cam belt change caused the boost leak. As soon as I tried to go over 3000rpm or put too much pressure on engine going uphill, boost would fail and only switching off the ignition and restarting the engine would fix it. I think you are on the right track now and watching this thread with interest. Please don’t forget to let us know if you find the cause!
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I will let everyone no the out come of this ?
 
Hi everybody i just need to no should there be power going to the N75 when the engine on tick over ??
Iv got the a2 booked in at the garage this Wednesday 02/02/2022 to do the vacuum pipe. I was going to do it myself but it looks a-bit tricky getting my hands round to the back of the engine
 
Yes the valve is electrically operated. It varies the amount of turbo pressure that is either vented or sent to the turbo "dump valve" thus regulating the level of boost. Although at idle no boost is required so N75 probably just venting any pressure.
 
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If you can rig up full vcds you can monitor boost pressure at idle and through the rev range. Date is shown as actual oostende vs what's expected so you can see if there are sudden spikes in boost or delays etc which helps give you clues. Do you have a tdi 90 or 75 bhp? These have different turbos with different issues.
 
audifan said:
Yes the valve is electrically operated. It varies the amount of turbo pressure that is either vented or sent to the turbo "dump valve" thus regulating the level of boost. Although at idle no boost is required so N75 probably just venting any pressure.
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Thank you so there should be power to the N75 on tick over
 
CrispyEdd said:
If you can rig up full vcds you can monitor boost pressure at idle and through the rev range. Date is shown as actual oostende vs what's expected so you can see if there are sudden spikes in boost or delays etc which helps give you clues. Do you have a tdi 90 or 75 bhp? These have different turbos with different issues.
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75 bhp I have in back of my head I will have to go get the vcds of a friend and do a check what should the boost pressure be ?? Please
 
Display zone
Readout​
Specification for engine code AMF, BHC​
Specification for engine code ATL​
-1-​
Engine speed​
2800 ... 3200 rpm​
2800 ... 3200 rpm​
-2-​
Specification (charge pressure)​
1800 ... 2100 mbar​
2100 ... 2400 mbar​
-3-​
Actual (charge pressure)​
1700 ... 2200 mbar​
2000 ... 2500 mbar​
-4-​
Signal ratio of charge pressure control solenoid valve -N75-​
… %​
… %​
 
Update iv done everything I can do now Change the vacuum lines change N75 the mechanic saying it’s a cheap fuel filter (I said to the mechanic) thinking about it when I add the a2 service the fuel filter was £26 he reply with ??? Maybe injectors then
It’s add
New turbo
New n75
New egr
New vacuum pipes
New maf Sensor
Plus a sensor on the inter cooler

Just something I want to ask people out there if I had a stage 1 map done on it would it pick the fault up that is wrong with the Audi it’s done 122.000 does anyone think the dpf would be blocked with the mileage it’s done ???
 
Just going back to top of thread, have you been able to check the anti shudder/throttle valve operation is okay? Not getting stuck? Wasn't the original code in that area? May just need a clean out or internal cog rebuild.
 
Its a 75 AMF so different set up to the BHC and ATL. Anti shudder only closes to turn off engine then springs fully open again. What is the EGR valve like? Has the cam belt been changed and mistimed the engine? Has someone been playing with the TV which is VERY dangerous unless you know exactly what you are doing? What condition is the exhaust in and is it free of major blockages? Is the exhaust manifold intact? Reverting back to standard will rule out or prove the map.

As they say a little knowledge is a dangerous thing both for owners and "mechanics".

Where is the VCDS scan result?????????????
 
kp 115 said:
Could be a sticking dump valve it’s internal to the exhaust manifold but is air operated small pipe from n75 valve
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Have you checked the dump valve operation, mine was difficult to move by hand let alone air pressure, if this is letting air out you won’t get the charge pressure required = poor pick up & performance .
VCDS scan will show charge pressures etc & could pin point fault.
Hope that helps
Keith.
 
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