Automotive Audi a3 2.0 tdi s line 08. Turbo is not producing any power and fuel economy has reduced. Engine is running normal with no unusual noises. Ran a diagnostics test and found no faults.

SOURCE: turbo over boost on audi

I can help you to fix this problem. "Fault code: P1557 - Turbo Boost pressure control exceeded"
But I need some info from your engine:
- what type of engine do you have (engine code: ex.ALH, AJM, AWX, ...) or power in kW (PS)
- how many km (miles) are your car?

My e-mail adress is: [email protected]

SOURCE: no acceleration,audi 1.8t,runs like no boost

have you tried cleaning out the throttle body as i had a similar problem and this worked

John Weathers

• 409 Answers
• Posted on May 13, 2009

SOURCE: A4 2.0 TDI. Rough idle

You could have a bad air flow sensor. Do you also have a lack of power??

SOURCE: hi my audi 1.9 tdi is losing power badley the

If somebody replaced the turbocharger with a new one, you must check up all command vacuum lines, the entire air intake system (air pressure pipes, intercooler, connections, EGR - throttle vane, ...), and also turbocharger and EGR command solenoid valves (three pieces). Could be also MAF sensor defective! Here you have the vacuum air pipes connection picture for Audi A4 1.9 TDI (AJM engine):
Please Rate my Response! Thanks!

SOURCE: boost(?) problem audi tt

It is probably either the N75 valve(Diverter Valve) or the wastegate actuator. Usually a significant boost leak will set a DTC, still check all hoses and clamps.

A bad wastegate actuator or flap would cause no boost but not necessarily the air-sound.

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Testing N75

Air Bypass Valve: Testing and Inspection
With Generic Scan Tool
Wastegate Bypass Regulator Valve, Checking
Recommended special tools and equipment e.g.:
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
Test sequence
- Switch ignition off.
- Disconnect connector at solenoid valve for boost pressure regulation.
- Measure resistance between terminals of valve.
Specified value: 25...35 Ohm
If specified value is not obtained:
- Replace Wastegate Bypass Regulator Valve -N75-.

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Testing N249

Exhaust Bypass Valve: Testing and Inspection
With Generic Scan Tool
Recirculating Valve For Turbocharger, Checking
NOTE: Valve opens between connection to intake manifold and connection to deceleration shut-off valve with no voltage. Connection to vacuum
reservoir is closed.
Test sequence
- Switch ignition off.
- Disconnect connector from Recirculating valve for turbocharger -N249-.

- Measure resistance between terminals of valve.
Specified value: 27...30 Ohm
If specified value is not obtained:
- Replace Recirculating valve for turbocharger -N249-.
If specified values are obtained:
- Connect test box to control module wiring harness, connect test box for wiring test.

- Check wire between test box socket 105+2-pin connector terminal 2 for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
- Also check the wire for short circuit to B+ and Ground (GND).
If no malfunctions are found in wire:
- Check wire between 2-pin connector terminal 1 and the Fuel Pump (FP) Relay -J17- for open circuit according to wiring diagram.
Wire resistance: max: 1.5 Ohm
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).

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To test the wastegate, locate the wastegate linkage rod and verify that there is no play and that it is closed. You can apply compressed air to the actuator to see if it opens and closes. (not more than 30 psi)

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Vehicle: Vacuum and Vapor Hose Diagrams
System Diagram
Vacuum Diagram
1 From fuel tank
2 EVAP canister
- with Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-
3 Check-valve for EVAP canister
- Between EVAP canister and intake manifold before turbocharger Installation position (light/dark side): Arrow points in direction of flow, as
shown
4 Turbocharger
5 Pressure unit for boost pressure regulation
6 Mechanical recirculation valve
7 Brake booster
8 Check-valve
- Between brake booster and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
9 Wastegate bypass regulator valve -N75-
10 Mass Air Flow (MAF) sensor -G70-
11 Air cleaner housing
12 Pressure control valve for crankshaft housing ventilation
13 Vacuum reservoir
- Bolted on at cylinder head
14 Charge air cooler
- With charge air pressure sensor -G31-
15 Fuel pressure regulator
16 Throttle valve control module -J338-
17 Intake manifold
- With Intake Air Temperature (IAT) sensor -G42-
18 Crankcase ventilation
19 Check-valve
- Installation position (light/dark side): Arrow points in direction of flow, as shown
20 Recirculating valve for turbocharger -N249-
- Component location Fig. 1
21 Check-valve
- Between EVAP canister and intake manifold
- Installation position (light/dark side): Arrow points in direction of flow, as shown
22 Charge air cooler