Engines of the Audi TT MK1 (8N)

1.8 L turbo (150–240 hp) and 3.2 L V6 250 hp with transverse engine mounting.

The Audi TT was offered with two types of engines:

  • a 1.8L turbo in-line four-cylinder engine
  • a naturally aspirated 3.2L six-cylinder engine with a 15° V angle

The four-cylinder turbo engine, initially offered in 180 hp and 225 hp, was subsequently offered in different versions, offering powers of 150 hp, 163 hp, 190 hp and even 240 hp for the quattro sport version. These variations made it possible to meet different needs and requirements in terms of performance while maintaining the same basic architecture. The different versions of each of these declinations correspond to the evolutions necessary to comply with the changes in the anti-pollution standards.

The six-cylinder V engine, which appeared in 2003, offered a power of 250 hp.

These two types of engines were installed in a transverse position, which made it possible to optimize the space available in the engine compartment and improve the handling of the car.

4-cylinder in-line 1.8L Turbo 180cv hp

4-cylinder in-line 1.8L Turbo 150 to 190 hp

4-cylinder in-line 1.8L Turbo 225 hp

4-cylinder in-line 1.8L Turbo 225 hp

V6 at 15° 3.2L 250 HP

V6 at 15° 3.2L 250 hp"

Identification and main differences

The evolutions of the engines mainly respond to the evolutions of pollution standards.

Type Start date End date Emissions standard Turbo Catalyst control Variable valve timing Secondary Air System
1.8 L Turbo - 150 hp
AUM January 2001 June 2006 Euro 4 KO3S ok ok ok
1.8 L Turbo - 163 hp
BVP September 2005 June 2006 Euro 4 KO3S ok ok ok
1.8 L Turbo - 180 hp
AJQ October 1998 August 2000 Euro 2 + D3 KO3
APP September 1999 September 2000 Euro 2 + D4 KO3 ok ok
ARY September 2000 Mai 2005 Euro 3 KO3S ok ok ok
AUQ September 2000 June 2005 Euro 4 KO3S ok ok ok
ATC 2000 2000 TLEV KO3 ok ok
AWP 2001 2005 LEV KO3S ok ok ok
1.8 L Turbo - 190 hp
BVR September 2005 June 2006 Euro 4 KO3S ok ok ok
1.8 L Turbo - 225 hp
APX October 1998 August 2001 Euro 2 +D3 KO4 ok
BAM September 2000 September 2005 Euro 3 KO4 ok ok
AMU October 1998 2002 TLEV KO4 ok ok
BEA 2003 September 2005 LEV KO4 ok ok ok
1.8 L Turbo - 240 hp
BFV March 2005 June 2006 Euro 3 KO4 ok ok
3.2 L Atmospheric - 250 HP
BHE July 2003 June 2006 Euro 4 - ok ok ok
BPF Mai 2004 Mai 2006 nc - ok ok ok

Catalyst control

Variable valve timing

G39 - Lambda probe upstream of the catalyst
G130 - Lambda probe downstream of the catalyst

As part of the Euro 3 standard, an additional lambda probe (G130), located downstream of the catalyst, has been integrated into the exhaust system:
- The probe G39 upstream of the catalyst is used for air/fuel (wealth) dosing.
- The probe G130 downstream of the catalyst is used to control the operation of the catalyst.

During the diagnosis, the voltages of the probes upstream and downstream of the catalyst are compared by the motor control unit. We are talking here about a relationship between probe upstream and probe downstream of the catalyst.
If this ratio deviates from its set range, the engine management detects a malfunction of the catalyst. When the conditions of a fault are met, the fault memory stores the corresponding fault code.

The lambda control of the engine takes place even in case of failure of the probe downstream of the catalyst. Only the function of the catalyst can no longer be controlled in case of failure of the probe.
In the Motronic, control of the operation of the upstream catalyst probe is also eliminated.

Variable valve timing

Variable valve timing

Variable valve timing

Variable valve timing was introduced to maintain engine power and torque while meeting the Euro 3 standard.

The valve timing system adjusts the intake valve opening and closing times according to engine speed and load, making the most of the advantages of the different camshaft overlap settings.

Intake camshaft timing is varied through the timing chain. A hydraulic piston in the adjuster changes the angular position of the intake camshaft relative to the exhaust camshaft.

At idle, the valve timing is in its basic position, favouring power.
From 1,300 rpm, the valve timing moves to the retarded position, favouring torque.
Finally, from 3,600 rpm, the valve timing returns to its basic position to favour power again.

Secondary Air System

Secondary Air System

Secondary Air System

During the cold start phase, the proportion of unburned hydrocarbons is higher in the exhaust gases.

The secondary air injection system infuses air downstream of the exhaust valves to enrich the exhaust gases with oxygen.
This allows post-combustion of unburned hydrocarbons in the exhaust gases, thus improving their composition.
In addition, the working temperature of the catalyst is reached more quickly thanks to the release of heat attributable to this post-combustion.

As long as the secondary air injection system is operating, the pressure capsule of the boost pressure control valve, controlled by the valve N112, acts on the turbocharger waste-gate valve.
The exhaust gas flow is derived, not passing through the turbine wheel, up to the upper load range.

Secondary air injection valve

N112 - Secondary air injection valve

The secondary air injection valve is an electro-pneumatic valve, which is controlled by the Motronic control unit and controls the combined valve.
For the opening of the combined valve, it releases the depression from the intake tubing.
For closing, it releases atmospheric pressure.

Secondary Air Pump

V101 - Secondary air pump

The J299 secondary air pump relay operated by the Motronic controller switches the current for the V101 secondary air pump motor. The fresh air mixed with the exhaust gases is sucked in by the secondary air pump from the air filter housing and released by the combined valve.