Engines, General Modifications

Fig 1: Identifying General Engine Modifications

Courtesy of VOLVO CARS CORPORATION

5 and 6 cylinder diesel and gasoline engines

Generator

The first ramp up of the charge current (after start) is always completed, irrespective of the engine speed (rpm). This increases the engine load successively, preventing sudden loads. Otherwise the ramp up characteristic of the charge current is maintained.

Previously the ramp up was interrupted and full charge current was permitted when the generator speed exceeded ≈ 3400 rpm, even during the first ramp up.

Function:

The charge current is 0 A until the generator speed has reached ≈ 1450 rpm. The charge regulator continues to maintain the charge current at 0 A for a few further seconds
Ramp up then begins. For a number of seconds the charge current increases linearly from 0 % to 100 % of the maximum power handling capacity. If the requirement is less than the power handling capacity, it takes less than 6 seconnds to reach the controlled condition.

General:

All 5 cylinder engines have generators with freewheels
6 cylinder engines have fixed pulleys
All 5 and 6 cylinder engines have 140 A generators.

Unique to the XC90:

The 5 cylinder engines (diesel and gasoline) with rear air conditioning have 160 A generators
The 6 cylinder engines have 160 A generators.

5 and 6 cylinder gasoline engines

Pistons

All engines (except B5204TX, B5234TX and B5244TX) have pistons with the mantles coated with graphite. This reduces noise and lowers the friction between the piston and the cylinder, particularly when cold starting and under large loads at low engine speeds. Also improves resistance to scoring.

Pulsation damper fuel rail

The engines have a pulsation damper, ATD (Air Tube Damper), in the fuel rail. The pulsation damper is filled with air and helium. Helium is used during manufacture to check for leaks.

Combined temperature/pressure sensor for intake air (turbocharged engines only)

The temperature/pressure sensor, T-MAP (Temperature/Manifold Absolute Pressure), is on the outlet side of the charge air cooler (CAC).

The sensors work according to the previous principles.

There are new resistance values for the temperature sensor.

5 cylinder naturally aspirated and turbocharged engines

The flame trap has a labyrinth which efficiently separates oil from the crankcase vapors before they are returned to the intake manifold. Does not apply to Bi-Fuel cars.

The camshaft toothed belt is reinforced to increase service life. The belt tensioner has a new gasket to ensure an optimal seal.

B6294T and B6294S2

The diameter of the gear drive on the coolant pump has been reduced. The number of teeth has been reduced from 21 to 17. The pump operates at a higher speed, improving the flow and therefore engine cooling.

New tension pulley for the camshaft. The increased diameter compensates for the smaller gear drive for the coolant pump. The timing belt is unchanged.

B5244S/S2

CVVT (Continuous Variable Valve Timing) only for the intake camshaft. Change over angle CVVT intake = 60 crankshaft degrees
A new manifold gives improved torque at low engine speeds
Only an under floor catalyst with two ceramic monoliths and integrated muffler
New ETA (Electronic Throttle Actuator)
Start is based on the Wide Range concept
Electrical cooling fan for the control module box. The fan starts when the temperature reaches ≈ +70 °C and stops at ≈ +65 °C. The temperature sensor in the engine control module (ECM) is used as a reference
The connection nipple for the crankcase ventilation at the intake manifold has been modified to provide more even distribution of the crankcase vapors between the cylinders. A positive temperature coefficient (PTC) element prevents freezing.

Resonator

There is a resonator on the hose between the mass air flow (MAF) sensor and the ETA (Electronic Throttle Actuator). This is to satisfy European legal requirements for vehicle sound levels. By modifying the unfavorable frequencies which occur at high engine speeds, the sound levels of the intake and exhaust systems are reduced.

When the pulses affect the measurement function of the mass air flow (MAF) sensor, software in the engine control module (ECM) compensates for this. Because the pulses have been reduced, the software has also been modified from previous engine control modules (ECM).

If the resonator is removed, the signals from the mass air flow (MAF) sensor will be incorrectly interpreted by the engine control module (ECM).

B5204T4, B5234T7, B5244T9

General

Engine management system Bosch 7.01
Bosch ETA (Electronic Throttle Actuator)
The location of the evaporative emission system (EVAP) valve has been moved to the engine
CVVT only for the exhaust camshaft
Leak diagnostic based on the overpressure principle. Applies only to USA.

D5244T/T2

XC90

The fuel pressure sensor and safety valve have changed place on the fuel rail for increased safety in the event of a collision
Unique software due to EGR calibration, weight and to ensure a more rapid response during "take off".

All D5244T/T2

The manifold absolute pressure (MAP) sensor on the intake manifold has been withdrawn and replaced by a combined T-MAP sensor. Only the MAP sensor is used. The signal characteristic is unchanged
Adapted oil drain pipe for the turbocharger (TC)
Modified intake manifold for the coolant pump.