Exhaust Gas RECIRCULATION (EGR)
EGR EU4 Markets
| ITEM | DESCRIPTION |
|---|---|
| 1 | HP EGR cooler tube from exhaust manifold |
| 2 | HP EGR valve and actuator |
| 3 | HP EGR cooler by-pass actuator |
| 4 | HP EGR cooler |
| 5 | HP EGR outlet to intake manifold |
EGR EU5 and EU6 Markets
| ITEM | DESCRIPTION |
|---|---|
| 1 | Breather pipe inlet from engine vent module |
| 2 | Turbocharger attachment |
| 3 | HP EGR cooler tube from exhaust manifold
NOTE:
(Cooler tube only connected to engine cooling system on EU6 vehicles)
|
| 4 | HP EGR valve and actuator |
| 5 | HP EGR outlet to intake manifold |
| 6 | Engine coolant connection with cylinder block |
| 7 | LP EGR cooler |
| 8 | LP EGR Valve |
EGR NAS Markets
| ITEM | DESCRIPTION |
|---|---|
| 1 | Breather pipe inlet from engine vent module |
| 2 | Turbocharger attachment |
| 3 | HP EGR tube from exhaust manifold |
| 4 | HP EGR valve and actuator |
| 5 | HP EGR cooler by-pass actuator |
| 6 | HP EGR cooler by-pass actuator |
| 7 | HP EGR outlet to intake manifold |
| 8 | Engine coolant connection with cylinder block |
| 9 | LP EGR cooler |
| 10 | LP EGR Valve |
There are two main external Exhaust Gas Recirculation (EGR) systems that are used on the engine - High Pressure (HP) EGR and Low Pressure (LP) EGR.
EGR is used to cool the combustion in the cylinders by introducing exhaust gases without oxygen (exhaust gas). This in turn allows the use of smaller fuel injections, improving emissions and fuel economy.
The following systems are used for specific markets:
- EU4 markets - use a HP EGR valve and cooler and a cooled EGR tube from the exhaust manifold to the HP EGR valve.
- EU5 markets - use both HP and LP EGR valves. The LP system uses an EGR cooler, there is no cooler for the HP system.
- EU6 markets - use both HP and LP EGR valves. The LP system uses an EGR cooler, there is no cooler for the HP system and a cooled EGR tube from the exhaust manifold to the HP EGR valve.
- North America Specification (NAS) markets - use both HP and LP EGR valves. Both the HP and LP systems use an EGR cooler.
HP EGR
The HP EGR valve is attached to the intake manifold. Exhaust gases are routed to the EGR valve from the exhaust manifold. The EGR valve is cooled using engine coolant in the passenger compartment heater core circuit; this is to protect the electrical components from over-heating. The HP EGR valve controls the amount of EGR exhaust gas flow depending on the Powertrain Control Module (PCM) map. The exhaust gases are passed directly into the intake manifold via a simple EGR pipe on EU5/6 market vehicles. The design of the EGR pipe attachment to the inlet manifold helps mix the exhaust gasses with the main fresh air intake and also insulates the plastic intake manifold from the hot EGR pipe.
On EU4 and NAS market vehicles, a separate EGR pipe attachment is used to connect between the intake manifold and the EGR cooler. The exhaust gasses are passed through the EGR cooler before being passed through the EGR pipe to the intake manifold.
LP EGR
The LP EGR system is used on EU5 and 6 and NAS market vehicles only. The LP system takes exhaust gases from the exit of the catalytic converter and Diesel Particulate Filter (DPF) assembly, and mixes it with the fresh air intake into the turbocharger.
The gases are transported from the catalytic converter and Diesel Particulate Filter (DPF) assembly outlet to the LP EGR cooler via a pipe. The LP cooler has no bypass mode, cools all exhaust gas passing through it. There is a simple mesh filter fitted before the gasses reach the outlet of the cooler that prevents larger particles of soot from entering the turbo charger system. The mesh filter is non-serviceable.
The cooled gases are then directed through the LP EGR valve via a flap valve. The flap valve consists of a tube between the fresh air duct and the turbocharger, with the flap valve covering the EGR inlet, in the centre bottom of the EGR valve. The flap valve opens into the fresh air stream, promoting thorough mixing before the gas enters the turbocharger, and also provides 'suction' via a venturi effect to draw the LP EGR gas through the system.
For additional information, refer to: ENGINE EMISSION CONTROL