SOLENOID-MDS
DESCRIPTION
The Multi Displacement System selectively deactivates cylinders 1,4,6, and 7, to improve fuel economy. It has two modes of operation :
- 8 cylinders for acceleraton and heavy loads.
- 4 cylinders for cruising and city traffic.
The main components of the Multi Displacement System are :
- Unique MDS camshaft.
- Deactivating roller tappets.
- 4 control valves/solenoids.
- control valve/solenoid wiring harness.
- oil temp sensor.
OPERATION
Cylinder Deactivation
- Trap an exhaust charge from a normal combustion event
- Normal combustion event
- Don't open the exhaust valve
- Don't open the intake valve
- Piston is an air spring
- Cylinders deactivated in firing sequence
Cylinder Reactivation
- Open the exhaust valve
- Empty the cylinder
- Open the intake valve
- Normal combustion event
- Cylinders reactivated in firing sequence
DIAGNOSIS AND TESTING
The Multi Displacement System has the following detectible issues:
- Solenoid circuit
- Fail to deactivate a cylinder(s)
- Fail to reactivate a cylinder(s)
- Low oil pressure
| CONDITION |
POSSIBLE CAUSES |
CORRECTION |
| MDS does not activate |
1. Low oil pressure |
1. Check for proper
oil pressure |
| 2. Bad oil temp sensor |
2. Replace oil temp sensor |
|
| 3. Malfunctioning MDS Solenoid |
3. Replace Solenoid |
|
| 4. Malfunctioning MDS Tappet |
4. Replace Tappet |
|
| MDS Does Not Deactivate |
1. Low oil pressure |
1. Check for proper oil pressure |
| 2. Bad oil temp sensor |
2. Replace
oil temp sensor |
|
| 3. Malfunctioning MDS Solenoid |
3. Replace Solenoid |
|
| 4. Malfunctioning MDS Tappet |
4. Replace Tappet |
REMOVAL
1. Disconnect the negative battery cable.
2. Remove the intake manifold. (Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANIFOLD - REMOVAL).
3. Remove wiring harness connectors from the MDS solenoids.
4. Remove hold down bolt from MDS solenoid.
5. Remove MDS solenoid.
INSTALLATION
1. Verify that MDS bores are free of debris, before solenoid installation.
2. Install MDS solenoid fully into block.
3. Install hold down bolt and torque to 11 N·m (97 in. lbs.).
4. Reconnect the MDS wiring harness to the solenoids.
5. Install the intake manifold. (Refer to 9 - ENGINE/MANIFOLDS/INTAKE MANIFOLD - INSTALLATION).