Timing Chain Maintenance: Notes

Fig 1: Check Engine Light

Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.

If the vehicle equipped with 2.0 L turbocharged engine continues the rough driving like competitive running^*1 , the amount of carbon mixed into the engine oil tends to increase. This can possibly cause the timing chain to gradually elongate. To prevent this, the function or logic monitoring the amount of elongation of the timing chain is integrated into the ECM. When the ECM detects the elongation of the timing chain, the warning is shown on the multi-information display of combination meter as shown in the illustration. This gives the driver the information that the visual check of the elongation of the timing chain is necessary. If this warning is continuously neglected, the timing chain can possibly interfere with the other engine components, resulting in the engine damaged.

NOTE: ^*1 : The competitive running means the running that constantly repeats the cycle of the full opened position of the accelerator pedal and the full closed position of the accelerator pedal.

The ECM stores the timing chain conditions as the initial learning value when the timing chain is installed. The ECM stores the amount of elongation of the timing chain in the EEPROM as the current learning value, compared with the initial learning value. The ECM judges that the visual check of the elongation of the timing chain is necessary when the current learning value exceeds the specified value. Thus, use the scan tool MB991958 to always carry out the maintenance of the initial learning value related to the timing chain that is stored by the ECM after the following service.

MAINTENANCE CHART

Service

Maintenance items by scan tool MB991958

Maintenance purpose

ECM replacement

Learned value Read & Save ⁽¹⁾
Write learned value (Changed ECU)⁽¹⁾

The purpose is that the initial learning value regarding the amount of elongation of the timing chain stored by the current ECM is loaded in the scan tool MB991958, and then written into the new ECM. This allows the ECM to appropriately monitor the amount of elongation of the timing chain after the ECM replacement.

Visual check of elongation of timing chain

Learned value reset

The purpose is that the initial learning value stored by the current ECM is initialized after the visual check of the elongation of the timing chain by illuminating the warning lamp, whether or not the timing chain is replaced. This allows the ECM to appropriately monitor the amount of elongation of the timing chain.

Timing chain or engine assembly replaced

Learned value reset

The purpose of this procedure is that the initial learning value stored by the current ECM is initialized when the timing chain or the engine assembly (the timing chain is also replaced with a new one.) is replaced. This allows the ECM to appropriately monitor the amount of elongation of the timing chain.

⁽¹⁾

The visual check of the elongation of the timing chain must be carried out under the following conditions: when the initial learning value cannot be written into scan tool MB991958 from the current ECM because of the ECM malfunction and when the initial learning value cannot be written into the new ECM (Refer to TIMING CHAIN ELONGATION VISUAL CHECK ). If elongated more than the specified length at this time, the timing chain can possibly interferes with the other engine components before the new ECM detects the elongation of the timing chain. The timing chain must be replaced with a new one to prevent engine damage.