Repost Warning. (Credit goes to Mike W@RRE)
Big Complicated Timing Chain Tech Info:
If the vehicle equipped with 4B11-T/C 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 possi¬bly 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.
Timing Chain Warning Indicator:
The ECM stores the timing chain conditions as the 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 learning value. The ECM judges that the visual check of the elongation of the timing chain is neces¬sary when the current learning value exceeds the specified value. Thus, use the scan tool MB991958 to always carry out the maintenance of the learning value related to the timing chain that is stored by the ECM after the following service.
TIMING CHAIN ELONGATION VISUAL CHECK
M1111005200024
NOTE:
When the timing chain elongates more than the specified length, the diagnosis code No. P0012, variable valve timing (VVT) advanced-angle value abnormal, is output. Unless the diagnosis code No. P0012, therefore, is output, the visual check is unnecessary.
NOTE:
Unless the work using the following scan tool MB991958 is correctly carried out due to the malfunction of ECM, carry out the check whether or not the diagnosis code exists.
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Storing the learning value regarding the amount of timing chain elongation before the ECM replacement•
Writing the learning value into the new ECM after the ECM replacement•
1.Remove all the ignition coils.
2.Remove the cylinder head cover.
3.Remove the upper chain guide.
CAUTION
Always rotate the crankshaft clockwise.
4.Rotating the crankshaft clockwise, align the timing mark of camshaft sprocket with the point on the upper plane of cylinder head shown in the illustration. As a result of this, the No.1 cylinder is positioned at the compression TDC.
5.Look at the inside of timing chain case with one eye in the direction of arrow shown in the illustration. Fix the eye line at the point where the top axis line of the chain elongation indicator at the front side of timing chain case is overlapped with that of the chain elongation indicator at the reverse side of timing chain case.
6.Check the end top point "A" of timing chain cross section surface and the point of chain elongation indicator which is fixed in Step 5. When the end top point "A" of timing chain is positioned at the left-hand side of chain elongation indicator, it is unnecessary to replace the timing chain because the timing chain is within the specified length. When the end top point "A" of timing chain is positioned at the right-hand side of chain elongation indicator, it is necessary to replace the timing chain because the timing chain elongates more than the specified length.
7.Install the upper chain guide. CAUTION
Completely clean the old FIPG remaining in the clearance between the mating parts.
Install the cylinder head cover within 3 minutes of applying the liquid gasket.•
8.Apply a 4 mm diameter bead of liquid gasket to the point shown in the illustration.