Ignition - Spark Knock, Initial Timing Incorrect

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Classification:
EM92-002

Section:
Engine Mechanical

Reference:
TECHNICAL BULLETIN NTB92-014


Models:
1990 30OZX & 30OZX Turbo

Date:
February 27, 1992


1990 30OZX CRANK ANGLE SENSOR CAUSING DETONATION

(SPARK KNOCK)

This Bulletin amends Bulletin EM91-005 (NTB91-056) dated May 30, 1991, in 1991 Technical Bulletin book, giving additional parts information.


APPLIED MODELS:
1990 300ZX, 30OZX TURBO

APPLIED VIN:
Prior to:
JN1RZ24A-MXO50007 (July 3, 1990)
JN1RZ26A-MXO50002 (July 3, 1990)
JN1CZ24A-MXO50001 (July 4, 1990)
JN1RZ24H-MX500223 (July 20, 1990)
JN1RX26H-MX500046 (July 3, 1990)
JN1CZ24H-MX500082 (July 4, 1990)

SERVICE INFORMATION:

On some 1990 30OZX vehicles, customers may complain of engine detonation (spark knock). The incident may be caused by the initial ignition timing being excessively advanced. If the vehicle has this condition, it may be impossible to adjust the timing to the correct initial specification by turning the crank angle sensor.

The cylinder head assemblies of the incident vehicles may have been improperly machined. This results in the camshaft indexing peg and the crank angle sensor being off-center. The offcenter condition allows excessive force to be applied to the indexing peg which results in damage to the peg. In most cases, but not all, the indexing peg on the camshaft will be damaged causing the incident of advanced ignition timing.

SERVICE PROCEDURE:


Check the crank angle sensor initial ignition timing using a timing light. Note: The CONSULT unit will not give initial timing. If the initial timing is incorrect, make the necessary adjustments.





If the initial ignition timing cannot be set to the proper specification, check for damage to the indexing peg on the camshaft. Damage to the indexing peg will confirm the cause of the incident. In this case, it will be necessary to replace the cylinder head to resolve the incident.

Replace the crank angle sensor and/or camshaft if necessary.


Note:
On some vehicles the incident of advanced ignition timing may not always result from a broken indexing peg. If the initial ignition timing is advanced and cannot be adjusted to the correct specification, then replace the parts as required.





PARTS INFOPMATION:





WARRANTY INFORMATION: