Spark Knock/Pings

***UPDATED BY TSB #AT90005, DATED NOVEMBER 1990
On some 1990 300ZX non-turbo models with automatic transmissions, the customer may complain excessive of spark knock (ping). A new ECU is available to reduce this incidence.
When a customer complains of this problem confirm the following:
1. Unleaded premium fuel is being used in the vehicle.
2. All tune specs have been set to proper specifications (timing, idle speed, throttle sensor, etc.).
3. No other faults are present (trouble codes, vacuum leaks, etc.).
4. Verify that the knock occurs under the following conditions:
a. Intake manifold vacuum is between 5.91 - 7.87 in.Hg. (150 - 200 mmHg).
b. Engine is operating at approximately 2000 rpm.
c. Vehicle speed is approximately 60 mph.
5. If all these points have been verified, install the new ECU and confirm that the problem has been eliminated.

MARKET DESIGNATION NEW ECU PART # OLD ECU PART #
California models 2371M-40P60RE 23710-30P13
Federal models 2371M-40P65RE 23710-30P18

***UPDATED BY TSB #92014, DATED FEBRUARY 1992
On some 1990 300ZX models the customer may complain of excessive spark knock (ping). This may be caused by the ignition timing being excessively advanced. It may be impossible to adjust the ignition timing to the proper specifications due to a damaged crank angle sensor and/or cam shaft. It may be necessary to replace the crank angle sensor, left cylinder head and cam shaft. Refer to the TSB for complete information.

��1Spark Knock/Pings:

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