LeSabre V8-307 5.0L VIN Y 4-bbl (1984)
Spark Plug: Customer Interest
Engine - Cold Weather Spark Plug Fouling
Bulletin 84-6E-7
Date Jan. '84
Ref. No. 84-091-6E
SUBJECT:
SPARK PLUG CHANGE
MODELS AFFECTED: 1984 LESABRE, ELECTRA & RIVIERA WITH 5.0L V-8 ENGINE
Buick 5.0L V-8 engines built after 10/1/83 and prior to 4/1/84 will be equipped with R46SZ spark plugs with a gap of .060 inches. This change was
made to reduce cold weather spark plug fouling. The emission label will indicate the correct spark plug as R46SX gapped at .080 inches. Whenever
spark plug replacement becomes necessary, the R46SX should be used.
However, if the numbers seen are continually increasing such as 60, 90, 118, 150, 195, 239, 10, 40 this indicates that the ECM is seeing a signal and is
retarding the timing in large amount (19~) which will usually set a code and is most likely an electrical disconnect to or from the ESC module. Small
number increases indicate smaller or very little retard is taking place.
To locate the noise causing spark retard, the vehicle should be run on a lift at the speeds the most count changes were seen, and listen closely from
underneath to the engine and transmission for any unusually loud knocks, pecks, or buzzing such as rocker arms, lifters, transmission-front pump
pressure regulator valve, etc.
If retard is still seen with detonation sensor disconnected, retard is due to a false signal on wire from knock sensor to controller or ESC connections.
Rerouting wire away from other wires, such as spark plugs, etc. is required.
Diagnosis without ALCL Scan Tool including 1983-1/2 Regals:
Perform CCC circuit diagnostic circuit check to determine if any trouble codes are present. If any codes are present, use of the appropriate diagnostic
chart and correction is required before proceeding.
If no trouble codes are present, drive the vehicle to determine if a performance condition exists (compare with another known good-like vehicle for
comparison, if required). If a driveability condition does exist, Code 43 Chart voltage at ECM terminal "L" low, should be used first. If no trouble is
found, using the Code 43 Chart, disconnect the detonation sensor, and drive the vehicle again. If improvement is noted, the problem could be engine or
transmission noise being picked up by the detonation sensor.
To locate the noise, the vehicle should be run on a lift at the speeds the performance was at its worst, and listen closely from underneath to the engine
and transmission for any unusually loud knocks, pecks or buzzing such as rocker arms, lifters, trans-front pump pressure regulator valve buzz, etc.
If a performance condition still exists with the detonation sensor disconnected, engine timing may still be retarding due to a false signal on wire from the
knock sensor to the electronic spark controller. Rerouting wire away from other wires, such as spark plugs, etc, is required.
The following components should also be checked, distributor shaft end play, camshaft timing, spark plug wires and distributor cap.
