Mercury MerCruiser MCM 454 Mag MPI Service Manual page 562

SERVICE MANUAL NUMBER 23
Diagnostic Trouble Codes for the MEFI 3 454 cid (7.4L) / 502 cid (8.2L) Engines
Number
Index
90-861326--1 MARCH 1999
Downloaded from https://needmanual.com/
Code
Connection
14 ECT high
15 ECT low
21 TPS high
22 TPS low
23 MAT high
25 MAT low
33 MAP high
34 MAP low
EST open (GM
41
distributor only)
42 EST grounded
Continuous
43
knock
44 No knock
FUEL INJECTION SYSTEM TROUBLESHOOTING
Conditions
Minimum run time (10 sec)
Sensor output high (cold) > 240
counts
Minimum run time (10 sec) sensor
Sensor output low (hot) < 7 counts
Sensor output high (> 250 counts)
anytime or, skewed high ( > 70) @
< 700 rpm and < 70 kpa for at least
5 seconds
Sensor output low (< 4 counts)
anytime
Minimum run time (10 sec)
Sensor output high (cold) > 253
counts
Minimum run time (10 sec) sensor
Sensor output low (hot) < 7 counts
kpa > 80 and tps < 5% and rpm >
500 for at least 5 seconds
kpa < 14 and tps > 5% and rpm
<300 for at least 0.5 seconds
Ignore first 20 spark events requires
10 faults to set code
Ignore first 20 spark events requires
10 faults to set code
Must have continuous knock retard
for at least 30 seconds
After 513 tdc knock free events, rpm
> 3000 and MAP > 70 and filtered
sensor noise < 0.14 volts
Comments
Open circuit
Faulty sensor
Short circuit
Faulty sensor
Open circuit,
WOT Faulty sensor
No reference
ground
Short circuit
Faulty sensor
No reference
voltage
Open circuit
Faulty sensor
Short circuit
Faulty sensor
Open circuit
Faulty sensor
No Reference
ground
Short circuit
Faulty sensor
No reference
voltage
Open circuit
Faulty ignition
module
Short circuit
Faulty reference
pickup
Incorrect base
timing
Faulty knock sensor
Disconnected
sensor
Broken/open circuit
Faulty knock sensor
Page 5D-3