Engine Control Operation Chart; Troubleshooting Guide - Mazda MX-5 1990 Workshop Manual

F
TROUBLESHOOTING GUIDE
TROUBLESHOOTING GUIDE
ENGINE CONTROL OPERATION CHART
Input Devices and Engine Conditions
INPUT
DEVICES
ENGINE
CONDITIONS
CRANKING
-COLD ENGINE
• COLD AIR
• COLD COOLANT
COLD START
-FAST
IDLE
• COLD AIR
• COLD COOLANT
COLD DRIVEAWAY
-PART THROTTLE
• WARM AIR
• WARM COOLANT
WARM DRIVEAWAY
-PART THROTTLE
• WARM AIR
• WARM COOLANT
HOT CRUISE
• WARM AIR
• WARM COOLANT
HOT
ACCELERATION
-60% THROTTLE
HOT ACCELERATION
-WIDE OPEN
THROTILE
SENSORS
APPROXI·
MATE TIME
CRANK ANGLE SENSOR AIRFLOW METER
(BASED ON
WATER
10-16°C,
or
I - - - - - - - - r - - - - l - - - - - - . - - - - - I
THERMO-
OXYGEN
50-60°F INTAKE AIR SENSOR
SENSOR
POTENTIO·
AMBIENT) G-SIGNAL NE·SIGNAL THERMO· METER
SENSOR
ZERO
ONE
MINUTE
SIGNAL
HAS NO
EFFECT
ON ECU
SIGNAL
HAS NO
EFFECT
ON ECU
LOW
VOLUME
AIRFLOW:
(3.0V)
COOL TO
WARM:
MEDIUM
VOLTAGE
(2.3Vand
SIGNAL
HAS NO
EFFECT
ON ECU
t
SENSOR
COLD:
TWO
MINUTES
I---~
1-1
DROPPING)
LOW TO
HIGH
VOLTAGE
(O-O.8V)
~
THREE
MINUTES
MORE
THAN
FOUR
SENDS
No.1
CYL-
INDER
TDC SIG-
NAL TO
ECU
SENDS
ENGINE
SPEED
SIGNAL
TO ECU
COOL TO
WARM:
MEDIUM
VOLTAGE
MODER-
ATE VOL-
UME
AIRFLOW'
LOW TO
MEDIUM
VOLTAGE
(1-3.5V)
(4.3-1.SV) MODER-
ATE TO
STRONG
VOLUME
AIRFLOW:
(O.5-1.5V)
WARM:
MEDIUM
VOLTAGE
(APPROX.
O.7V AND
DROPPING)
SENSOR
WARM:
HIGH
VOLTAGE
(ABOVE
0.6V)
SENSOR
HOT
SWITCH-
ING FROM
HIGH
VOLTAGE
(ABOVE
O.6V RICH)
TO LOW
VOLTAGE
(BELOW.
O.4V LEAN)
HOT: HIGH
LOW VOLTAGE
VOLTAGE (ABOVE
(APPROX. O.6V
1 - - - - - - - - - 1
MINUTES
I - - - I - - - l
0.4V) RICH)
DECELERATION
-CLOSED THROTTLE
HOT CURB IDLE
--EXTENDED
HOT ENGINE
SHUTDOWN
F-12
OFF OFF
OFF
LOW
VOLUME
AIRFLOW
(3.0V)
OFF
OFF
LOW VOLT-
AGE (BE-
LOW
O.4V
LEAN)
SWITCH-
ING FROM
HIGH TO
LOW
VOLTAGE
(0.4-0.6V)
SENSOR
HOT: LOW
VOLTAGE
(O.lV
LEAN) UN-
TIL SEN-
SOR
COOLS
DOWN
IGF
SIGNAL
SENDS
IGNITION
SPARK
SIGNAL
TO ECU
OFF
ATMOS·
PHERIC
PRESSURE
SENSOR
SENDS
VOLTAGE
SIGNAL
TO ECU
THAT
VARIES
WITH AL-
TITUDE;
VOLTAGE
(APPROX.
4V)
OFF