Pontiac Fiero 1988 Service Manual page 628

DRIVEABILITY AND EMISSIONS - FUEL INJECTION (PORT) 6E3-A-45
CODE 33
I V I M N I F O L D
ABSOLUTE PRESSURE
(MAP) SENSOR CIRCUIT
(SIGNAL VOLTAGE HIGH - LOW VACUUM)
2 . 8 L " P " S E R I E S ( P O R T )
©
• IF ENGINE IDLE IS R O U G H , UNSTABLE OR INCORRECT,
CORRECT BEFORE USING CHART. SEE SYMPTOMS IN
SECTION " B " .
9
ENGINE IDLING.
• DOES " S C A N " DISPLAY A MAP OF 4.0 VOLTS OR O V E R ?
YES
NO
©
* IGNITION " O F F " .
• DISCONNECT MAP SENSOR ELECTRICAL CONNECTOR.
* IGNITION " O N " .
• " S C A N " SHOULD READ A VOLTAGE OF 1 VOLT OR L E S S .
DOES IT?
YES
CODE 33 IS INTERMITTENT.
IF NO ADDITIONAL CODES WERE
STORED, REFER TO "DIAGNOSTIC
AIDS" ON FACING PAGE.
NO
• PROBE CKT 469 WITH A TEST LIGHT TO 12 VOLTS.
• TEST LIGHT SHOULD LIGHT.
DOES IT?
CKT 432 SHORTED TO V O L T A G E ,
SHORTED TO CKT 416, OR
FAULTY ECM.
YES
NO
PLUGGED OR LEAKING
SENSOR VACUUM HOSE OR
FAULTY MAP S E N S O R .
OPEN CKT 469.
IGNITION "ON" ENGINE STOPPED VOLTAGES
ALTITUDE
VOLTAGE RANGE
Meters Feet
Below 305 Below 1,000 3.8—5.5V
305—610 1,000-2,000 3.6—5.3V
610—914 2,000-3,000 3.5—5.1V
914--1219 3,000-4,000 3.3—5.0V
1219-1524 4,000-5,000 3.2—4.8V
1524-1829
5,000-6,000 3.0—4.6 V
1829-2133
6,000-7,000 2.9—4.5V
2133-2438
7,000-8,000 2.8—4.3V
2438-2743
8,000-9,000 2.6—4.2V
2743-3048 9,000-10,000 2.5—4.0V
LOW ALTITUDE = HIGH PRESSURE = HIGH VOLTAGE
6-17-87
7 S 3 2 1 0 - 6 E