Section 08 ENGINE MANAGEMENT (4-TEC)
Subsection 02 (COMPONENT INSPECTION AND ADJUSTMENT)
Replacement
Unlock expansion tank and temporarily move
away to gain access.
Remove the fuel rail cover.
Disconnect CTS connector and remove CTS.
Install the new CTS and torque to 18 N•m
(159 lbf•in).
Reinstall remaining removed parts.
MANIFOLD AIR PRESSURE
SENSOR (MAPS)
IMPORTANT: Never mix up MAPS of naturally-as-
pirated and supercharged 4-TEC engines. Doing
so will automatically lead to a misfunction of the
ECM and will cause a bad engine calibration.
1
R1503motr173A
TYPICAL
1. Manifold air pressure sensor (MAPS)
NOTE: This sensor is a dual function device.
When engine is started and it runs at idle speed,
the sensor takes the atmospheric pressure and
stores it in the ECM. Thereafter, it takes the man-
ifold air pressure at operating RPMs.
Ensure sensor is correctly installed on intake man-
ifold. Otherwise, the MAPS could generate a fault
code for an unexpected sensor range at idle when
it reads the atmospheric pressure. Remove sen-
sor and check for oil or dirt on its end and if prob-
lem persists, check throttle plate condition/posi-
tion and the wiring harness. Perform the follow-
ing tests.
Voltage Test
Check the voltage output from ECM to the mani-
fold air pressure sensor ( MAPS).
Disconnect connector from MAPS and connect a
voltmeter to the terminals of the wiring harness
as per the following table.
CONNECTION VOLTAGE
Terminal 1 with engine
ground
5V
Terminal 2 with engine
ground
0V
Terminal 3 with engine
ground
0V
Remove and reinstall the safety lanyard to activate
the ECM.
If voltage test is good, replace the MAPS.
If voltage test is not good, check the continuity of
the MAPS circuit.
Resistance Test
Disconnect the ECM connector A on the ECM.
Using a multimeter, check continuity of circuits 12,
28 and 40.
If wiring harness is good, try a new ECM. Refer
to ECM REPLACEMENT procedures elsewhere in
this section.
Otherwise, repair the connectors or replace the
wiring harness between ECM connector and the
MAPS.
Replacement
Disconnect MAPS connector and remove the
MAPS.
Install the new MAPS paying attention to index
its tab into the adaptor notch. Apply Loctite 243
(blue) on screw then torque to 10 N•m(89lbf•in).
428 smr2004-Complete Line Up
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