Ford F150 Pickup. Instruction — part 1617

2003 ENGINE PERFORMANCE

Theory & Operation - CNG, Flex-Fuel & Gasoline

INTRODUCTION

This article covers basic description and operation of engine performance related systems and components.
Read this article before diagnosing vehicles or systems with which you are not completely familiar. To identify
vehicles and engines, see FORD MOTOR CO. - INTRODUCTION - CARS or FORD MOTOR CO. -
INTRODUCTION - TRUCKS article.

AIR INDUCTION SYSTEMS

SUPERCHARGER (F150 LIGHTNING 5.4L SC & MUSTANG 4.6L SC)

Supercharger Assembly

Supercharger assembly is a positive displacement pump designed to supply an excess volume of intake air to
engine by increasing air pressure and density in the intake manifold. Supercharger assembly incorporates a by-
pass system to reduce air handling losses when boost is not required, resulting in better fuel economy. See Fig.
1 . Supercharger can increase torque across entire engine operating range from 25-50 percent without
compromising driveability or emissions.

Supercharger is matched to engine by its displacement and belt ratio, and can provide excess airflow at any
engine speed. Drive gears for supercharger are pressed into place and are not serviceable. Supercharger must be
replaced as a unit. Supercharger contains 2 belt driven 3-lobed helical cut rotors which are supported by ball
bearings in front and needle bearings at the rear. The rotors helical shape and internal specialized porting
provide a smooth discharge flow and low noise levels during operation.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

Fig. 1: Exploded View Of Supercharger & Intercooler System
Courtesy of FORD MOTOR CO.

Supercharger By-Pass System

Supercharger By-Pass (SCB) system allows high pressure air at outlet of supercharger to vent back to inlet side
of supercharger. This equalizes pressure and eliminates boost for times when supercharger function is not
required. Descriptions of supercharger by-pass system components are as follows:

Vacuum By-Pass Actuator

During normal operation engine vacuum is applied to upper port of vacuum by-pass actuator. Lower port
of vacuum by-pass actuator references air pressure in clean air tube, cancelling out any pressure
difference in intake air system. Actuator opens during engine high vacuum conditions (by-passing

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

supercharger). As throttle is opened and engine vacuum decreases, vacuum by-pass actuator closes to
allow supercharger to pressurize air in intake manifold.

SCB Solenoid/Thermactor Air Control Solenoid

SCB solenoid is used to control intake manifold vacuum to vacuum by-pass actuator. The SCB solenoid
is de-energized during normal operating conditions. The Powertrain Control Module (PCM) will transmit
an output signal to activate SCB solenoid to apply stored vacuum from vacuum reservoir assembly to
vacuum by-pass actuator when an undesirable condition occurs in the engine. Once engine condition is
corrected, SCB solenoid will be deactivated by PCM allowing engine intake manifold vacuum to control
vacuum by-pass actuator.

Vacuum Reservoir Assembly

Vacuum reservoir assembly stores vacuum that is applied to the vacuum actuator when a condition such
as overheating or critical sensor failure is generated.

Supercharger Intercooler (Charge Air Cooler) System

Intercooler system is designed to cool induction air which has been heated by the supercharger. Removing heat
from pressurized air through an intercooler increases air density, which results in increased combustion
efficiency, engine horsepower and torque.

Intercooler system consists of the following components: an additional radiator and coolant reservoir
(independent from engine cooling system), an intercooler (charge air cooler) located in lower intake manifold
and a charge air cooler pump (electric water pump) located at right front side of engine compartment and
intercooler coolant hoses. See Fig. 2 .

Charge air cooler pump is controlled by PCM and charge air cooler pump relay to maintain a desirable intake
air temperature signalled by a second intake air temperature sensor (IAT2) located in lower intake manifold.

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline

Fig. 2: Location Of Intercooler System Hoses (F150 Lightning 5.4L SC)
Courtesy of FORD MOTOR CO.

VARIABLE INDUCTION SYSTEM

Intake Manifold Runner Control - Focus 2.0L (VIN P), Econoline & Pickup 4.2L (VIN 2) & Windstar 3.8L (VIN 4)

On 3.8L & 4.2L engines, Intake Manifold Runner Control (IMRC) system consists of a remote mounted electric
actuator with an attaching cable or linkage to operate the housing butterfly valve plate levers located between
intake manifold and cylinder head(s). See Fig. 3 -Fig. 6 . On 2.0L, IMRC uses a motorized actuator mounted
directly to a single housing, between intake manifold and cylinder head, without use of a cable or linkage. PCM
uses a positive change in Throttle Position (TP) sensor along with the increase in engine RPM from Crankshaft
Position (CKP) sensor to open butterfly valve plates.

IMRC housing is an aluminum casting with 2 intake air passages for each cylinder. One passage is always open

2003 Ford Pickup F150

2003 ENGINE PERFORMANCE Theory & Operation - CNG, Flex-Fuel & Gasoline