Starion L4-2555cc 2.6L SOHC Turbo VIN N FI (1985)
Throttle Position Sensor: Technical Service Bulletins
Engine - ISC/TPS Adjustment (ECI Models)
SUBJECT:
ISC/TPS ADJUSTMENT (ECI MODELS)
NO.
STB 85-14-002
DATE
February, 1985
MODEL
All with ECI
This bulletin supercedes STB-83-14-009, STB-84-14-005 and STB-84-14-008. Please remove these bulletins from your binders and discard them.
DESCRIPTION The Idle Speed Control (ISC) servo motor performs the functions of opening the throttle during cranking, fast idle speed control, A/C
idle-up control and throttle modulation on deceleration. The ISC servo motor adjusts throttle position very precisely by means of a motor-driven screw
acting upon a lever on the throttle shaft.
Also connected to the throttle shaft is the Throttle Position Sensor (TPS), which senses the throttle position and sends an appropriate voltage signal to the
ECI computer.
FIGURE 1 - ISC/TPS - TYPICAL ECI INSTALLATION
Since both the ISC and TPS are connected to the same shaft (See Figure 1), a change in the adjustment of one affects the adjustment of the other.
Therefore, whenever the ISC servo motor is adjusted or removed and installed, the TPS must always be checked and adjusted. Also, since the voltage
output of the TPS affects the engine performance and emissions, it is important that it be adjusted properly.
PROCEDURE
1.
With the engine at operating temperature, all lights and accessories OFF and the transmission in NEUTRAL, or PARK disconnect the accelerator
cable from the throttle lever at the injection mixer.
2.
Turn the ignition switch ON (do not start engine), leave it ON for a full 15 seconds, and then turn it OFF. NOTE:
This sets the ISC servo motor to the specified position.
