Engine - ISC/TPS Adjustment (ECI Models)
85mitsubishi02SUBJECT:
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.
FIGURE 2:
3. With the ignition switch OFF, disconnect the ISC connector (see Figure 2) and then start the engine.
FIGURE 3:
4. After the engine has idled for 30 seconds, adjust the idle speed to specifications in table 1 using the Idle Speed Adjusting screw shown in Figure 3.
5. Turn off the ignition.
FIGURE 4:
TABLE I: BASE IDLE RPM SPECIFICATIONS FOR ISC/TPS SETTING
Cordia/Tredia/Mirage Turbo 600*
Galant 650
Starion 750
* 500 if less than 300 miles
6. Insert the negative (-) probe of a digital voltmeter into the green/black wire of the TPS connector and the positive(+) probe into the green/white wire. See Figure 4. NOTE:
^ Do not disconnect the connector.
^ For convenience you may connect the negative probe of the voltmeter to any suitable ground instead of the ground in the connector.
7. Turn the ignition switch ON (do not start the engine) and read TPS output voltage.
FIGURE 5:
8. If the TPS output voltage reading is outside the specification in Table II, adjust the TPS by loosening the retaining screws and rotating the TPS as shown in Fig. 5 until the specified voltmeter reading in Table II is obtained. Tighten the screws.
TABLE II: TPS OUTPUT VOLTAGE SPECIFICATIONS
Model Voltage
All 0.47 +/- .02
9. Fully open the throttle once, then return it to its original position and check again for output voltage. Readjust if necessary.
10. Remove the voltmeter.
11. Make sure curb idle is at specification:
Cordia/Tredia/Mirage 700 +/- 100 rpm
Galant 750 +/- 100 rpm
Starion 850 +/- 100 rpm