1986 Mitsubishi Starion ESI-RFACTORY OEM SERVICE PROCEDURE

Idle Speed Control System

  1. Run engine at fast idle until coolant temperature is 185-205°F (85-90°C). Turn off engine. Disconnect accelerator cable from throttle lever of injection mixer. Loosen the 2 screws installing the throttle position sensor. Turn throttle position sensor fully clockwise. Tighten screws.
  2. Turn ignition switch to the "ON" position for more than 15 seconds, then turn ignition off. This will set ISC servo to specified position. Disconnect ISC servo harness connector. Start engine. Check engine speed and adjust to specification with screw. See Fig 1 .
    ENGINE IDLE SPEEDS

    Application ISC RPM
    Starion 750
  3. Stop engine. To read output voltage of TPS, insert test probe from rubber cap side of TPS connector and bring it into contact with connector pins. Insert test probes along "GW" lead (TPS output) and "B" lead (ground) of body side harness. See Fig 2 .
  4. Turn ignition switch to "ON" position without starting engine. Read TPS output voltage. Output voltage should be .45-.51 volts. If not, loosen TPS mounting screws and turn sensor until correct output voltage is obtained.
  5. Immediately open throttle valve, return it to original position and check for proper output voltage readjusting if necessary. Remove adapter, voltmeter and test probes and reconnect ISC servo harness connector.
  6. Make sure idle speed is normal. Stop engine and turn ignition switch from "OFF" position to "ON" position and after 15 seconds back to "OFF" position. Connect accelerator cable to throttle lever of injection mixer and adjust accelerator cable.
Fig 1: ISC Servo Idle Adjusting Screw
G42222
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.