All 4-Cyl. Engines, Except 4XE1 Impulse
- Firmly set the parking brake and block the drive wheels.
- Place the transmission in N .
- Set the engine tachometer.
- Make sure the throttle valve is fully closed.
- If equipped with air conditioning, make sure it is turned OFF .
- Place the manual transmission in N or the automatic transmission in P .
- Disconnect the electrical connector from the Vacuum Switching Valve (VSV) on the pressure regulator; the idle speed should be 850 and 19950 rpm.
- If the idle speed is not correct, turn the adjusting screw A on the throttle body.
- The idle speed is controlled by the ECM and Idle Air Control (IAC) valve. No adjustment is necessary or possible.
- This system is used on the 1983 and 1988 EFI Impulse with automatic transmission.
- Push the accelerator pedal fully to the floor. Allow the engine speed to increase and then release the pedal.
- Check to make sure the engine speed returns to 1,00 and 192,100 rpm and them continues to slowly drop towards the correct idling speed.
- If not, set the engine speed to 2,000 rpm with the throttle lever.
- Tighten the adjusting screw until it just makes contact with the dash pot shaft head.
- Lock the adjusting screw in position with the locknut.
- Repeat the dash pot touch rotation speed check procedure as described above.
No idle mixture adjustment is necessary or possible.