1983 Jeep Cherokee Base, 4.2 C, AutomaticFACTORY OEM SERVICE PROCEDURE

Pulse Air Injection System: Operation

The pulse air system uses the alternating positive and negative pressure pulsations in the exhaust system to draw in fresh air through the air cleaner. Check valves are used to allow fresh air into the exhaust, but prevent exhaust from flowing back into the intake system.

Air is switched between upstream and downstream injection by 2 vacuum operated control valves. Each control valve is switched by an electrically operated vacuum solenoid.

The vacuum solenoids are switched on and off by the MCU according to engine operating conditions. A vacuum storage tank maintains the vacuum supply to the switching solenoids.

Factory Service Tools

Use the Manual With the Right Hardware

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

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When to See a Mechanic

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

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

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