Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Altitude Control System
The altitude control system consists of a diaphragm spring installed horizontally in the housing. On the bottom of the housing is a reference pressure, which replaces atmospheric pressure and is modulated by a barometer box. The difference between charge pressure and reference pressure determines the position of the diaphragm spring.
The diaphragm spring lifts with decreasing air pressure. The spring-loaded adjusting rod moves vertically against the spring force, and the guide pin moves horizontally because of the control taper. This causes the stop lever to swing around its pivot point, and forces the tensioning lever in the direction of the full load stop screw, against the governor spring force.
This moves the control valve in the "stop" direction and reduces the fuel delivery rate to conform with the airflow rate. The altitude switch closes above a preset altitude. When the switch closes, a signal is sent to the electronic control assembly. The electronic control assembly processes this signal and charges injection timing to improve efficiency.
Use the Manual With the Right Hardware
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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.
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