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.
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HOMESERVICE MANUALSCHEVROLET1987SUBURBAN R20, 5.7 K, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCEADJUSTMENTTUNE-UP - V8ADJUSTMENTSTHROTTLE BODY INJECTION
1987 Chevrolet Suburban R20, 5.7 K, Standard
Throttle Body Injection
1987 Chevrolet Suburban R20, 5.7 K, StandardSECTION Throttle Body Injection
NOTE:
Adjustment is necessary only when throttle body assembly has been replaced.
- Remove air cleaner and gasket. Plug TBI unit vacuum port for THERMAC (Thermostatic Air Cleaner). With Idle Air Control (IAC) valve connected, ground terminal "A" to "B" at ALDL connector.
- Turn ignition switch to "ON" position, DO NOT start engine. Wait approximately 30 seconds for IAC valve pintle to extend and seat in throttle body.
- With ignition on, disconnect IAC valve electrical connector. Remove ground at ALDL connector. Using an awl, remove plug for minimum idle speed adjustment by piercing, then applying leverage.
- Start engine. Adjust idle screw to specification. Turn ignition switch "OFF". Reconnect IAC valve electrical connector. Install air cleaner and gasket.
SLOW IDLE SPEED (RPM)
| Application | Man. Trans. | Auto. Trans. | ||
|---|---|---|---|---|
| TBI | 600-650 | (1) 500-550 | ||
|
||||
NOTE:
Idle mixture is not adjustable on TBI models.
NOTE:
Idle speed is not adjustable on TBI models.
RENDER: 1.0x
NO RELATED
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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.