Hesitation, Sag, Stumble. Chevrolet Astro

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 2000 🢒 Astro - 2WD 🢒 Engine 🢒 Engine Controls - 4.3L 🢒 Hesitation, Sag, Stumble

Checks

Action

DEFINITION: The vehicle has a momentary lack of response when depressing the accelerator. The condition can occur at any vehicle speed. The condition is usually most severe when trying to make the vehicle move as from a stop sign. The condition may cause the engine to stall if it's severe enough.

Preliminary Check

Refer to Symptoms .

Fuel System Checks

•	Inspect the fuel pressure. Refer to Fuel System Diagnosis .

•	Inspect the throttle position (TP) sensor for binding or sticking. Voltage should increase at a steady rate as the throttle moves toward wide open throttle (WOT).

•	Inspect the manifold absolute pressure (MAP) sensor response and accuracy.

•	Inspect for water contamination in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Inspect the canister purge system for proper operation

•	Perform the Fuel Injector Coil Test. Refer to Fuel Injector Solenoid Coil Test .

•	Perform the Fuel Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 .

•	Inspect for low fuel pressure after a cold start or during a moderate or full throttle acceleration.

Ignition System Checks

•	Inspect for damaged spark plug wires.

•	Inspect for fouled spark plugs.

•	Inspect for proper ignition system performance. Refer to Enhanced Ignition System Diagnosis .

Additional Checks

•	Inspect the Service Bulletins for calibration updates.

•	Inspect the generator output voltage.

•	Inspect the exhaust gas recirculation (EGR) valve operation. Refer to Exhaust Gas Recirculation (EGR) System Diagnosis .

•	Inspect for a restricted exhaust. Refer to Restricted Exhaust in Engine Exhaust.