Hesitation, Sag, Stumble. Chevrolet Chevrolet C-Series Medium Duty Truck B7 1998

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1998 🢒 Chevrolet C-Series Medium Duty Truck B7 🢒 Engine 🢒 Engine Controls - 6.0L and 7.0L 🢒 Hesitation, Sag, Stumble

Hesitation, Sag, Stumble

Checks

Action

DEFINITION: The vehicle has a momentary lack of response when pushing down on 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 for the Important Preliminary Checks.

Fuel System Checks

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

•	Check the TP sensor for binding or sticking. Voltage should increase at a steady rate as the throttle moves towards Wide Open Throttle (WOT).

•	Check the MAP sensor response and accuracy. Refer to the Manifold Absolute Pressure Sensor Output Check Diagnosis .

•	Check for water contamination in the fuel.

•	Check the EVAP Canister Purge system for proper operation. Refer to Evaporative Emission Control System Diagnosis .

Ignition System Checks

•	Check for faulty spark plug wires.

•	Check for fouled spark plugs.

•	Check for an open IC reference low circuit, or ignition timing. Refer to Distributor Ignition (DI) System Diagnosis .

Additional Checks

•	Check the Service Bulletins for PROM updates.

•	Check the generator output voltage.

•	Check the EGR valve operation. Refer to Exhaust Gas Recirculation (EGR) System Diagnosis .