Poor Driveability

FAULT INDICATIONS
Poor acceleration or shudder after engine braking. Symptom is permanent (not intermittent).

FAULT TRACING CONDITIONS
Before fault tracing, ensure that:
^ No diagnostic trouble codes are present,
^ The engine is at operating temperature, and
^ All fuses are clean and intact.

POOR ACCELERATION
^ Timing retarded due to knock (poor fuel, engine overheating, etc..).
^ Faulty secondary ignition components.
^ Blocked air cleaner or air intake.
^ Leaking pre-heat damper. (if so equipped)
^ Faulty variable intake system operation. (if so equipped)
^ Poor/uneven compression.
^ Low fuel pressure.
^ Blocked exhaust system.
^ Incorrect sensor signals.
^ Faulty Turbocharger. (if so equipped)
^ Wastegate valve open. (if so equipped)

SEVERE SHUDDER AFTER ENGINE BRAKING
^ Throttle body incorrectly adjusted.
^ Fuel Pump relay's two-stage function faulty. (if so equipped)

NOTE: Slight shudder during engine braking is normal. Adjust throttle body only if shudder is excessive compared with a known good vehicle.