Diagnosing Fuel Quality Problems
Symptoms
A fuel-quality problem may be indicated by the following driveability symptoms:
- Spark knock/detonation
- Hard cold start and garage stalls
- Poor cold performance
- Tip-in hesitation, sag, or stumble (momentary lack of response during initial acceleration)
- Surges and/or chuggles
- Lack of power, sluggish, or spongy
- Cut out or misses
- Rough/unstable idle (intake or exhaust valve deposits)