Engine Symptom Troubleshooting
- Verify malfunction symptoms using the following diagnostic index, then go to the appropriate troubleshooting chart.
Diagnostic Index
DIAGNOSTIC INDEX
| No. | TROUBLESHOOTING ITEM | DESCRIPTION | |
|---|---|---|---|
| 1 | Melting of main or other fuses | - | |
| 2 | MIL illuminates | MIL is illuminated. | |
| 3 | Will not crank | Starter does not work. | |
| 4 | Hard to start/long crank/erratic start/erratic crank | Starter cranks engine at normal speed but engine requires excessive cranking time before starting. | |
| 5 | Engine stalls. | After start/at idle | Engine stops unexpectedly at idle or after start or both. |
| 6 | Cranks normally but will not start | Starter cranks engine at normal speed but engine will not run. | |
| 7 | Slow return to idle | Engine takes more time than normal to return to idle speed. | |
| 8 | Engine runs rough/rolling idle | Engine speed fluctuates between specified idle speed and lower speed and engine shakes excessively. | |
| 9 | Fast idle/runs on | Engine speed continues at fast idle after warm-up. Engine runs after ignition switch is turned off. | |
| 10 | Low idle/stalls during deceleration | Engine stops unexpectedly at beginning of deceleration or recovery from deceleration. | |
| 11 | Engine stalls/quits. | Acceleration/cruise | Engine stops unexpectedly at beginning of acceleration or during acceleration. Engine stops unexpectedly while cruising. |
| Engine runs rough. | Acceleration/cruise | Engine speed fluctuates during acceleration or cruising. | |
| Misses | Acceleration/cruise | Engine misses during acceleration or cruising. | |
| Buck/jerk | Acceleration/cruise/deceleration | Vehicle bucks/jerks during acceleration, cruising, or deceleration. | |
| Hesitation/stumble | Acceleration | Momentary pause at beginning of acceleration or during acceleration | |
| Surges | Acceleration/cruise | Momentary minor irregularity in engine output | |
| 12 | Lack/loss of power | Acceleration/cruise | Performance is poor under load. (e.g., power down when climbing hills) |
| 13 | Knocking/pinging | Acceleration/cruise | Sound is produced when air/fuel mixture is ignited by something other than spark plug, (e.g., hot spot in combustion chamber) |
| 14 | Poor fuel economy | Fuel economy is unsatisfactory. | |
| 15 | Emission compliance | Fails emissions test. | |
| 16 | High oil consumption/leakage | Oil consumption is excessive. | |
| 17 | Cooling system concerns | Overheating | Engine runs at higher than normal temperature/overheats. |
| 18 | Cooling system concerns | Runs cold | Engine does not reach normal operating temperature. |
| 19 | Exhaust smoke | Blue, black, or white smoke from exhaust system | |
| 20 | Fuel odor (in engine compartment) | Gasoline fuel smell or visible leakage | |
| 21 | Engine noise | Engine noise from under hood | |
| 22 | Vibration concerns (engine) | Vibration from under hood or driveline | |
| 23 | A/C does not work sufficiently. | A/C compressor magnetic clutch does not engage when A/C is turned on. | |
| 24 | A/C is always on or A/C compressor runs continuously. | A/C compressor magnetic clutch does not disengage. | |
| 25 | A/C is not cut off under WOT conditions. | A/C compressor magnetic clutch does not disengage under WOT. | |
| 26 | Exhaust sulphur smell | Rotten egg smell (sulphur) from exhaust | |
| 27 | Fuel refill concerns | Fuel tank does not fill smoothly. | |
| 28 | Fuel filling shut off issues | Fuel does not shut off properly. | |
| 29 | Constant voltage | Incorrect constant voltage | |
| 30 | Spark plug condition | Incorrect spark plug condition | |