Rough idle (irregularly firing or engine shaking)
| Cause | Correction | |
| Cold engine |
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Refer to Troubleshooting Logic for engine running too cold. |
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| Idle speed too low for the accessories |
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Check / adjust low idle screw. |
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| Engine mounts over-tightened, damaged or loose |
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Verify condition of mounts. |
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| High pressure fuel leak |
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Inspect / Correct leaks in the high pressure lines, fittings injection sealing washers or delivery valve seals. |
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| Air in the fuel system |
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Bleed the fuel system and correct the source of the air. |
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| Sticking needle valve in an injector |
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Replace the injector. |
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| Malfunctioning delivery valve |
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Replace delivery valves. |
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| Valves not sealing |
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Adjust valves. |
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| One or more cylinders losing compression |
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Perform a compression check and repair as required. |