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Q: Missfiring engine

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The ECM is not functioning properly, the cylinders 4,5 and 6 have been malfunctioning.

Check on the misfiring, constant flow from EUI 4,5,6. Test EUI and was noted to be ok, swap EUI from 2,3 and no change was noted.

A: Hello. Knowing the you have a good fuel sup...

Hello. Knowing the you have a good fuel supply to the engine is a great start. Have you looked into you spark plugs and ignition system? Start by testing for a good spark at all plugs. This will test the coil and the wires. If needed, replace all plugs and wires at the same time (rather than one or two of them). This keeps wear on the engine consistent, and can make future repairs easier to diagnose. Catalytic converters and oxygen sensors can also play a large role in the engine performance. These can be tested with a good scan tool, or with a multimeter. The ECM may be trying to compensate for another issue with the vehicle. The only way to tell is to do some further testing.

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