Q: Misfire cylinders 4 and 7.

asked by on July 10, 2016

My truck has been misfiring on cylinders 4 and 7. I've changed the plugs and coils fuel injectors are clicking and I've ran a compression test both cylinders were around 165-170. At first it was throwing a lean code on bank one as well now is throwing a rich code. Cylinder 4 and the rich code seem to be intermittent because they go from stored codes to pending codes. The lean code was the same as well. I've checked for spark checked for vacuum leaks and checked for any fuel leaks. I changed the fuel filter and my fuel pressure was good as well.

My car has 145000 miles.
My car has an automatic transmission.

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You need to check the PCV tube that goes behind the intake and connects into the back side. The hose can get a leak in it, causing a vacuum leak on the back side. This will create lean conditions that may be worse for cylinders 4 and 7 specifically on this engine.

If the hose is good then try and have the injectors replaced or cleaned for these two cylinders. You could swap them with different cylinders to see if the problem moves along to the other cylinder, doing so will help pinpoint the issue.

If you decide to get the car looked at, consider YourMechanic, as a certified technician can come to your location and diagnose your car’s misfire. An accurate repair can then be made once the problem has been pinpointed.

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