Cylinders 1 and 3 are next to one another. The misfires could arise from a head gasket failure between the cylinders.
Or both cylinders have suffered some valve/valve train issue.
Or it could be an injector problem.
Or low fuel pressure and 1 and 3 misfire first.
As much as I dislike messing with a car's fuel system in this case I think you are at least going to have to swap injectors moving the injectors from 1 and 3 to other cylinders and moving the injectors from those other cylinders to 1 and 3.
You don't have to do both at the same time. Try just swapping injectors between 1 and another cylinder. If the miss follows the injector then you can also proceed to cylinder 3. If the miss doesn't follow the #1 injector that is not a guarantee this will be the case for #3 injector. So you would or should try swapping #3 injector with an injector from an apparently healthy cylinder.
If the injector swapping doesn't help then that suggests the problem is internal to the engine. For a suspected head gasket failure or any issues with the valves a compression test is called for. And after maybe a leak down test.
Or both cylinders have suffered some valve/valve train issue.
Or it could be an injector problem.
Or low fuel pressure and 1 and 3 misfire first.
As much as I dislike messing with a car's fuel system in this case I think you are at least going to have to swap injectors moving the injectors from 1 and 3 to other cylinders and moving the injectors from those other cylinders to 1 and 3.
You don't have to do both at the same time. Try just swapping injectors between 1 and another cylinder. If the miss follows the injector then you can also proceed to cylinder 3. If the miss doesn't follow the #1 injector that is not a guarantee this will be the case for #3 injector. So you would or should try swapping #3 injector with an injector from an apparently healthy cylinder.
If the injector swapping doesn't help then that suggests the problem is internal to the engine. For a suspected head gasket failure or any issues with the valves a compression test is called for. And after maybe a leak down test.
