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Q: Repeated Fuel Injector Seal Failure

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I've got a p0302 code, misfire on cylinder 2. Changed the spark plugs, wires, and coil pack to no avail. Pulled the number 2 injector and swapped it with one I pulled at a salvage yard. Problem was fixed for about 50 miles, car ran great, no misfire. Then code came up again with a rough idle and gas smell. Pulled the injector and the upper o ring had ripped. Repeated this 4 times. I'm using OEM o rings from injectors I'm getting at the yard, but they keep failing. I really want to know the underlying cause for all these failed o rings before I swap any more. Any ideas?

My car has 190000 miles.
My car has a manual transmission.

O-rings on fuel injectors have to be liberally lubricated with engine oil prior to installation. Installation is typically made with a twisting motion as you push the injector into the bore on the fuel rail. Be sure the aluminum surface (bore) in the fuel rail appears polished and perfectly smooth with no nicks. If you install with engine oil and use a twisting downward motion you should have no problem. If you want to have this checked, or would like to have an expert install new injector o-rings for you, a certified pro from YourMechanic can come to your home or office to perform this.

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