Cylinder Misfire

[melrose3]

Hello!



I had taken my car to a Kia dealership for an evap canister recall and to check on the fuel pump for an additional letter I received in the mail from Kia re: low-pressure fuel pump leak extended warranty. They checked the fuel pump port and said it didn't show any signs of leaking. When I picked my car up, I noticed a small misfire on my drive home. I didn't think much of it because I'm not too familiar with cars but the next day, while it was continuing to misfire, the CEL came on. I called the dealership and made an appt for a week out because they couldn't get me in sooner.



Fast forward a week, and my car was still misfiring but literally on my way to my appointment at the dealership, the CEL went off. I called them and told them I was going to reschedule (I was really worried about it not actually being from something they did and then have them charge me).



Now, the car continues to misfire even though the CEL is off and when I read the CEL code, it said it was P0303- Cylinder 3 Misfire. I should also add that the gas milage has gone down significantly.



Could this be because of something they did with the fuel pump? I'm assuming it is just because it started immediately after I picked my car up from them, but I just want to make sure I'm not going in there blind and having them try to charge me.

[shorod]

Usually work on the fuel pump would not be likely to impact only a single cylinder. A possible exception to this would be if in the process of troubleshooting the fuel pump they managed to dislodge some debris that happened land in the fuel injector for cylinder #3 only. That's possible, and I'm not sure if your Kia has an external fuel filter that should trap any debris between where they were working and the fuel rail.

Keep in mind too that a misfire on a cylinder can be caused by many things that are not directly fuel-related. Based on what you've written above though, it's reasonable for you to suspect that diagnosing the P0303 may cost you out of pocket as the timing could be completely coincidental with the work you had it to the dealership for. With that in mind, you could also have an independent shop that you trust take a look at the P0303 code. If it ends up being completely unrelated, the independent shop's labor rate will likely be quite a bit less than the dealerships. And if the shop determines that the issue stems from work the dealership did, you should work with the dealer to make sure the independent shop gets paid by them to diagnose the problem.

-Rod