ok so im haveing some issues with my check engine light which means im having some issues with the car. First im getting a P0300 which is a random/multiple cylinder misfire i just got my car tuned through Jestr Tuning and i tried the whole regap of the spark plugs i went to .022, .024, .025, .026 none of which worked still got the light everytime. Im thinking it my be a injector. Second im getting a
P0420 wich is Catalyst effciency below threshold (bank1) im not sure what to think of this i went to see if maybe it was a exaust leak but i dont have one, so im stumped if anyone can help please give me you susgestions im up for anything

Thanks
Robert

 

A good number of people have the P0300 misfire code. I would see if you can log or have someone run some logs for you to see if you are knocking or if there is anywhere in your tune that things need to be corrected. As far as the P0420 that just means your rear O2 sensor is reading that your cat is burnt out. This often comes from running a test pipe or even a high flow cat with no CEL fix for the rear O2 sensor (simulator, spark plug defouler, etc.) Hope that helps.

 

it's a pesky issue - very frustrating. The dealer finally replaced all of my injectors this week and my issue has temporarily went away (4days now from every day). My issue was mostly happening at idle but sometimes around 3k rpms.

Also you might read this thread. My car was doing this on the stock tune as well as a dynoflash tune and a jestr tune. It's likely a problem with the car and not the tune.

https://www.evolutionm.net/forums/sh...=196243&page=5

 

run your tank empty and try a different gas station/brand, especially if your usual is on the beach