I took my Eoes to the dealer for a CEL and was told it was something in the secondary air system, pus I had mis-fire codes P0300,P0301,p0302, P0303, P0304. For the mis-fire codes they wanted to do some sort of chemical wash. I was skeptical if this was a real issue that would do any good. The car is running fine so bought a bottle VW/Audi fuel additive (#G 001780M3), put it in and ran on the highway at 5K RPM. After about 3 miles the EPC light went on and the engine sounded like a cylinder was not firing. I got off the highway, turned the car off and went to look under the hood. Nothing seemed to be out of place. I started it back up and no EPC light and the car ran better, but not as good as before. I was assuming a fuel injector had stuck open and fouled a plug. This has happened to me twice before and two injectors have been replaced under a VW extended warranty. I just replaced the plugs and coils last week and yesterday I pulled the plugs and it appears the wrong plugs are in the car. When I did a google search for the number on the plugs it appears to be a colder plug. I assume a colder plug will foul out easier, especially at the higher RPM I was doing, than the normal plug. I haven't totally rules out an injector issue but had a question.
If the dealer does a scan, will the EPC fault code appear? If so, if I remember correctly from past experience it will not distinguish what exactly is wrong with the cylinder. I believe the two times this has happened before the dealer had to switch around the coils and plugs to rule issues with those out, before replacing the injectors. I am within 600 miles of the end of the extended warranty on the injectors and do not want to take any chances with missing something.
If the dealer does a scan, will the EPC fault code appear? If so, if I remember correctly from past experience it will not distinguish what exactly is wrong with the cylinder. I believe the two times this has happened before the dealer had to switch around the coils and plugs to rule issues with those out, before replacing the injectors. I am within 600 miles of the end of the extended warranty on the injectors and do not want to take any chances with missing something.