i took the plug out and had the coil plugged in and spark plug in the coil and the plug was firing but it didnt look like it was firing hard enough to me , the plug was black like it was dirty and wasent firing and i just changed them and swaped the coils around, can i check the injecter with with a volt meter ? or any ides what it could be ? my check engine light is on showin the knock sensor but i think thats from the missfire and the code for the gas cap not being on but i bought a new cap and cleared the codes and drove it and it still skipped around 35-40 and still shows all 3 codes thanks in advance
