how can you tell that your injectors are bad. what does the motor do or sound like I have an 89 4runner and my check engine light came on I tested it and it gave me two codes I don't remember the numbers but one code said it was running to rich and the other code said it was running to lean. I checked my spark plugs and the 1,3,5 side looked light grey, and the 2,4,6 side looked black. Is that my fuel injectors, cpu or what.