I just bought a 2003 Chevy Silverado 1500 z71 4x4, 135,000 miles, 4.8L V8 with some rust, it does have a slight ruff idle and sounds like lifter knock when hot or cold, if i blip the throttle the knock go's away for a few mins, i changed the oil and spark plugs as soon as i got it home, the check engine light was on as well. i went to advanced auto and had them scan the code, it came up as knock sensor bank 2, i purchase 2 new knock sensors, wiring harness and intake gasket, installed everything and the code came back after a few days of driving it as bank 1 now, i traced the wires from the knock sensor harness and everything looks fine, i pulled them back out and replace them once again. but same thing, engine light came back after a few days. would replacing injectors or coil packs help me any?
My car has 135000 miles.
My car has an automatic transmission.
The sensors are doing their job and telling you there is a knock in the engine. Even though it may seem like the sound went away, you may not be able to hear it when you drive but the sensors can. The knock sensors are designed to produce a voltage when they hear a knock noise from the engine internal parts.
You need to have the noise you hear checked by a mechanic to see what is the cause and what needs to be done in order to fix it.