When I give the gas a little bit at part throttle, it sounds like a rattling or something coming from the driver side of the motor. At steady speed or full throttle I can't hear it. My SES light has been on 75% of the time the last month or so. I had it checked out at auto zone, it was the oxygen sensor and map sensor. First, I changed the map sensor and it was still throwing it. So, I took it back. I thought the noise was a bad O2 sensor, because of the code. So I changed it out, made no difference in the noise. But, I could tell a little bit better performance. I don't know if it's a loose rocker, knock or what. I checked the passanger side for a loose rocker, just haven't got around to doing the driver side yet. What do ya'll think it is???

 

Could it be the cat? or you have those?

 

I still have them but relocated them to the passanger side to make room for the cut-outs. I made sure that the exhaust wasn't hitting anything. the closest it gets is about 1/4"-3/8" from the engine bay.

 

Are you sure it's a rattle and not detonation? Other ideas include loose rocker, bad lifter, loose O2 sensor shield...

 

Would a loose rocker be hard to hear at cruising or WOT? When it quits raining I'm gonna double check the heat sheilds and all that.

 

I'd think so...it's possible that the sound of the engine gets louder than the rocker arm, if that's the problem. My engine has a bunch of valvetrain noise and various ticks that seem to get drowned out by the engine on the highway and under WOT.

If you have access to a scan tool or software, I'd check for knock retard first to see if you have an actual rattle or pinging.