I've posted on this problem before, but since forum can't be searched....

I had the dreaded engine rattle at 2500-2800 RPM under light loads, like up a slight hill and light-medium throttle or on cruise control. (97 SE, 63K miles, auto).

After trying other things, reading the service manual, and beating my head against the wall, I finally put some good fuel system/injection cleaner in my tank ( glove box manual say's not to).
Problem went away. I've put on 1500 miles since, and the rattle has never returned. It was not a ping. And more than a knock. It sounded more like metal rattling at about same RPM of engine. Noise was not present when not under a load, or full throttle.

Must have been running too lean under certain conditions due to a plugged injector, maybe EGR, or something else related to a dirty fuel delivery system. Anway, you the in-fuel tank cleaner or having injectors professionally cleaned before going to a dealer to get ripped.
Some have had their timing chain replaced only to have the same noise be there $1200 later. (Or coil packs, plugs, EGR, knock sensor).

 

Sounds good to hear, I been noticing a weird rattle also for the past year or so. I always thought it was somethign loose under the hood that vibrated but Ill give the cleaner a chance since I cant figure exactly what this noise is.

BTW what brand cleaner did you use? I used that chevron techron stuff in the blue bottle like 6 months ago but obviously the noise is still here

 

yeah i'd also like to know...
i would like to clean the injectors before i encounter any problems

 

BG 44K and Amsoil PI are quite recommended.

 

I used, and only because I had it in laying around my garage for my truck, Slick-50 Fuel system cleaner. No, it does not have PTFE in it. It is made by Quaker State Oil co. Ask a good mechanic what he recommends. Sometimes an auto parts store will have a guy that knows his stuff too. The cheap stuff ($1-5 bottle) probably won't work.

let me know if the cleaning helps.