I have this rattle diesellike sound on low revs and only when applying throttle. The rattle stops immediately as I release throttle or if I keep the revs steady on one spot. It is only there when rpm are rising. When the sound stops, its not calming down and then disapears, its more like on off mode. And is there from idle to 2500 rpm, maybe more but I cant hear it later.. You can hear it at best from idle to 1300rpm. It is a rare 75 turbo but engine internals are same or similar to all alfa nord engines. The sound is there also if I disconnect spark plugs cables one by one. No difference. Also I have checked valve train and remove the cams and lifters and all looks fine there. Valve lash is on specs. Oil pressure is fine. The things gets little better when engine is hot. What could be in these engines that cause that kind of rattle that goes away like on-off as soon I release throttle?