On my 94 80 Series Landcruiser I have a noise. I thought it was pinging. Switched to hi-test fuel. No difference. Could be a rattle. Thought maybe a heat shield. Can't find a loose one. Makes the noise under load. Not evident with slow acceleration on the flat. Omnipresent under heavy acceleration or uphill. Any good ideas on how to chase it down? My check engine light comes on frequently but everytime I've checked it, it's the EGR code which is a frequent occurrence on the 94's.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13