lsownerof2 Posted April 24, 2007 Share Posted April 24, 2007 Hey guys, this forum is great!!! bought 2 ls 400's in the last 3 months and this has been a life saver!!! I am having a rattle coming from under the engine when I am on the gas...any ideas what that might be? Any input would be helpfull. Thanks! Quote Link to comment Share on other sites More sharing options...
Vern Dias Posted April 24, 2007 Share Posted April 24, 2007 Are you are using premium grade gas.... If not, you need to be. Most likely, you are hearing detonation caused by too low an octane rating. Vern Quote Link to comment Share on other sites More sharing options...
larryp Posted April 24, 2007 Share Posted April 24, 2007 You didn't say what year the LS is - but i doubt it's gas. I've run nothing but regular in my 91 for 4 years and it never pings. Sounds more like something is loose in the engine compartment. Might try having some one rev it up while you look and listen. Quote Link to comment Share on other sites More sharing options...
nc211 Posted April 24, 2007 Share Posted April 24, 2007 this sounds like a heatshield on the upper converters have come loose. If it's a rattle, then just ping around underneath until you find something loose. My guess....heatshield has come loose... it happens. Quote Link to comment Share on other sites More sharing options...
lsownerof2 Posted April 24, 2007 Author Share Posted April 24, 2007 Sorry, its a 1993 with 162K on it. Quote Link to comment Share on other sites More sharing options...
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