Rattle at 3/4 throttle to WOT
06-23-2006, 08:37 AM
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Rattle at 3/4 throttle to WOT I just noticed I get a nice metal rattle sound whenever I'm crusing at 3/4 to WOT. However, with the vehicle parked, I can wrap it all the way to 5K and it sounds smooth... so I don't think its an internal engine problem. I thought it was possibly loose suspension components, but nothing seems to clang/rattle when I shake the car by hand.
I did however drop my coil pack bolt somewhere down in the engine compartment when changing spark plugs, and the nut that holds the strut tower brace on (both have been replaced). Neither one made it to the shop floor, and neither could be found after about an hour of jacking the car up and searching every nook and cranny I could get my hands into.
Could the rattle possibly be those two stuck somewhere bouncing around? Any other things I should check for?
I did however drop my coil pack bolt somewhere down in the engine compartment when changing spark plugs, and the nut that holds the strut tower brace on (both have been replaced). Neither one made it to the shop floor, and neither could be found after about an hour of jacking the car up and searching every nook and cranny I could get my hands into.
Could the rattle possibly be those two stuck somewhere bouncing around? Any other things I should check for?
06-23-2006, 11:00 AM
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Sounds like spark knock to me. Check this thread https://ls1tech.com/forums/general-maintenance-repairs/530415-my-car-won-t-start-help-please.html
06-23-2006, 02:10 PM
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sounds like ill need to bust out the fuel pressure gauge, thanks for the advice! ill let ya know.... but just thinking, wouldnt it probably kick an SES light at WOT if it was knocking that bad?
Last edited by jhanson999; 06-23-2006 at 02:29 PM.
06-27-2006, 08:33 AM
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So I finally got around to hooking up the fuel pressure gauge. At idle, the pressure is fine and holds constant, even holds after shutting the car off so I don't think theres a leak anywhere. What seemed wierd to me, is that when you rev it up, pressure drops slightly (maybe 2-3 psi) for a split second then goes back to normal. Shouldn't the pressure increase as you rev it up?
06-27-2006, 09:28 PM
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Ok, had a GM tech check out the car with the scantool. Its definately spark knock, but the o2 sensors are showing that its not running too rich or too lean. He said it could be spark, or a bad tank of gas. I just replaced the spark plugs about a month ago, so I'm really hoping thats not the case. Any other ideas?
