OK guys - I know I have read about this before. I did a search and learned a little bit. Anyway - 2002 LS1 - only 18K miles (pampered I might add) - the engine knocks when it is cold. As soon as it warms up it goes away. It is quite noticable outside - a buddy even asked me about it. I baby it 'til it gets up to normal operating temp. How concerned should I be? I am about to take it in for a couple of warranty items - is bringing it to their attn enough? It has had Mobil 1 every 3-5K miles since new.
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Silver 02 WS-6, 6 speed, Corsa cat-back, SLP lid, K&N filter, BMR STB, !CAGs, Lou's short stick, MSD wires, MTI "Hammer" cam, ASP underdrive pulley, Hooker LTs, Hooker ORY, Comp 918s, TR pushrods, UMI Sfcs, UMI LCAs, NGK TR55s, Hotchkis springs
Dyno'd 4/24: 330.9 RWHP/ 344.8 RWTQ (Before cam, headers, and pulley)
Dyno'd 5/1: 383.5 RWHP / 380.5 RWTQ (393 actual RWHP) -
My 95 LT1 does it too. Sounds like a diesel when I let off the gas and it's cold. I wondered if the knock sensor was bad. I run 93 octane gas too.2002 Electron Blue Vette, 1SC, FE3/Z51, G92 3.15 gears, 308.9 RWHP 321.7 RWTQ (before any mods), SLP headers, Z06 exhaust, MSD Ignition Wires, AC Delco Iridium Spark Plugs, 160 t-stat, lots of ECM tuning
1995 Z28, many mods, SOLD
A proud member of the "F-Body Dirty Dozen" -
I expect that most on the board will say the knock when cold is pretty normal. If it continues after warm up, might check it out. Also, don't puch it when cold--let it warm up sufficiently.2000 Z-28 Convertible, neutral leather interior and neutral top, hotchkis STB, SLP Bowtie Grill, WhisperLid, K&N, cold air inductionComment
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Thanks guys - I had read a lot about it and have experienced it before - but all on LT1s. Was not sure if it was common on LS1 as well.Silver 02 WS-6, 6 speed, Corsa cat-back, SLP lid, K&N filter, BMR STB, !CAGs, Lou's short stick, MSD wires, MTI "Hammer" cam, ASP underdrive pulley, Hooker LTs, Hooker ORY, Comp 918s, TR pushrods, UMI Sfcs, UMI LCAs, NGK TR55s, Hotchkis springs
Dyno'd 4/24: 330.9 RWHP/ 344.8 RWTQ (Before cam, headers, and pulley)
Dyno'd 5/1: 383.5 RWHP / 380.5 RWTQ (393 actual RWHP)Comment
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The piston slap is extremely common on the LS1s. Mine was one of the looser ones. Heard it from day one (if you know what to listen for). By 12,000 miles was very pronounced when cold and could tell it was there when warm. Now, at 75k miles, it's my old buddy.... wouldn't know what to without it......
Anyway ... it's pretty much a "deal with it" situation. If the dealer doesn't try to tell you it's injectors or something stupid, .... I still wouldn't feel comfortable having the dealer yank the engine and open it up.
I really would recommend just living with it. Look at it this way..... you're making extra HP since you have less piston to cylinder friction.........
Gordon
PPC
www.provenperformanceconcepts.com
Gordon Arnold - '00 WS6 T/A - SoldComment
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