rattling sound!
09-29-2004, 03:33 AM
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Originally Posted by Carvinta
You sure it's not an exhaust leak? Macs have been known to 'rattle'. 
10-01-2004, 01:21 AM
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Originally Posted by Carvin T/A
I put thicker oil in last oil change, and it had a noticeable effect. Do you hear it when cold only?
10-01-2004, 11:12 AM
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It quite possibly could be detonation. It might be knock retard as well, not sure how to diagnose those two actually, or not sure I would right away.
If you hear it in first gear though, then it's also possible the A/F tables were not setup correctly, which would have a slight adverse effect on performance. If you are not at WOT when you sweep the needle in first gear it's moving through it's PCM tables much faster than if you were to ease into the throttle at low RPMs. IIRC that would appear with Ls1edit, although not at the same rpm as WOT.
Anyway if you had it tuned recently might want to recommend to your tuner about getting some smoother table values in there for high RPM ranges. Just ask him that maybe he would know what to do without a lot of work. It could be the first two, or could be both or all three.
If you hear it in first gear though, then it's also possible the A/F tables were not setup correctly, which would have a slight adverse effect on performance. If you are not at WOT when you sweep the needle in first gear it's moving through it's PCM tables much faster than if you were to ease into the throttle at low RPMs. IIRC that would appear with Ls1edit, although not at the same rpm as WOT.
Anyway if you had it tuned recently might want to recommend to your tuner about getting some smoother table values in there for high RPM ranges. Just ask him that maybe he would know what to do without a lot of work. It could be the first two, or could be both or all three.
