Quote:
Originally Posted by XBarbarian
Thanks ZMan8.. just to clarify.. I understand what cold start refers too.. not temp, but engine state at start... I was asking specifically if any one knew where the shift in sound after 30 secs of cold start occurred.. like a valve closing or something.. with carb'd vehicle, the plate would close... with our cars..its something else..just a exhaust note change from an open throat ed sound, to muted after 30 secs..
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Look closely, the car opens throttle partially and revs higher for a little. On cold start I've seen 1400 rpm for 10 seconds before it drops to the 700 rpm idle slowly. The open throttle is what creates the exhaust note. Additionally the cold pipes probably amplify the noise slightly more than warmed up ones.