Quote:
Originally Posted by JFM-jr
NPP fuse is pulled and on a cold start after about 30 seconds the volume of the exhaust note changes VERY noticeably. Id have a hard time believing its simply coming off high idle. It sure sounds like something mechanical happens to me.
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There is more to it during cold start. One of the reasons the exhaust is louder is that during a cold start the timing is retarded to meet emissions standards, etc.
When it is colder out you may notice it to be even louder as more timing is pulled during a cold start. Once the engine temp starts to rise you notice it start to come off high idle and the ECU adds more timing, which affects the exhaust note.