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Tail pipe coloring

2K views 3 replies 3 participants last post by  JoeS 
#1 ·
Hey guys I am just asking this to get your ideas on if this is normal? I have a 2016 Z06 and it has about 700 miles on it and in looking at the tail pipes the two outside primary pipes are dark from the exhaust gasses, it looks like its just plain running to rich on its fuel mixture? Is this normal for a new vehicle? And will it get better as breakin of the engine continues?

Thanks much for your thoughts!
Karl
 
#2 ·
Due to gas having EPA mandated 10 to 15% ethanol which causes engines to run too lean and induce more engine knock GM had no choice but command non PE or WOT engine conditions from a normal
14.7:1 AFR to richer 14.1

Add hotter engine and air temps and even richer AFR commanded
Add higher elevations and even richer
All toll even less timing is commanded and loss of performance

1. if local buy non Ethanol gas
2. tune PCM to lean out for where you live, type of gas used and regain the performance loss.
3. if a choice stay away from the 15% ethanol, so ask gas stations what they use
 
#4 ·
Karl

It's normal - means you're driving it in a "Spirited Manner". Certainly you have noticed the louder exhaust tone in either "Sport" or "Track" modes. The performance exhaust system by-passes the muffler under high acceleration - thus dirty outer tips. Enjoy it!

Joe
 
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