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Running rich signs?

steventure

NAXJA Forum User
Location
Indiana
I stopped by a muffler shop today to have them help me bend my tailpipe over a bit because it was riding my shackle. He pointed at my new muffler and said oh you’re running rich. It now has a golden color with a blueish rainbow effect going on. Roughly 2 weeks old. Got me thinking if I was actually, or if he was just trying to get me in for “service”
I have no CEL. Idles around 700. Runs good no power loss. Replaced both my o2 sensors with NTK ones about a year ago. New muffler and CAT. Spark plugs look normal. Fuel pump pressure is a little below 50 at idle, sits at 30 with key in ignition. Sits there for awhile with the engine off but it will eventually drop, is this normal? Called walker they said the coloring is normal for their SS mufflers.
I really don’t know what mpg I’m getting I never really cared.
Is the only way to check fuel to air ratio with a dyno test?

I’m probably getting myself worked up over nothing but with gas prices these days I can’t help myself from wondering, lol.
 
OBD-II then. If it is running rich, the Check Engine Light would very likely be ON.

A decent OBD-II trouble reader or cell phone app will have live data to monitor the engine performance in real time. I would not trust a muffler guy to diagnose drive-ability issues.

https://www.naxja.org/forum/showthread.php?t=1165122
 
What you are describing sounds like typical discoloration on stainless metal due to heat. You can always pull your spark plugs and check them. They tell you the truth about what is happening in each cylinder.

If it were true what the muffler man said, then the amount of fuel to somehow discolor metal in a muffler would have to be significant. IMHO.
 
What you are describing sounds like typical discoloration on stainless metal due to heat. You can always pull your spark plugs and check them. They tell you the truth about what is happening in each cylinder.

If it were true what the muffler man said, then the amount of fuel to somehow discolor metal in a muffler would have to be significant. IMHO.

Running that rich, your CAT would be overheating first, not the muffler.
 
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