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- 4.6L (1996-2004 Modular) Mustang (https://mustangforums.com/forum/4-6l-1996-2004-modular-mustang-7/)

- - Plugs (https://mustangforums.com/forum/4-6l-1996-2004-modular-mustang/460393-plugs.html)

I finally got around to installing new plugs today. The old ones were white. I have about 700 miles on them since installing my procharger. I am still running a canned tune, which I thought was rich. They were stock plugs pretty worn out and gapped way to big for forced induction. When in the boost about 4000 rpms and up I got a light shuttering. I figure this to be due to the plugs. I installed new ones 2 steps colder and gapped at 35. Could the white/grey color be due to the plugs or am I just way to lean?

Could the wrong heat range cause this?

Get a wideband hooked up ASAP. It sounds like you are lean. Take it to a dyno and get it tuned correctly.