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Old 11-18-2018, 06:05 PM   #10
142 guy
Board Member
Join Date: May 2014
Location: Saskatchewan, Canada

I think the point has been made that if you are trying to get a mixture read on the plugs they need to be fresh plugs and the plugs need to be pulled immediately after the full speed or part speed pass that you are trying to do the mixture assessment on.

That said, the insulator tips on #1 and #3 look reasonable. Depending on when they were pulled out of the engine (after a full throttle run or after 10 minutes of idling?) #1 looks like it might be a tad on the rich side of 14.7 and #3 a tad on the lean side of 14.7. Its hard to tell; but, #2 looks like it has some serious deposits on it compared to the others. Its hard to tell the color. If it is shiny and blackish then you may have excessive oil consumption on #2. If its not shiny and its dark you may have some fuel fouling / running rich which is lowering the combustion temperature. The reduced combustion temperature can result in deposits not burning off the insulator tip in normal operation. #4 is obscured by the Photobucket advertising.

Have you had your injectors cleaned and flow tested? #2 might be flowing more than you expect. Get the injectors cleaned up if they have never been cleaned and flow tested and then put a new set of plugs in and then do a full throttle run (if possible) and pull the plugs. That will give you an idea as to whether your full throttle fuel mixture is balanced (I am assuming that you have a wideband for monitoring the aggregate AFR of the cylinders). Put the plugs back in and drive for a few hundred miles and see if the deposits re appear on #2.
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