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Friend of Warren
Join Date: Oct 2000
Location: Lincoln, NE
Posts: 16,492
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MFI-Check out my sparkplug!
 As you can see the tip of my spark plug is what I think is a good brown (although a bit dark) for a MFI system. However the rest of the plug is black and sooty indicating a too rich mixture. When I lean the mixture out I get a white tip, but still the rest of the plug is black soot. Is this normal for an MFI system? If not, what should I do? NOTICE!!!! I have and follow all the MFI tech articles including "Check, Measure and Adjust" Thanks Kurt V 72 911E |
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08-07-2001, 05:50 PM
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Registered
Join Date: Dec 1999
Location: TX USA
Posts: 9,804
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Kurt,
What specific plug is that ... BP7-ES, B8-ES? All I see is black soot ... the metal parts don't get read, just the insulator, and that one is TOO RICH, TOO RICH, TOO RICH!!! Lean it out! ------------------ Warren Hall 1973 911S Targa 1992 Dodge Dakota 5.2 4X4 parts hauler [This message has been edited by Early_S_Man (edited 08-07-2001).] |
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08-07-2001, 07:17 PM
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Registered
Join Date: Feb 2001
Location: Mill Valley, CA
Posts: 204
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That plug is way to rich. Start one click at a time on the high end adjustment.
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08-07-2001, 07:22 PM
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Friend of Warren
Join Date: Oct 2000
Location: Lincoln, NE
Posts: 16,492
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Warren, the plug is a BP7ES. If I lean the mixture out more the electrode becomes white and the insulator is still black. I'm afraid that I might cause some harm to the engine with the plug in that condition (white tip, black insulator) Should the electrode and the insulator both end up being the same brown color? Thanks!
Kurt V 72 911E |
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08-08-2001, 05:18 AM
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Registered
Join Date: Dec 1999
Location: Novato, CA
Posts: 4,740
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With unleaded all plug insulators should be white.
Joe Garcia |
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08-08-2001, 08:29 AM
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Registered
Join Date: Dec 1999
Location: TX USA
Posts: 9,804
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Kurt,
You can't really read the full-load richness of a set of used plugs ... the idle and part-load running conditions mask the condition of the plug's highway/upper rpm characteristics. To actually test mid-range and higher mixture richness, you would have to install a brand new set of plugs in a warmed-up engine, then do your highway or track testing, and switch off the engine for a coast-down without power! Immediately pull the plugs and 'read' them ... somewhat of a tedious process, admittedly! ------------------ Warren Hall 1973 911S Targa 1992 Dodge Dakota 5.2 4X4 parts hauler [This message has been edited by Early_S_Man (edited 08-08-2001).] |
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08-08-2001, 08:51 AM
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