Need help reading these plugs
#11
Well obviously a spark plug is not a direct indication of afr, and with the tools and software available to us today, there's really no need, but, if you've been doing it for years, and know what to look for, a spark plug can be a useful diagnostic tool. I'm pretty sure that the OP has tuning software from what I remember, and was looking for an answer as he's not used to reading spark plugs on a daily basis as someone who has been turning wrenches and tuning automobiles for a living their whole life might. I'm guessing that he saw the tannish color and took it as an indication of a problem, and was relieved to hear that what he saw was totally normal. Also, it's been my experience that an engine doesn't need to be super rich to leave carbon behind...rich enough to notice negative fuel trims, but not rich enough to trip a P0172 or 175.
Now trying to read in iridium plug is a completely different story...
Now trying to read in iridium plug is a completely different story...
#12
The only thing you can tell by looking at the tips of the insulators is if the heat range is OK.
You need lights and magnification to look down where the insulator meets the metal body of the plug to check AFR.
Read this and raise your level of consciousness:
http://www.strappe.com/plugs.html
You need lights and magnification to look down where the insulator meets the metal body of the plug to check AFR.
Read this and raise your level of consciousness:
http://www.strappe.com/plugs.html
The blackened plugs that I've pulled out of numerous vehicles with faulty fuel regulators, bad O2 sensors, incorrect ignition timing, etc. would have to say different...I learned this about 25 years ago ...
Well obviously a spark plug is not a direct indication of afr, and with the tools and software available to us today, there's really no need, but, if you've been doing it for years, and know what to look for, a spark plug can be a useful diagnostic tool. I'm pretty sure that the OP has tuning software from what I remember, and was looking for an answer as he's not used to reading spark plugs on a daily basis as someone who has been turning wrenches and tuning automobiles for a living their whole life might. I'm guessing that he saw the tannish color and took it as an indication of a problem, and was relieved to hear that what he saw was totally normal. Also, it's been my experience that an engine doesn't need to be super rich to leave carbon behind...rich enough to notice negative fuel trims, but not rich enough to trip a P0172 or 175.
Now trying to read in iridium plug is a completely different story...
Well obviously a spark plug is not a direct indication of afr, and with the tools and software available to us today, there's really no need, but, if you've been doing it for years, and know what to look for, a spark plug can be a useful diagnostic tool. I'm pretty sure that the OP has tuning software from what I remember, and was looking for an answer as he's not used to reading spark plugs on a daily basis as someone who has been turning wrenches and tuning automobiles for a living their whole life might. I'm guessing that he saw the tannish color and took it as an indication of a problem, and was relieved to hear that what he saw was totally normal. Also, it's been my experience that an engine doesn't need to be super rich to leave carbon behind...rich enough to notice negative fuel trims, but not rich enough to trip a P0172 or 175.
Now trying to read in iridium plug is a completely different story...
The part about leaving carbon behind & (-) fuel trims is interesting.
You reminded me I left my old Iridium plugs at my tuner's.
He threw them out by now I'd think. It's been ~2 wks. since my tune.
I wanted to read my plugs in detail. Only one looked a teeny, tiny bit oily on threads. Any guesses? It was #7. I keep hearing of horror stories on #7, if there's 1 cyl. that'll be an issue on LS motors, it's that one. Anyway, what makes reading an Iridium plug different, other than their longer service life?
#14
PT's Slowest Truck
iTrader: (19)
Originally Posted by fastnblu
The part about leaving carbon behind & (-) fuel trims is interesting.
Originally Posted by mhotrodscooter
I thought when reading plugs, you must go WOT & then throw it neutral & kill the motor.. To get the reading. Is this still true?
Last edited by budhayes3; 10-09-2010 at 08:42 AM.
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