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Discussion Starter · #1 · (Edited)
Just inspeced my Ignition plugs few days ago(Rav4 2006/I4), Iridium based on Spec in manual I changed it 1.5 year ago around 20,000 KM since then I drove it. The top of the Plugs are Black and deposit is noticeable. ( that supposed to last at least 100,000KM ).
I remember I chaned my Corolla 2004 at the same time with Rav4, almost same milage drivoven since then. When I look at the Corolla ones, that is Beautiful, looks like a New Plugs(No smoke,No Blacked or deposit on them) after driving same milage!!!!
I know I4 engine burns oil, but What I could do to avoid that black plugs or improve that? any thing to adjust? I already added Seafoam to my tank and clean the Throttle after my inspecton.
to me the Design of 2004 Corollas engines are way better and healthier compare to Rav4s (2006)

Any input is appreciated :)
 

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Black on the plugs usually means it's running too rich. But that should set an O2 sensor code. Are there any codes or a CE light?
 

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if oil is getting by the rings and into the combustion chamber wouldn't that be the same as running rich? since you have an oil burner i bet that extra oil is just not burning complete in the cylinder causing your deposits...unfortunately i think the only way to solve this is for an engine rebuild...
 

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Okay, if your fuel mileage hasn't suffered I wouldn't sweat it.
 
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if oil is getting by the rings and into the combustion chamber wouldn't that be the same as running rich? since you have an oil burner i bet that extra oil is just not burning complete in the cylinder causing your deposits...unfortunately i think the only way to solve this is for an engine rebuild...
This makes total sense. How much oil is it using over 5,000 miles?
 

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Using plugs with a step hotter heat range might help burn off oil deposited on the center electrode.

A close up picture would help us to see the problem whether oil or fuel deposits
 

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I can tell more from a photo. If the black is only on the metal shell, then all is ok. If the black is on the porcelain, it is either running too rich or consuming oil. Oil usually causes fluffy deposits.
 
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Discussion Starter · #9 ·
Unfortunately I have not taken any picture and I already cleaned the black of the plugs, but it was not black on the sharp head, it was mainly on the cylinder side of the plug( the ring shape).
 

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Discussion Starter · #10 ·
Using plugs with a step hotter heat range might help burn off oil deposited on the center electrode.

A close up picture would help us to see the problem whether oil or fuel deposits
How I can say the plug is hotter heat range? any indicator on the package?
 

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Double check the heat range of the plugs you installed, perhaps they are too cold? Another possibility is a stuck open / faulty thermostat preventing the engine from fully warming up? I think the latter would cause an error code though.
 
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