3rz running rich

[cantaloop]

Posted this in the 3rz only thread but i got nothin so figured i'd repost. Im a 3rz 4runner owner and mine has been running very rich for a while now. You can smell it while driving around town with the windows down, it's definitely gas. Thought it was my exhaust leak at first so i replaced my manifold with a header. Stopped the leak but still ran rich. So i replaced my upstream o2 sensor, cause i had a P0136 show up. Still didnt fix anything. Rear o2 was replaced when i got the truck so no issues there. What else could be causing it to run so rich?


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[Kanoe]

What mileage are you at? Is it running well? Is it possible you could have an exhaust valve clearance too tight and not sealing properly? -as in some fuel escaping past an exhaust valve on the compression stroke? I would think you would notice something in driveability though...

This is just a guess but the exhaust valves are a known issue on this engine.

 

[cantaloop]

It runs pretty good, idle is steady around 650 when in drive. I can hear a ticking when at higher revs that sounds like it could be valve related, doesnt sound like an exhaust leak. May have smoked a valve when i had a big exhaust leak that i didnt fix for 8 months.


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