Join Date: May 2004
Location: Morganville, NJ
Thanked 18 Times in 15 Posts
Fuel in oil, this occurs during engine operating conditions where the engine doesn't reach full operating temp. Not coolant temp, but OIL temp. If the oil doesn't get to a sump temp of at least 180F (other places will be higher) the moisture and fuel that is put into the oil via blowby past the rings isn't boiled off.
All engines have blowby to some extent, once it gets excessive, it'll show up as oil coming out a vent, usually into the intake ducting before the throttle body.
First, change the oil. And reduce oil change intervals, especially in cold conditions where the engine won't heat up fully. What oil are you running in the Yaris?
Any fuel vapors being drawn into the pcv system, during normal engine operation will cause a negative trim. Under loads greater than say 50% throttle, it should go +, some will show fixed 15% + by design or others will show open loop.
I have seen severely fuel contaminated oil cause an engine to run so poorly because the PCM pulls pulse width off the injectors due to the perceived rich running condition.
All Toyota engines iirc, have shim over bucket valve adjustment. They have no way to automatically have zero valve lash, it must be manually done. However, I've rarely ever seen a Toyota with radically out of adjustment valves, if at all. They aren't easy to do, as all clearances must be measured, and then recorded. The cams HAVE to come out. Then all shims are measured and values recorded, and NEW shims are installed in cylinders that are out of spec, with shims of the proper thickness.
It makes Honda's simple rocker arm lash screw/locknut set up work so much better.
Sapphire blue '04 V6 6 speed w/ full HFP, comptech ss, momo shadow, TL-S 27.2h/20 bars, intake spacer, retro chrome MH1 HIR2 highs, hella DE fogs, EBC Ultimax, subwoofer/amp, infinity rears, HD Radio, aux adapter, navi conversion.
Vermilion 1999 SVT F150 Lightning, Sylvania/Visteon Xenarc HID headlamps, '01 L turn/marker lamps, PIAA fogs, '01 up Bilstein shocks, all Pioneer speakers, Clarion subwoofer. All Redline fluids.
Silverstone 2003 Honda S2000, bone stock