Solved oil fuel dilution with computer reboot.

I've had oil that smelled like fuel. I was siphoning out oil at 4oz per 1000 miles as contaminated oil/fuel seemed to float after days of prius sitting.

After noticing no charge arrows on initial engine startup while prius is in park. I decided a reboot of all prius ecu's was nessary.. Bytheway scanguage showed about 11 amps charge after engine start while in park but
multifunction display showed no arrows at all.. (suspicious).

So I drove to a nice level place as fuel tank ecu requires level while calibrating fuel ecu...
I put car in neutral and pushed forward and backward about a foot or two and with equal force to move car
forward and backward. I belive ground and car is level.

I then unpluged aux 12 volt battery for about 2 to 3 minutes ( there are two wires that plug into positive side
battery terminal ) .
With everything off.Tthe small size wire (voltage sense wire) should be unpluged first.
Then the large diameter wire should be disconnected second..

When reconnecting the large wire should be connected first and the small wire secondly.

With the 12v batt disconnected i did turn on the parking lights to drain off any remaining charge from system.

After reconnecting 12v aux batt. and putting car back together.
I drove off noticing an immediate difference. Prius now accelerates wonderfully with hardly any gas peddle depression.

Monitoring short term fuel trim with scanguage is at +6 for the first quarter mile, +5 the next quarte rmile
and fell to zero after about 1.5 miles... Before short term fuel trim was mostly -2,-3,-4 hardly ever seen positive short term fuel trim numbers if ever !

After about 20 miles city driving and now getting 67 mpg instead of 54 mpg car seems extremly smooth and responsive.. I smelled the oil (after 20 miles) not a trace of fuel smell!

Its now been three days since ecu's reboot and no trace of fuel smell in oil..

I notice negative numbers indicate fuel added (rich) positive numbers fuel mixture lean as seen on scan guage.
Long term fuel trim is at + 4 and didn't seem to change after reboot.

When accelerating short term fuel shows + rich fuel mixture. When cruzing speed is established STF goes to 0
When climbing hill STF goes negative (rich). while going down hill SFT goes Positive (lean). There are exceptions to this.. but on the average while cruzeing level road STF is 0 .

i replaced 12volt batt about 2.5 -- 3 years ago and have not had and dead battery issues after replacing it.
Battery checks good under load and still seems new..

I lost programmed beep setting (seat belts etc) lost 3 segments of fuel gauge reading, power window settings trip a and b got zeroed as well as ave miles and accumulated miles on multifunction display zeroed after reboot but did not loose radio presets. (maybe I should have left battery disconnected longer ?

I had about 8 segment on fuel guage before reboot and only 6 segments after but I got slightly over 100 miles on that sixth segment as opposed to getting about 27 miles on the six segment..
Fuel guage seem back to normal after depleting that sixth segment.

Perhaps the prius should be rebooted once in a while and definately after dead battery, jump starts, or odd behaveur...

Sorry for the crap spelling..

 

I believe the fuel tank calibration process recommends near full tank of gas to do it properly...
(Checking my notes say 1/4 to 3/4 fuel in tank to due fuel tank calibration)
And I believe removing 12 volt battery source reboots and recalibrates all ecu's including sensors..

So if you should do this remember car should be level and gas tank should be 1/4 to 3/4 (old prius-chat post ).

I did my prius reboot (ecu reinit, reset) with car warmed up. I had good results but dont know of any official information yet for rebooting prius.. But I believe strongly all ecu's should be reset at the same time...as you could probably reset individual ecu's by simply pulling associated fuse..but best to do all at the same time..as they all communicate with each other...

 

Now I'm thinking my prius maybe running to lean as other prius's that I've smelled oil had smell of fuel (two others gen-three and
prius-c)
and my oil does not smell of fuel anymore...also when I rebooted prius it was the morning of the first 83 degree day in vegas..
Perhaps first hot day burned off fuel smell from oil... but fuel smell never burned off through the entire summerr last year..

Too lean fuel burn will result in melted piston and valves under load. Engine components rely on additional unburnt fuel to cool parts.

Perhaps my total system reboot should have been done on cold prius....???? Perhaps I should have cleaned MAF (mass air flow sensor).
My MAF has never been cleaned at 54000 miles..
My reboot was done about a mile from house and engine temp was probably only 150 degrees not fully warmed up..

All this attention to by prius Is because I love it so much...Will all my intentiveness eventually kill my special prius?
I can never let dealer or other mechanic touch any of my cars.. This way I know the cause and results of what I have done..

Does anybody's prius oil not smell of fuel or is it just mine now..

If anybodys prius oil does not smell slightly of fuel how many miles are on your oil ?

 

Here is a follow up after resetting ECU's about 6 months ago.
My last oil change at 5000 miles was the cleanest oil I ever drained from my Prius!
The ecu reboot/reset fixed my fuel diluted oil problem and I stopped siphoning out top oil.
I have got 3000 miles on my current mobile 1 5w-30 extended oil . no fuel smell in oil.