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Possible Water In Gas Tank Causing Power/Acceleration Issues?

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Prius_Cub, Mar 8, 2015.

  1. Prius_Cub

    Prius_Cub Member

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    Update: Hesitation and power loss have returned as of 3/22/2015. I removed all four spark plugs and found that the spark plug on the driver side of the engine, or side closest to the inverter, and its coil pack were covered in dried/sticky oil with no loose oil present around them. Pics added to new post #11 of coil pack and spark plug.

    Sorry if this may have already been covered but I couldn't find anything that really matched the symptoms I was having this afternoon on the way home from work. After letting the engine idle for about a minute to get through Stage 1, I pulled out of work but noticed I kept hearing a slight whining from the inverter (radio was off and windows were down) while going uphill on the road out of our parking lot. Speed was in the range of 25 to 30 MPH.

    Torque showed I was pulling between 10 and 20 amps from the HV battery but what I noticed that was REALLY weird was that the timing advance gauge showed I was running around 2 to 3 degrees (?) instead of normally being around 13 or 14+ depending on how quickly I'm accelerating. And the more acceleration I demanded, the the more amps were coming from the battery and the RPMs on the engine would go up, but the timing advance still remained below 10 degrees. I didn't hear any knocking but I could definitely feel the lack of power.

    Things returned to normal after a 1/4 mile after reaching a flat road on the way to town and the timing advance was where I was accustomed to seeing it at between 14-18 degrees. But the symptoms kept coming and going especially after a stop or after going up or down an incline and then recovered once things leveled out. No check engine light came on at all and the engine shut down fine but it was a bit...bumpy to put it, when it would start back up.

    On a hunch I decided to purchase some Seafoam fuel system cleaner/treatment and topped up with gas from a different gas station than the last one I bought from. And after a short drive, everything was normal, no more lack of power, no more bumpy starts from the engine.

    Am I right to assume I might have bought some bad gas or just had a bit of water in the tank? Just a little worried at this point that it could be something worse.

    tl;dr

    Driving home I noticed a loss of power that intermittently came and went and seemed to coincide with climbing or just after descending inclines and went away so long as I was on fairly level roads with no stops. No check engine lights or odd noises other than the sound of the inverter during these periods.

    Thanks in advance for any insight!
     
    #1 Prius_Cub, Mar 8, 2015
    Last edited: Mar 22, 2015
  2. Easy Rider 2

    Easy Rider 2 Senior Member

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    First you said that everything was back to normal.......but then added this at the end.
    Which is it ??

    Could be due to bad fuel but strange things happen when the 12 V battery fails too.
    If it is original and 6 years old, I think I'd be getting a new one.
     
  3. Prius_Cub

    Prius_Cub Member

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    Sorry, the tl;dr was shorthand for too long; didn't read, just for a quick summary at the end. The 12 volt was replaced in 2012. Holds steady at around 12.5-12.6 volts at rest and around 12.2 to 12.3 volts in IG-ON.
    edited to correct statement as to what state the voltages were measured in
     
    #3 Prius_Cub, Mar 8, 2015
    Last edited: Mar 8, 2015
  4. Easy Rider 2

    Easy Rider 2 Senior Member

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    What ? Which is it ??

    Those numbers could mean trouble depending on how long they were taken after a full manual charge was done.

    At 70 F, an AGM that reads 12.3 with no (or minimal) load would be about 50% discharged.
     
  5. Prius_Cub

    Prius_Cub Member

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    Sorry, realized my error, just after I had posted! These were measured recently after using Jeff's grid charger on my HV battery after sitting 24 hours and this was over a weekend when we had ambient temps peaking in the 30's. I'll put it on charge just to be safe.
     
  6. Easy Rider 2

    Easy Rider 2 Senior Member

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    There is an edit function available.

    Whatever did or did not happen to the HV battery has no bearing on the 12 V system........unless maybe you left something like dome lights on for a long time while tinkering with it.
     
  7. Prius_Cub

    Prius_Cub Member

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    Thanks, I had already edited it. :)

    Sorry, I'm not suggesting that it had anything at all to do with the HV battery or grid charger. Just describing the situation the voltages were measured in.

    This morning, everything seems completely normal after putting Seafoam in. I was just a little panicked about what happened and I tend to over explain things. But I do thank you for your suggestions Easy Rider 2!
     
    Landon51 likes this.
  8. wjtracy

    wjtracy Senior Member

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    We don't hear too much about water in gasoline these days, I think because the E10 10% ethanol in the gasoline does a good job of dissolving the water into the fuel. Basically how the Seafoam probably works. I forget where you live Cub but maybe consider trying TopTierGas.com stations. If you live where there are a bunch of smaller gaso brands, maybe more chance for a fuel issue. The last report of fuel issue we had (might have been Lexington VA if I recall) the guy found out he actually had a very lose spark plug. Not too many documented fuel issues these days. Couple rare cases of diesel filling mistake, but that stops you immediately.
     
  9. Easy Rider 2

    Easy Rider 2 Senior Member

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    I personally am not impressed by "top tier" gas marketing and especially not by Seafoam.
    It is overpriced compared to other products that have similar claims that perform better.

    I AM in favor of a dose of Techron every oil change though; about 8 to 10K miles.
     
  10. Prius_Cub

    Prius_Cub Member

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    Thanks wjtracy, I'm down in Radford, VA. I bought gas at a BP station when I was in a hurry. Now...thinking back, while the car was in the body shop for a couple weeks. It may have been low on gas so it could be from that.
     
  11. Prius_Cub

    Prius_Cub Member

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    Well, here I am revisiting this issue since it came back. I finally decided to grin and bear it and removed all four spark plugs to check them to see what the heck was wrong since I had the intermittent hesitation/lack of power again on my way home from work this evening. The only one I found that looked wrong was the spark plug on the driver side of the vehicle, or the side nearest the inverter. The other coil packs/boots were a clean gray color but this one is covered in sticky oil residue and so was the spark plug which I wiped off but at this point my guess is that its safe to say I need a new coil pack and new spark plug? What do you guys and gals think?

    One thing, I haven't noticed any smoke or smell of burned oil coming from the exhaust in the morning when leaving for work. I normally start my car and let it warm up while I move my roommate's vehicle out of the driveway so would think I'd have noticed if I had been burning a significant amount of oil. The dipstick shows I'm at 3/4 up between the min/max marks on it which is normally where I aim for when changing oil. I suppose its possible I may have overfilled on the last oil change but hadn't noticed anything else odd except for this occasional hesitation/power loss lately.
     

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  12. nh7o

    nh7o Off grid since 1980

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    The question is, where did the oily deposit come from? I would replace the ignitor, but I would guess something else is not right. Injector?
     
    #12 nh7o, Mar 22, 2015
    Last edited: Mar 22, 2015
  13. Prius_Cub

    Prius_Cub Member

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    I would do that but the problem is that its not throwing the check engine light or any codes. I was hoping it would throw a code to match up with my "smoking gun" cylinder but it didn't, not even after I wiped it off and put everything back together and ran for a test drive. Even pushing the accelerator halfway down and beyond, it wouldn't trigger anything to happen other than I could watch the timing advance bog down below 10 degrees and the amps coming out of the battery ramping up to compensate.
     
  14. Prius_Cub

    Prius_Cub Member

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    After searching online for why oil may have gotten into the spark plug well, it seems I may be in for replacing the valve cover gasket and spark plug tube seals to fix/prevent that from happening again.
     
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  15. nh7o

    nh7o Off grid since 1980

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    OK, that sounds like no easy fix. A rare occurrence, as far as posters on PC have reported.
     
  16. Prius_Cub

    Prius_Cub Member

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    I'm not fond of the idea of doing that, but I didn't notice any loose oil in the well and nothing soaked up into a towel I pushed into it so maybe it was a single event that fouled the igniter. I think for now I may just replace the coil igniter and that spark plug and give about 500 miles and see if there is any oil buildup on the new igniter and if so, go for the gasket replacement.
     
  17. 00-00

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    Seeing that spark plug with the burnt oil residue brings back memories from the 70's when that was a relatively common occurrence. The 1600 cc engines had the rubber spark plug tube seals that over time, lost their sealing ability, and looked exactly like yours.
    My guess is that your coil may very well be operating as it should, but I may be wrong.
     
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  18. Prius_Cub

    Prius_Cub Member

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    If only it would code so I could move it around and see where the problem stayed or went when moving the coil. Unfortunately the ECUs seem happy to just use the battery to make up for the lack of oomph from the engine when I experience these transient losses of power. And it only lasts a few seconds (10-15 maybe) at best and recovers, especially once I'm up to speed or running at a higher RPM uphill.
     
  19. wjtracy

    wjtracy Senior Member

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    The other case I mentioned above the guy had DIY replaced his own spark plugs, and he did not use the correct plugs for the Prius, and one was apparently loose. In your case, we have the correct plugs, but do you think it might have been loose? I am thinking the oil residue came up through the spark plug threads? If so I'd be inclined to just tighten up and see how it goes.
     
  20. Prius_Cub

    Prius_Cub Member

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    I hadn't even thought about that, thanks wjtracy! Thinking back, when i replaced this particular one I do recall having trouble maneuvering the socket when reinstalling this one. I did put everything back together after making sure it was tight but the hesitation did come back. So I think I'll replace the spark plug itself first, see if it still occurs and then replace the coil.