Checking the state of ignition coils from observation and using a multi-meter.

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by Ana Hernandez, Mar 1, 2016.

  1. Ana Hernandez

    Ana Hernandez Junior Member

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    Hi I've been trying to figure out how to use my multi meter to test the voltage and health of my coils as my mechanics recently suggested changing the coils due to hesitation or a "chunk chunk" noise when I start the car on "ready" mode THEN a few seconds after I see the engine kick in and I hear the "chug chug" or "cluck cluck" basically a rough sound when the engine is operating or when it is about to stop (for example after driving for a while and then coming to a stop).
    I went and removed the nuts this weekend and found oil/a dark grey muddy looking substance (this happened in the past within the years I've got with the car, but last time It was with the spark plugs so I changed them, although I had just changed them (by the mechanic) just about 6months previous to that). Can this be due to rain? Because last time it happened there was lots of rain, and now recently again.

    Here are some pictures I was able to get:

    So my final question would be, do you really think I have to change my Coils? and how do I use my multimeter to read the voltage of my current coils (what's considered a good voltage for these) as well as the voltage of the connectors?
     

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    #1 Ana Hernandez, Mar 1, 2016
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. Use paint thinner or other solvent to clean off each spark igniter.
    2. Carefully inspect the physical appearance of each. If you see any burn marks, cracks in the rubber or plastic, etc., then replace that igniter. There should be no corrosion on the wiring harness connector or on the high voltage terminal that connects to the spark plug.
    3. You cannot use a multimeter to determine whether the spark igniter is working properly. The test is to see whether it is producing a healthy spark, which requires you to insert a good spark plug into the igniter and ground the spark plug shell, while cranking the engine. Then you can see what kind of spark is being produced.
    4. The oil residue on the igniter in your first picture is either due to someone allowing oil to get everywhere on the valve cover when filling the engine oil; or else a leaking valve cover gasket which is allowing oil to enter the spark plug wells.
    5. If you see any water in the spark plug wells, that would be due to rain dripping on the engine and getting into the spark plug wells. The o-ring seal on the spark igniter is not very good and since the igniter is held on with only one bolt, may leak.
     
    #2 Patrick Wong, Mar 1, 2016
  3. Ana Hernandez

    Ana Hernandez Junior Member

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    Hey thank you so much for all the info and your time! You're awesome!
    I've just got a few questions and concerns as it'll be the first time I'm dealing with igniters. Here they go:

    1. Paint thinner or can I also use alcohol? 50% or 70%?
    2. I think I do see some little cracks on the plastic/gummy o ring of some of the coils. And I'm not sure if I see burn marks so I'll clean them first.
    3. Is there a video somewhere on how I can do that? When I do it will it produce sparks? (To the point of just scaring me a bit or to the point it can dangerous)
    4. I forgot to mention, I ONLY found this brownish oil in coil 1 & 4. So do you recommend I replace the valve cover gasket? (if so how many units would I need?)
    5. Are you referring to my o rings not being very good or in general with Toyota?
     
    #3 Ana Hernandez, Mar 1, 2016
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    1. You can use isopropyl alcohol although it may not be as effective in cutting through oil. I use 91% IPA for cleaning electronics components.
    2. Any imperfections, no matter how slight, are grounds for discarding the igniters. Buy the correct Toyota parts.
    3. I am not aware of a video. Yes, the whole point is to produce a healthy spark across the spark plug gap. It is not dangerous unless you decide to contact the spark with your hand or some other part of your body. The spark voltage is going to be 20KV or more.
    4. You can clean off the spark igniters but if you see that oily residue reappear, and you know this is not due to someone pouring oil on the valve cover, then you have to assume the valve cover gasket is leaking at those two cylinders. One gasket is required plus RTV sealant to seal a couple of spots at the front (which is the passenger side) of the engine.
    5. Your specific igniter's o-rings apparently would not be in good condition if you were to find water in the spark plug wells.
     
    #4 Patrick Wong, Mar 1, 2016
  5. Ana Hernandez

    Ana Hernandez Junior Member

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    Okay so I'm gonna go ahead and clean those igniters and see how it goes. I'll probably go ahead and order the gasket and sealant because I've experienced this nasty oil in the igniter area twice in the past nearly two years. Also in case I actually have to purchase them, they're about $100 each from Toyota, what would you say about going with after market standard ones? (Which have 4.5 and above ratings).
     
    #5 Ana Hernandez, Mar 1, 2016
  6. Patrick Wong

    Patrick Wong DIY Enthusiast

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    $73.97 at parts.com for 90919-02265:
    Parts.com® | Automotive Parts, Accessories and Merchandise

    I do not recommend buying aftermarket parts unless you are 100% sure you can resolve the issues yourself and have no need to rely upon Toyota dealer service. If you visit a dealer service department with a complaint, the first thing that will happen is that any aftermarket parts even remotely related to the complaint will be replaced.

    The quality of some aftermarket parts is suspect IMO. My personal preference is to buy only Toyota-branded parts, or as a reasonable alternative, parts from the original equipment supplier to Toyota with the OE brand instead of the Toyota brand.

    So as an example, an engine coolant pump with the Aisin brand would in my view be acceptable to a pump with the Toyota brand. That pump comes with the correct rubber coated metal gasket. I would not use a pump with a cheap paper gasket.
     
    #6 Patrick Wong, Mar 2, 2016
  7. Ana Hernandez

    Ana Hernandez Junior Member

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    Okay so I cleaned the coils with thinner, there are about 2 that have burn marks on the surface, the o rings aren't really good to be honest their separated from the coils. While cleaning them I checked on the spark plugs and they look pretty nasty also have some kind of liquid in them. I asked my mechanic of it was oil or water, he said the gasket should be good so it might be water that causes the dripping, (ps it usually happens when it rains) I also cleaned the spark plugs as well. I haven't been feeling rough engine hesitation or anything. I might leave those until I actually get a sign or I'm definitely convinced that they need to be changed, I also would rather whether Toyota parts or OE/OEM which tend to be more reliable. I did have a problem this weekend where the car fails to turn on, including any lights or accessories and the key itself but I rooted the problem to be from a bad connection of the positive terminal clamp in the aux battery and a broken piece of the brake control power box. After I tightened that bolt and taped back the plastic piece to the brake power box (which I thing has some sort of electrical connectivity to the box) it's been good. It's only been 2 days though. Sometimes the car doesn't respond to the key fob also, not sure what that might be.

    I'll post some pics of the job I did on the battery and what I mean by the plastic that broke from the brake power box next to the battery: image.jpeg
    image.jpeg
    image.jpeg
    In the final pic you can how I taped the plastic. It was very hard to align the 3 screws, maybe because one of the metal brackets that tightens on the ground has a bent form, maybe that's what initially caused it detach/break off.
     
    #7 Ana Hernandez, Mar 8, 2016
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