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2002 Mazda Tribute "coils"?

I have a 2002 Mazda Tribute V6 with 151K. My check engine light has come off and on for quite a while now, mostly it would come on when it rained and then go off when the weather cleared. When it was on, the engine would sputter or misfire. I first had Auto Zone hook it up and they said it needed its plugs and wires changed. No problem. I took it in to a repair place and was informed that I don't have plugs and wires, but something with coils and that since it was impossible to determine which coil was bad, all would have to be replaced at a cost of $1500. I then took it to another repair place and they said the same thing. Now I have seen some discussions regarding this same thing and apparently some people have been able to identify a specific coil. At this point my check engine light is now on all the time and I'm really worried about doing terrible damage but I honestly can't afford $1500! I would appreciate any suggestions!
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Comments

  • You need a mechanic with better tools. The right computer interface can plug in and read the system while it's running, and tell which cylinder(s) is(are) misfiring, and replace just what's failing, not everything.
  • I agree with chaissos. You're not talking to the right mechanic.

    Please elaborate about where you took your Tribute. Are the places you visited part of a national chain? Did you consult a Mazda dealer? Have you talked to an independent mechanic? We need to know these things.

    If the light is on for a misfire, the computer should tell the mechanic which cylinder is misfiring. It's not rocket science.

    Whoever said you don't have plugs and wires is partially incorrect. Your Tribute has spark plugs, and it has wires, but it probably doesn't have a traditional ignition coil.

    I believer your Tribute has a "coil-on-plug" ignition system.

    My suggestion? Find a good independent mechanic. Stay away from the national chain shops, or the tire stores, oil change franchises, etc. You need a mechanic, and when you find one you will be amazed at how simple it is to get your vehicle working properly again.

    You will, of course, have to write a check, but if you find a good mechanic it will be worth every penny.
  • You should not rely on AutoZone for a diagnosis nor should you assume part of their job is to provide a diagnosis. Their job is to scan the car and provide a code, or codes, to you. Nothing more.

    I'm in agreement that you likely do not need all of the coils changed en masse.

    Questions though.
    Does this car have the original spark plugs in it? If so, ouch. That can be a coil killer.

    What code or codes are shown? Without knowing the codes we can't even begin to make an educated guess.
  • Oh wow. Thank you for all the feedback. I will go look and find the information I received regarding the codes. I cannot remember the first place I took it to, but I don't think it was a national chain. The second one was a small independent mechanic who was performing my vehicle emission inspection. I have not taken it to the dealership yet. Thank you for the input, and I will update later with more information.
  • I found the print out from the diagnostic machine. It says: "Cylinder 4 misfire condition detected. Probable causes: lean air/fuel ratio; weak ignition system; engine mechanical condition; vacuum leak affecting one cylinder."
    As far as I can see on the slip, there are no codes referenced.
    I did find another document that looks like it may have been from one of the mechanics noting an ignition coil, spark plugs, ignition cables and ignition timing/idle speed.
    Does this help?
  • Ignition timing or idle speed would not be the cause of a Cylinder 4 misfire.
    What should be done is to remove the spark plugs and run a compression test on all cylinders as a first step to make sure there are no engine mechanical faults. The readings should all be close to each other and considering the mileage on the vehicle, and assuming the engine is in good condition, you should see around 170 PSI on each cylinder.

    The spark plugs should be replaced if pressures are good and the spark plug contact surface inside the coil boots should be inspected for corrosion, etc.

    You should avoid the shop that recommended replacing all of the coils. An expensive shotgun wild guess at a problem without even verifying there are no mechanical faults first is not a smart move.
  • edited June 2011
    So from reading the above comments I have spark plugs AND coils. Ok. I'm printing out this discussion and taking it with me so I have talking points and don't sound like a crazy person to the mechanic.
    Should I take it to the dealer or just get a recommendation for a good independent mechanic?
  • Yes, you have both spark plugs and coils. The spark plug is the item that creates the elctrical arc (spark) that ignites the fuel in the cylinder, creating combustion and power. The coil is a device that generates enough voltage to jump the spark plug electrodes creating the spark. 12VDC won't just that big of a gap in that environment. The coil does this by creating a magnetic field (via a coiled wire) around its iron core and at the prper time allowing it to collapse into the core, creating a voltage "spike" of many thousands of volts.

    In BC (Before Computers) there was one coil. The high voltage spike was distrbuted to each sparkplug at the appropriate time by the distributor. The "appropriate time" was determined my mechanical parts in the distributor, the rotor and contacts on the distributtor cap. On modern engines, each individual sparkplug has its own private coil. The timing can be controlled by the comuter, so there's no longer a need for the distributor's mechanical parts. Placing a coil right on each plug also eliminates the sparkplug wires, which were prone to the insulation breaking down as they aged.

    Um, I have a question: are these the original sparkplugs? With 151,000 miles on them? If so, I think I know why your #4 cylinder is misfiring. I'll bet my morning muffins that the electrodes are eroded. That leaves too large a gap for a reliable spark. I've attached a link with pictures of sparkplug electrodes so you can see what they look like.

    http://www.ngksparkplugs.com/tech_support/spark_plugs/faqs/faqread.asp

    I hope I'm right.
  • Thank you for the explanation and the visual aid! As far as I know yes, these are the original spark plugs. When I bought the car it was 2 years old so I doubt they would have been replaced before I purchased it and as far as I can remember, I don't believe I've ever had them replaced. From what everyone is saying, the spark plugs are definitely what I need to try first (and hopefully last!)
    Thank you!!
  • It's time for the maintenance schedule lecture In addition to resolving this issue, you need to examine the maintenance schedule for this vehicle and get it up to date. That would include fluid changes (including ATF), filter changes (more than just oil changes). Your spark plugs are most likely 90K to 31K overdue and that is the most likely basis for your problem. Bringing your maintenance up to date will extend the life of your car.
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