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Thread: Ignition Coil and ECM Question

  1. #1
    Registered Member

    2008 Mazda CX9

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    Feb 2019
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    ontario canada
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    1

    Ignition Coil and ECM Question

    Hey guys,

    So we bought our CX-9 about 4 months ago. It's been great so far apart from the transfer case having almost zero oil in it (glad i checked and re-filled before failure). Anyways, on our way back from a 400km trip, half an hour from home, the car lost power. I had the cruise control on and it kept trying to shift into a lower gear to get the car back up to speed. Anyways, i took it off cruise and could not accelerate, the more i tried the more it just slowed down. A few seconds later the engine light came on and started flashing. I then knew i had a misfire in one or more cylinders. We limped it home and i hooked up my scan tool and got the following codes:

    P0301, P0351, P0352, P0354. After some quick research, i found the tsb from mazda about the ECM and ignition coils. I finally got the time to take it all apart today, and found ignition coil #1 melted. the rest seem to be fine. Now, since they've never been done, i plan to get 6 new plugs and coils. BUT, i do not know how to test the ECM to see if it will just melt the ignition coil again. Is there a way to test to see if the ECM is good/bad?

    Now, the only issue i have is, if i do go ahead and order a new ECM (i found a seller on ebay who will pre-program it with your vin number), do i still have to go to the dealer to get the keys programmed or is that something i can do myself, and if so, how?

    I live in Canada, so shipping out my ECM for repair would take quite a while i assume, but i don't want to have to rip it all apart and spend the money on new coils again. Also, my cx9 is originally a USA car (if it matters). It has 118,000 miles. Lastly, its the switchblade key.

    Thanks

  2. #2
    Biggie T Skinny helbigtw's Avatar
    CX-3, CX-5 & CX-9 Moderator

    08 CX-9 GT Fwd, Bose/Nav, BSM,Compass/Homelink, Pwr Lift,Tow

    Join Date
    Feb 2011
    Location
    Pittsburgh, PA
    Posts
    2,104
    Sorry to hear about your troubles. I've never seen a tsb about ecm / coils ? I'm a 2008 with 101,000 miles (not km) and changed my plugs myself at 80,000 miles, but i've never had any ecm/coil issue. Maybe you just had a coil go bad and just replace coils and you're good to go?


    08' CX-9 GT FWD
    Gray Mica with Black Interior
    Nav/Bose/Sunroof/Bluetooth /Rack&Crossbars/BSM/Pwr Lift/Homelink Mirror/Tow Pkg/All Weather Rear Mats
    K&N drop-in filter/Centric E-Coated rotors & Centric Posi-Quiet Ceramics /2 Yakima ForkLift Bike Trays/ Weathertech front mats
    Tires: Nitto NT421Q
    Oil: Mobile One Full Synth & Mobile One Extended Performance filter
    Problems to date: Blower motor relays replaced once, intake manifold rear brace was missing from factory build, headlamp motors weak, windshield wiper plastic cap, rear strut leak.
    Mileage: 100k
    Location: Pittsburgh, PA
    Job: Material Damage Adjuster

    ...

  3. #3
    Registered Member

    2010 CX-9 GT

    Join Date
    Jan 2011
    Location
    Melbourne, FL
    Posts
    189
    Quote Originally Posted by fordcx9 View Post
    Hey guys,

    So we bought our CX-9 about 4 months ago. It's been great so far apart from the transfer case having almost zero oil in it (glad i checked and re-filled before failure). Anyways, on our way back from a 400km trip, half an hour from home, the car lost power. I had the cruise control on and it kept trying to shift into a lower gear to get the car back up to speed. Anyways, i took it off cruise and could not accelerate, the more i tried the more it just slowed down. A few seconds later the engine light came on and started flashing. I then knew i had a misfire in one or more cylinders. We limped it home and i hooked up my scan tool and got the following codes:

    P0301, P0351, P0352, P0354. After some quick research, i found the tsb from mazda about the ECM and ignition coils. I finally got the time to take it all apart today, and found ignition coil #1 melted. the rest seem to be fine. Now, since they've never been done, i plan to get 6 new plugs and coils. BUT, i do not know how to test the ECM to see if it will just melt the ignition coil again. Is there a way to test to see if the ECM is good/bad?

    Now, the only issue i have is, if i do go ahead and order a new ECM (i found a seller on ebay who will pre-program it with your vin number), do i still have to go to the dealer to get the keys programmed or is that something i can do myself, and if so, how?

    I live in Canada, so shipping out my ECM for repair would take quite a while i assume, but i don't want to have to rip it all apart and spend the money on new coils again. Also, my cx9 is originally a USA car (if it matters). It has 118,000 miles. Lastly, its the switchblade key.

    Thanks
    My memory of this is a little hazy, but I looked into this when I bought my 2010, and I think the coil/ECM TSB was for the 2007 model year only. There was a nasty failure mode that went like this:
    1. 1 ignition coil would go bad
    2. The bad coil would cause the ECU to fry itself (a trace on the PCB would melt)
    3. Some of the other ignition coils would possibly get fried by the now bad ECU

    Mazda changed the design for the 2008 and up to fix this.

  4. #4
    Biggie T Skinny helbigtw's Avatar
    CX-3, CX-5 & CX-9 Moderator

    08 CX-9 GT Fwd, Bose/Nav, BSM,Compass/Homelink, Pwr Lift,Tow

    Join Date
    Feb 2011
    Location
    Pittsburgh, PA
    Posts
    2,104
    Jal142 good memory. This is the first time I've ever seen a post about this on Mazdas247. My money is on a bad coil and not this crazy ecm issue. Hopefully just a coil worn out.

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