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Thread: my worst fear, might've finally happened...

  1. #16
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    I had a misfire suddenly and it turned out to be an arcing spark plug wire. Always try the easiest solution first. although I would assume the shop already checked those things first. you can also check injectors by holding a screwdriver to one and the other end to your ear and listen for a rhythmic "tick tick tick tick" sound.

  2. #17
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    Protege5

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    Valves have been known to fail from time to time. Not very often, but it happens.

    If you verify low compression, then you can often get in the cylinder with a borescope and confirm that the valve is busted.
    2002 Protege5 5 Speed, Pure White, FSZE Swap, Konig Incident 17's
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  3. #18
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    Yeah I feel you but they said they tested all 4 and nothing. I'll try to do this tomorrow
    2002 Mazda Protege5 Pure White

    MP3 Flashed ECU | Mishimoto Radiator/Shroud | MS Door Sills & Shift Knob | OBX Short Shifter with CorkSport Bushings | Goodridge SS Brake Lines | CorkSport 3rd Link Mod | MPV Wiper Stalk & Tribute Nozzles | S2K Antenna | Cabin Air Filter Mod | Rear Bumper Guard with Matte Black Rear Valance | 205/55R16 Kumho Ecsta 4XII on 03 P5 Wheels

    Among the fair amount of maintenance work done.

  4. #19
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    protege5

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    Quote Originally Posted by wrathofpaul View Post
    although I would assume the shop already checked those things first.
    Never assume anything. "the shop" is only as good as the guy that pulls the ticket and works on your car. I worked at a dealership and knew "master techs" that I wouldn't let work on my bicycle.

    Also, a noid light is much better than listening through a stethoscope or screwdriver. most people don't know what to listen for. But anybody can watch a little light flash.

    And agreed with Mr Giggles. While it is always a possibility for a valve to fail, it's extremely rare. I would really be surprised if this was your issue. Valve seats failing is much more likely, with wear and high mileage (especially if the engine is driven hard/high RPM) or valve adjustments are not done on schedule, the valves can beat the seat out of the head. Fix is a valve job or replace the head. I had a 4runner years ago that had this happen. $75 for a new head at a junk yard, adjust everything to spec and I never once had a problem with that truck.

    And boroscopes are great. You can buy one on Amazon for around $25 that's wifi and use your smartphone or ipad as the display screen. Much cheaper than the $500 ones years ago from the snap-on guy because nobody else had them.

  5. #20
    ......................... i12drivemyMP5's Avatar
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    IMO, if there was a broken valve floating around inside the motor there'd be all kind of ruckus and something imploding or exploding before you drove any 80 miles. I'm trying to imagine that valve head bouncing around in the cylinder and just letting you keep driving along with nothing but a flashing light on the dash...........seems extremely farfetched. If any valvetrain item breaks the car isn't going anywhere except to the side of the road pretty much instantly.......................discuss

  6. #21
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    Quote Originally Posted by i12drivemyMP5 View Post
    IMO, if there was a broken valve floating around inside the motor there'd be all kind of ruckus and something imploding or exploding before you drove any 80 miles. I'm trying to imagine that valve head bouncing around in the cylinder and just letting you keep driving along with nothing but a flashing light on the dash...........seems extremely farfetched. If any valvetrain item breaks the car isn't going anywhere except to the side of the road pretty much instantly.......................discuss
    If anything there will be a slight tick on that valve, they seldom close all the way if there is a seat issue, that creates excess clearance and noise.

    The one time I've seen a broken valve in person, there was just a piece missing, like in the video below.

    https://www.youtube.com/watch?v=xyY5xt4LmPw&t=341s

    You are right though, there would be a misfire all the time, this isn't a "once in a blue moon" issue.
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  7. #22
    ......................... i12drivemyMP5's Avatar
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    Well, if a tiny screw off a butterfly valve from VICS makes the amount of noise and damage it does, I can't imagine the crazy that would happen if the end of the valve was bouncing around in there or even a piece off it. That shit would break plug end and would not get past rings. Drop the exhaust manifold and see what's there. It would have to go somewhere and the car would not run anything near normal enough to drive 80 miles....not that I could imagine in any way.

  8. #23
    The Diagram Dude pcb's Avatar

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    The screws on the butterfly valves are on the intake and would get drawn into the combustion chamber.

    A little piece of exhaust valve would most likely be blown out of the cylinder before it had a chance to fall in.

    However, I still don't think the cel would only flash after driving a while with no compression on cylinder #2. (and it may be on at first because of his other codes)
    And his car would run like crap,.. Not just in limp mode.

    I still think he just needs coils, plugs and wires especially if his compression is good.
    Last edited by pcb; 11-28-2018 at 11:49 PM.
    The Diagram Dude

  9. #24
    The Diagram Dude pcb's Avatar

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    Quote Originally Posted by stormkyori View Post
    Yeah I feel you but they said they tested all 4 and nothing. I'll try to do this tomorrow
    When you say "nothing", do you mean they found nothing wrong with the cylinder or that there was no compression ??

    If they found nothing wrong with the cylinder, and you have full compression, then there is something else wrong with that cylinder.

    If you had been misfiring for a while before the test you could have completely fouled the cylinder and a new coil, plug and wire may not be able to fire in it.

    (carbon buildup reduces the volume of the combustion chamber and increases pressure).

    Everything still boils down to a compression test.
    Last edited by pcb; 11-28-2018 at 11:45 PM.
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  10. #25
    The Diagram Dude pcb's Avatar

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    You could rub your codes (or disconnect your battery for ten minutes) then drive it and see if the cel comes on right away and if it's flashing and see how long it takes.

    Both codes P0138 and P0140 need two drive cycles to turn on the cel.
    Last edited by pcb; 11-29-2018 at 12:32 AM.
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  11. #26
    Damian Dpwhitehead1's Avatar
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    Quote Originally Posted by pcb View Post
    The screws on the butterfly valves are on the intake and would get drawn into the combustion chamber.

    A little piece of exhaust valve would most likely be blown out of the cylinder before it had a chance to fall in.

    However, I still don't think the cel would only flash after driving a while with no compression on cylinder #2. (and it may be on at first because of his other codes)
    And his car would run like crap,.. Not just in limp mode.

    I still think he just needs coils, plugs and wires especially if his compression is good.
    Actually these screws and flaps donít necessarily get drawn in but itís possible. A while back I found this issue for Dubs car. Valve screw fell out and kept smacking the spark plug wire shut- this will Immediately cause a flashing cell
    Be happy!

  12. #27
    Registered Member Catzilla's Avatar

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    Quote Originally Posted by stormkyori View Post
    I took it into the shop and they deducted that apiece of a valve is broken off. They said for the work to be done and thats not including misc part or other things they might find wrong along the way to an amount of $2k so at this point i think I might be looking at a new engine
    Quote Originally Posted by stormkyori View Post
    According to the shop, they used diff coils and plugs to test the other cylinders and it was just the #2 that kept giving an error.
    Quote Originally Posted by stormkyori View Post
    Yeah I feel you but they said they tested all 4 and nothing. I'll try to do this tomorrow
    Never go to that shop again.

    It's elementary mechanics that a broken valve is properly diagnosed with compression test and boroscope, not by switching coils and plugs around hoping to cure a misfire. This shop is plainly trying to bend you over.

    Subscribed for compression test results.

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