CYLINDER 2 AND 3 MISFIRE

Discussion in 'Mazdaspeed 3 Troubleshooting' started by Nicholas Sanchez, Aug 13, 2021.

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  1. Nicholas Sanchez

    Nicholas Sanchez Greenie N00B Member

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    PLEASE HELP ME. about 2 weeks ago i was driving around with my pops when suddenly my car had started misfiring bad. wasn’t doing no pulls or anything, just normal driving. I limped it back home and started diagnosing. swapped coil packs, nothing. swapped spark plugs nothing. (forgot to mention i had been getting a p2187 for system too lead at idle code about a week before this, randomly turned on one night while car was idling for about 15 minutes.) decided most likely injectors since i knew they were old and already leaking a little. swapped injectors and on first start it sounded bad but after a few seconds sounded normal, not misfiring at all. left to go on vacation the next day so i couldn’t put the car fully back together. came back 5 days later and assembled the car 100%. started it up and some thing misfiring on cylinders 2 and 3. everything was connected how it should be yet i was misfiring. i found a wire that was arcing on my intake clamp and had been rubbed through and severed around 4 strands of wire. put sauter on it and taped it up thinking that was the problem but nope. i’ve taken some logs going wot with this problem and noticed i’m running extremely lean on wot. i checked voltage running to injector wires and was getting about 12 volts. I’m out of ideas guys, i don’t know what this problem could be. hpfp is getting the correct amount of fuel and fuel psi looks good. i’m open to any ideas you guys can think of. compression and leak down test has been done, motor is healthy. please help me.

    it did have a p0202 and p0203 cel before i swapped injectors. now it just has a p0300. car idles somewhat fine but as soon as you start driving and give it little throttle it starts misfiring really bad.
     
    Last edited by a moderator: Aug 15, 2021
    Nicholas Sanchez, via an iPhone, Aug 13, 2021
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  2. jsilva

    jsilva Silver Member

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    Before rebuilding my engine my spark plugs decided to not spark. I had to run a wire from the grounding screw/plate near the hpfp directly to the negative battery terminal to get it to run. When I rebuilt my engine I spent a little time cleaning up the ground wire area, but then later had some occasional jerking and a CEL about the fuel pressure sensor. I replaced the sensor but eventually I had to spend more time sanding the ground wire tab and the plate to make them nice and clean and I used deoxit to help improve the connection. It has been fine since.

    It wouldn’t hurt for you to try that at least.
     
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  3. Nicholas Sanchez

    Nicholas Sanchez Greenie N00B Member

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    i just cleaned up that ground today, but i doubt that’ll be that since i’m getting good fuel pressure at the hpfp, just the 2 injectors don’t want to fire. thanks for the input though!
     
    Nicholas Sanchez, via an iPhone, Aug 14, 2021
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  4. Awafrican

    Awafrican Moderator Gold Member

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    make sure your injector pins arent bent... when I got mine back from cleaning they were not straight and I was getting one not firing because of shit contact, pulled harness off straightened pins and it started working.
    that ground that jsilva mentioned also grounds the injector harness so could be it too. check your harness for continuity sounds like you could have more of a harness issue too given the one that you fond. Also when fixing wires with solder you should be using heat shrink over top not just electrical tape
     
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