Rough idle, stuttering cold start, p0300

Discussion in 'Mazdaspeed 3 Troubleshooting' started by Alden, May 3, 2020.

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  1. Alden

    Alden Greenie Member

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    I've tried cleaning the MAF many times, but I doesnt really help. I do monitor the coolant temps, but I've never really monitored them to see if they match ambient temps pre start up. I can tell you, they seem to be behaving regularly with driving conditions. It's not even that the car runs rough during idle anymore, maybe a bit? It's just the coldstart random misfire thats really bad.
     
  2. Alden

    Alden Greenie Member

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    Anyone see anything in these start up logs? Still trying to solve this random misfire on cold start... and a small evap leak, and gross evap leak.
     
  3. SyntheticAtmosphere

    SyntheticAtmosphere You only get ONE ride, ONE ticket, ONE time! Silver Member

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    If you have an evap leak, I would chase those down asap. Not too hard to check, use a smoke machine or a vaping friend to find line leaks. Could also be an issue at the charcoal canister, gas cap or filler piping too. The evap system applies vac and pressurized events, as well as potentially adding vapors to the intake track at various times. If the computer is not seeing things happen at the right time is gets a bit confused sometimes.
    What codes are you getting? Have you had them all along?
     
  4. Alden

    Alden Greenie Member

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    I have checked the purge valve, which was functioning correctly, i haven't checked anything with a smoke machine yet. The codes are a small evap leak, and gross evap leak, but i cant remember the actual codes.. i wanna say P0455 and P0456. I've had the small leak come and go for maybe a couple years, gross evap leak showed up just recently. I do plan to get these dealt with, I'm just more concerned with the random misfire on cold start, as thats been an ongoing issue for like 4 years now.
     
  5. SyntheticAtmosphere

    SyntheticAtmosphere You only get ONE ride, ONE ticket, ONE time! Silver Member

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    P0455 and P0456 are essentially the same code, just different level of severity. Basically the car is not able to pressurize or apply vacuum to the fuel tank/evap system during self test shortly after startup. Could also be a small leak had now become a bigger one too.
    As for your logs, I didnt see anything...However I am not the guy for that unless its pretty obvious in the numbers.
    Any more white powder/water residue of the coils/plugs? I am wondering if water was possibly getting in through the hood scoop. I figured mine happened while cleaning the engine bay.
    Are you still checking your plugs at all? What do the electrode ends look like?
     
  6. Alden

    Alden Greenie Member

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    Yea i'll do a smoke test on it once I take it out of storage next year. I haven't checked the plugs since changing them last, so I'm not sure! Im tempted to buy a new set of injectors and CS seals and seeing if that solves my coldstart misfire...but that gets expensive quick lol so we'll see. I did buy a used set of injectors and made sure they were spraying properly before putting them in, and put in new OEM seals... but it didn't help at all. Might sell the car next year, at my wits end trying to figure it out!

    If anyone can look over the logs, it would be appreciated!
     
  7. SyntheticAtmosphere

    SyntheticAtmosphere You only get ONE ride, ONE ticket, ONE time! Silver Member

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    FYI...
    Cheapest CS seals I have found north of the border is from OSSmotorsport $286cdn (free shipping over $250cdn). Add $57cdn to include the injector puller tool.
    Started a thread <here> about Injector cleaning in Canada.
     
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  8. GobSpeed3

    GobSpeed3 Greenie N00B Member

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    Hello I came across this thread and decided to give my input which could or won’t help, but the sputters cold start could also be caused by your shutter valve, I doubt it’s the reason because you haven’t mentioned any codes like p2009 or p2004/p2006. but my shutter valves once were stuck open, and they aren’t suppose to open until the car is warmed up, and during cold start if they’re stuck open it causes the sputter, reason I don’t know maybe too much air going in and it’s messing with the cold start, but that’s another possibility, highly doubt it
     
    GobSpeed3, via an iPhone, Jan 25, 2023
    #48
  9. hexwrecker777

    hexwrecker777 Greenie N00B Member

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    So I've been experiencing this rough idle issue ever since the weather began to cool down here in CA. My 2012 speed3 with stage 2 bolt ons has been throwing the p2006 code for a while, but never resulted in this goofy idle. Now it throws the p2006 code and the p0300 code, even though I've cleaned my MAF sensor, replaced spark plugs, and ignition coils. My shutter valve isn't properly mounted however and I had to custom fab a piece of aluminum to get it sitting on the actuator again. Do they sell oem mounts for the valve?
     
  10. Alden

    Alden Greenie Member

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    Hey guys,
    Unfortunately I'm stuck driving my Speed during the winter months this year and noticed that my cold start issue goes away once the ambient temp gets around 0*C. I notice as it gets colder outside, the RPMs dont seem to jump as high during cold starts, but the misfire is completely gone all winter so far, aside from one warm day we had and it had a rough cold start, but nothing like during the summer months. Any ideas what could be causing this issue to improve with colder ambient temps?
     
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