Misfire/Hesitation under slight load at highway cruising speeds

Discussion in 'Mazdaspeed 3 Troubleshooting' started by lenniejames, Aug 25, 2020.

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  1. lenniejames

    lenniejames Greenie Member

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    Hey there,

    I’m having a problem with my 2008 Speed 3. When I’m travelling along the highway with cruise control on and I go on a slight incline, the engine begins to burble/misfire after that slight load is introduced. It doesn’t seem to do it under full boost conditions. Only just at low rpms under medium load.

    Details on car
    148000kms
    Corksport Turbo Back Exhaust with Catalytic Converter Delete
    Cobb Access Port with Custom Stage 2 Stratified 91 octane Tune
    Cobb Intake
    Autotech Fuel Pump
    Cobb Motor Mount
    NGK ILTR6A-8G .032”
     
    lenniejames, via an iPhone, Aug 25, 2020
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  2. lenniejames

    lenniejames Greenie Member

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    Bump
     
    lenniejames, via an iPhone, Aug 26, 2020
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  3. Sleepy_Pat

    Sleepy_Pat Silver Member

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    From the looks of it, you have an ots tune of some sort. I would suggest getting a pro tune. If I’m wrong about that then start by closing up the gap on your spark plugs to .028 or desired gap from tuner.
     
    Sleepy_Pat, via an iPhone, Aug 26, 2020
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  4. Raider

    Raider Administraider Administrator Platinum Member

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    Plug gap is too big. clean MAF, logs to see if O2 Sensor is meh.
     
    Raider, via a mobile device, Aug 26, 2020
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  5. lenniejames

    lenniejames Greenie Member

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    Ok I will try new plugs with a smaller gap to start. And yes it’s an OTS stage 2 tune. Do you mean just cleaning the maf with some contact cleaner?
     
    lenniejames, via an iPhone, Aug 26, 2020
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  6. Awafrican

    Awafrican Moderator Gold Member

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    There's is a specific MAF cleaner, spray it into to the sensors (removed form car) you'll be able to the wires getting cleaner and let it dry out it back in.

    Your original post said stratified 91 octane tune and you made mention of the OTS stage 2 which one are you using? Or is it a stratified OTS tune? Reason folks are dialed into that is because Cobb maps are notoriously poop and can cause issues.

    also what do you consider "low rpm"?
     
    Awafrican, via a mobile device, Aug 26, 2020
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  7. lenniejames

    lenniejames Greenie Member

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    Okay I will get a specific map cleaner and pull it out and clean it.

    Sorry I’m new to the accessport and mazdaspeed 3 platform so I’m not really too sure. It has a couple of maps loaded onto the AP, and I think the one it says at the moment is Stratified OTS Stage 2 91 octane?

    around 2000-3000 rpm in 6 gear coasting along the highway
     
    Last edited by a moderator: Aug 26, 2020
    lenniejames, via an iPhone, Aug 26, 2020
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  8. Awafrican

    Awafrican Moderator Gold Member

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    okay so you're on the stratified OTS tune, not the cobb one thats good, Lex put some good effort into those and they run better than stock or cobb ones.

    I can tell you from personal experience that the cars don't like the load below 2500, but that shouldn't cause your issue. Hopefully with the MAF cleaned and fresh plugs appropriately gapped it resolves your issue. Like raider said take a data log of when it happens and post the CSV file so that it can get looked over.
     
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  9. lenniejames

    lenniejames Greenie Member

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    Oh okay cool. When I get to the car I will double check for sure. It doesn’t seem to do it straight away. Only after driving for about an hour or so. And once it starts it does it on the highway with the slightest bit of load as you go up a hill.

    I will also say that I live in the Canadian Rockies at an elevation of about 4200 ft. Would that causing my vehicle to run richer than usual? When it does start to misfire I will be sure to datalog and post.
     
    lenniejames, via an iPhone, Aug 26, 2020
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  10. lenniejames

    lenniejames Greenie Member

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    So I checked what tune it was and it says

    REV1 STRATIFIED 91 STG 2 FT MAZ V3.00
     
    lenniejames, via an iPhone, Aug 26, 2020
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  11. Easter Bunny

    Easter Bunny Professional Engineer Platinum Member

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    You don't need another set of plugs you can just regap the ones you have
     
    Easter Bunny, via a mobile device, Aug 26, 2020
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  12. lenniejames

    lenniejames Greenie Member

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    I just read from Cobb’s map notes that they reccommend the ITV22’s for when running more boost? Is that not necessary? How long between changes do these direct injection engines need before changing plugs?
     
    lenniejames, via an iPhone, Aug 27, 2020
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  13. Awafrican

    Awafrican Moderator Gold Member

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    Stage colder plugs start to be recommended when running more power. To my knowledge that's generally part of the tune, as in not just swapping heat ranges
    @Easter Bunny can set the record straight on that though.

    NGK >denso so their colder plugs would be NGK 6510. Personally I'd be more concerned about the stratified map notes matching it rather than Cobb's
     
    Awafrican, via a mobile device, Aug 27, 2020
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  14. lenniejames

    lenniejames Greenie Member

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    ahhh shoot, I’ve already ordered the Denso’s. Should I go back to one of the Cobb tunes preloaded onto the accessport when I install the new plugs?
     
    lenniejames, via an iPhone, Aug 27, 2020
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  15. Easter Bunny

    Easter Bunny Professional Engineer Platinum Member

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    Plug heat range should be based on the primary use of the car. If it is a DD then stock would be fine unless you had really stupid power.

    Weekend toy or primarily track use start running colder plugs

    If you have colder plugs in a DD they will run cold, duh, and foul more quickly


    I would never run any of the Cobb tunes
     
    Easter Bunny, via a mobile device, Aug 27, 2020
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  16. lenniejames

    lenniejames Greenie Member

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    So why is it that Cobb specifically recommends running a colder plug when increasing boost levels?

    What would you reccommend I do to try and get the car running right? It seems to only do it after a while of driving, not straight away. How long of an interval would you leave between changing plugs? These ones havent been changed I think for about 10000 miles or so. I’m not entirely sure though because I only just bought the car
     
    lenniejames, via an iPhone, Aug 27, 2020
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  17. Awafrican

    Awafrican Moderator Gold Member

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    Sorry I forgot the interval on plugs in my last post 20k miles is recommended for the speed the biggest thing is keeping that gap at .026-.028" that's where I'd start to get your car running better and a MAF clean, could clean your throttle body as well (another cleaner for that).

    As for Cobb I don't know their rational
     
    Awafrican, via a mobile device, Aug 27, 2020
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  18. Easter Bunny

    Easter Bunny Professional Engineer Platinum Member

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    I would check the gap on the plugs you have already and see if it helps. It's free to do so just do it. The plugs supposedly last 100 k miles. I have been changing mine at 50 k but honestly they look good when I pull them out. As long as the center electrode isn't worn down and the porcelain isn't cracked they are fine
     
    Easter Bunny, via a mobile device, Aug 27, 2020
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  19. lenniejames

    lenniejames Greenie Member

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    So I cleaned the MAF with actual MAF cleaner, and gapped the ITV22 plugs to .028” and so far so good. Haven’t seen any issues yet, but I’ve only driven it for about half hour or so since, and the problem was only occurring after 1 hour++ driving. So will report back after a longer drive
     
    lenniejames, via an iPhone, Aug 28, 2020
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  20. lenniejames

    lenniejames Greenie Member

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    Ok so I’ve had a chance to properly drive the car now, and the issue is still there. It’s still getting a hesitation/burbly misfire.

    any thoughts on what to try now?
     
    lenniejames, via an iPhone, Sep 4, 2020
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