Stuttering Idle and Misfires on light throttle - Am I in trouble?
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Stuttering Idle and Misfires on light throttle - Am I in trouble?

This is a discussion on Stuttering Idle and Misfires on light throttle - Am I in trouble? within the Focus RS TroubleShooting forums, part of the Focus RS Garage category; Hi all, VIDEO: https://drive.google.com/open?id=1VG...bBRSLWlvZ7PU1m Sorry to be another worrying newbie but would really like some thoughts on the sound my car is making. MY RS ...

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Thread: Stuttering Idle and Misfires on light throttle - Am I in trouble?

  1. #1
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    Unhappy Stuttering Idle and Misfires on light throttle - Am I in trouble?

    Hi all,

    VIDEO: https://drive.google.com/open?id=1VG...bBRSLWlvZ7PU1m

    Sorry to be another worrying newbie but would really like some thoughts on the sound my car is making.

    MY RS is 2016 year and had the HG recall completed about 4-5k ago.

    Mods:

    Adam Tune+ 98 Tune w/ Cobb
    Scorpion cat back exhaust
    Sorption downpipe (sports cat)
    Mishimoto Intake
    GFB DV+ T9360 diverter valve
    Turbosmart wastegate
    Mishimoto Intercooler
    Airtec Intercooler piping
    Mountune Rear Engine Mount
    Radium catch cans and baffle plate
    NGK LTR7IX-11 (6510) 1-step colder Spark Plugs - Pre-gapped to TUNE+ Spec
    Mountune sound suppressor

    The video is of the car about 2 minutes after a cold start. I noticed this the last time I drove it and only started this time to record.

    If I lightly put my foot on the accelerator in neutral, the car will stutter faster and also record misfires. It appears to rev higher fine.

    The coolant level is fine and there is no white smoke, the video was taken at 9 degrees Celsius outside so there may have been a bit of moisture.

    Cobb has not thrown any error codes, no CEL on the dash.

    Any thoughts on what this might be? And what my next step should be?

    I am worrying it might be signs of the end...

    Thanks heaps!

    Nick

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    RS Member Northish's Avatar
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    Quote Originally Posted by NickChooka View Post
    If I lightly put my foot on the accelerator in neutral, the car will stutter faster and also record misfires. It appears to rev higher fine.
    I know this will sound unrelated but you might check your wiring around the rubber hoses for the valve cover Radium Catch Can. I have heard of an instance where the hose for that CC pressed some wires in that area up against the firewall, abraded them and caused them to short out. That then resulted in misfires. Low chance this is your problem, but also easy to check. Best of luck.

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    RS Pro lucky phil's Avatar
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    Quote Originally Posted by NickChooka View Post
    Hi all,

    VIDEO: https://drive.google.com/open?id=1VG...bBRSLWlvZ7PU1m

    Sorry to be another worrying newbie but would really like some thoughts on the sound my car is making.

    MY RS is 2016 year and had the HG recall completed about 4-5k ago.

    Mods:

    Adam Tune+ 98 Tune w/ Cobb
    Scorpion cat back exhaust
    Sorption downpipe (sports cat)
    Mishimoto Intake
    GFB DV+ T9360 diverter valve
    Turbosmart wastegate
    Mishimoto Intercooler
    Airtec Intercooler piping
    Mountune Rear Engine Mount
    Radium catch cans and baffle plate
    NGK LTR7IX-11 (6510) 1-step colder Spark Plugs - Pre-gapped to TUNE+ Spec
    Mountune sound suppressor

    The video is of the car about 2 minutes after a cold start. I noticed this the last time I drove it and only started this time to record.

    If I lightly put my foot on the accelerator in neutral, the car will stutter faster and also record misfires. It appears to rev higher fine.

    The coolant level is fine and there is no white smoke, the video was taken at 9 degrees Celsius outside so there may have been a bit of moisture.

    Cobb has not thrown any error codes, no CEL on the dash.

    Any thoughts on what this might be? And what my next step should be?

    I am worrying it might be signs of the end...

    Thanks heaps!

    Nick
    Whats the idle sound like and whats it drive like at full operating temp?

    Ciao
    If you're not living on the edge you're taking up too much space.

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    Quote Originally Posted by lucky phil View Post
    Whats the idle sound like and whats it drive like at full operating temp?

    Ciao
    The idle sound is what is heard in my linked video, I have not driven it long enough to get to operating temp with this issue but will have to at some point soon and can report back.

    The first time it happened, I started the car up and drove out my driveway, for about 5 minutes the car was misfiring pretty badly on acceleration and then calmed down.

    Not sure if that helps.

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    Quote Originally Posted by Northish View Post
    I know this will sound unrelated but you might check your wiring around the rubber hoses for the valve cover Radium Catch Can. I have heard of an instance where the hose for that CC pressed some wires in that area up against the firewall, abraded them and caused them to short out. That then resulted in misfires. Low chance this is your problem, but also easy to check. Best of luck.
    Thank heaps, I will check it out.

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    I have taken it to my mechanic and they took out my one step colder spark plugs and replaced with stock.

    The issue is still there but less apparent.

    They think it is either a custom tune issue or injecter no4 is not spraying correctly and needs to be replaced as it looked a bit black.

    It is at its worst on cold start and light acceleration but gets better after it warms up.

    Anyone heard any stories of injector issues?

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    Check your air intake for any leaks.
    Now after watching video, that to me sounds like big end bearing noise.

    Not good.
    I wish you luck with the repairs.
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    This is the idle sound after they changed the plugs.

    https://drive.google.com/open?id=1oD...xy6pKaD1jvsyV6

    They also performed a compression test and returned 125,125,115,118.

    Still think it could be bearings?

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    RS Veteran thirdgen89gta's Avatar
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    Why has no-one suggested returning the tune to stock and checking idle then.

    If the issue goes away, its the tune.

    If the issue remains, its not the tune and more than likely is something mechanical.

    You haven't done any modifications yet that would preclude you from running a stock tune safely.

    Mis-Fires are almost always related to fueling, timing, or damage in the cylinder.

    A failing bottom end (rod knock) doesn't show up as a mis-fire. The death rattle is instantly recognizable. This is rod knock without the soon to be present squeal.


    And this is a rod knock with squeak.
    NickChooka and insanekiwi like this.
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    Quote Originally Posted by thirdgen89gta View Post
    Why has no-one suggested returning the tune to stock and checking idle then.

    If the issue goes away, its the tune.

    If the issue remains, its not the tune and more than likely is something mechanical.

    You haven't done any modifications yet that would preclude you from running a stock tune safely.

    Mis-Fires are almost always related to fueling, timing, or damage in the cylinder.

    A failing bottom end (rod knock) doesn't show up as a mis-fire. The death rattle is instantly recognizable. This is rod knock without the soon to be present squeal.
    I didn't because of his WG, but I imagine that if he flashed the base tune and checked to see if he had misfire at idle that would eliminate the tune as a variable. Is that what you meant? I definitely wouldn't drive it in that configuration.

    OP, there were a few stories of injector damage from the HG repair. Are you getting misfires on one cylinder or random? If on one cylinder only, and you're mechanically inclined, consider swapping the injector. IIRC they're cheap enough that it might be worth your time.
    NickChooka likes this.
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