1st Gen R53 Cooper S Rough Idling @ Cold Start & Random Misfire Issues

Discussion in '1st Generation: 2002–06 R50, R53 & 2004–08 R52' started by minsanity, May 1, 2012.

  1. minsanity

    minsanity Well-Known Member

    Sep 11, 2009
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    Hi guys, need some advice. Trying to figure out what's causing this old reliable 02MCS to act up this past week. It's got 44k mi & lone K&N Typhoon CAI mod on it. Regularly serviced (every 5k)& well taken care of. Plugs, coil, wires,harmonic balancer are all stock & never changed yet though. Engine has never used up oil, never had to top it.
    These are the issues I've noticed:

    !. It starts instantly every morning but stumbles a coupla times before idle stabilizes as temp rises.
    2. Random DSC & SES PO300 fault code but car runs smooth upon reaching operating temp
    3. After car sits 5-10mins, it takes a coupla cranks longer to start w/ a slight stench of fuel=>rich. Always starts on 1st try though. Changed the coolant temp sensor on cylinder head, new belt, recharged the K&N CAI & cleaned the corroded #3 coil a coupla days ago, no improvement detected.:confused5: Changed both strut mounts too. Huge difference there!:Thumbsup:
    4. At operating temp, idle is stable @ 800. Random faint pop & burble can be sensed.

    Need your inputs on possible causes & where I should start.:idea:
    -Bad gas? Been running ethanol free premium gas. Might be a bad fill up? I'm trying to consume this tank & refill from another station next.
    -Signs of failing harmonic damper? Don't hear noises & visually, it still looks ok. Which is best? PRW or ATI?
    -vacuum leaks?
    -plugs, coil, wires?

    Hope to get it back to how it used to be. I'm crossing my fingers this is nothing serious. Maybe Khuevo could chime in? This forum has kept this mini in tip top shape all these years & I'm overly appreciative. Thanks, guys!
    Happy motorin' & more power!
     
  2. grodenglaive

    grodenglaive New Member

    Apr 3, 2010
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    Wow, that's low mileage for an '02. First off, I'd throw in a can of redline fuel system cleaner and give it the italian tune up. See if that helps, it often does.
     
  3. Jason Montague

    Jason Montague New Member
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    Jan 5, 2010
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    :cornut: P0300 = random/multiple cylinder misfire. Most likely: 1.plugs 2.ignition wires 3.coil 4.cylinder/valve carbon build up.
    Advice above is good advice. I would say: 1. change plugs 2. redline or SEAFOAM in the gas tank and through the intake(see our MA threads on Seafoam) at operating temp followed by Italian(spirited 30min highway acceleration and sustained speed) tune up.:Thumbsup:

    Jason
     
  4. k-huevo

    k-huevo Club Coordinator

    May 6, 2009
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    Because of the low mileage over a ten year period, I'm sure there is moisture accumulation in the fuel tank, and this could be part of the problem. Fueling after or during a station's storage fill could produce similar symptoms. Regardless, the first thing I would do is replace the spark plug wires with new OEM.

    A DSC code is a separate issue probably not connected to misfires.

    If you're not seeing a P1688, battery lamp, or overheating, then probably not the crankshaft vibration damper or belt. Idle is seldom affected with those failures. Although, if the belt has never been replaced I would change it due to possible oxidation, and try wiggling the damper while you're at it.
     
  5. minsanity

    minsanity Well-Known Member

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    Thanks for your replies, guys! I definitely welcome & would try all sound suggestions by elimination. Keep em comin'. Anyone tried similar symptoms? Kinda annoying at start up. Strange thing is cold start up turns engine instanly but gets a minute of rough idling, while when warm, engine turns after a bit of longer cranking but idles well. Hmmm. :confused5: Thought my coolant temp sensor was shot, hence the replacement. Off to trying advices....Thanks!
     
  6. minsanity

    minsanity Well-Known Member

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    Thanks for chiming right in K-huevo. Really admire the work you do! :Thumbsup:

    When Belt was replaced a coupla days ago, it still looked good, though thinner, of course. Have'nt seen 1688 & tried wiggling & turning the damper. Seemed good w/ no visible cracks. No overheating. Is PRW as good as ATI?

    1 habit of mine is to fill up when it isn't too hot out to get denser fuel. Dunno if that compunds more moisture into the tank. Would consuming this tank to maybe 1/4 level & refiiling from a different station be a logical approach? I'll definitely replace plugs. DSC lights up more often than SES when engine stumbles, but not everytime. Toggle can't switch it off. It turns off after every engine restart restart though. Any ideas on longer cranking issue when engine's warm?

    Aside from Seafoam & Redline, what other cleaner/booster brands would you recommend?

    Apologies for such a long post. Hoping to be enlightened. Thanks tons!
     
  7. Crashton

    Crashton Club Coordinator

    Jun 4, 2009
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    I've had very good luck with Techron over the years.
     
  8. k-huevo

    k-huevo Club Coordinator

    May 6, 2009
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    I use and recommend FP60.

    First replace the spark plug wires with new OEM, and provide an update afterward.
     
  9. BlimeyCabrio

    BlimeyCabrio Oscar Goldman of MINIs
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    May 4, 2009
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    Ditto Keith's spark plug wires recommendation. Numerous times over the past 112k miles, I've had weird misfire issues. It almost always comes down to wires or corroded terminals in my cases.
     
  10. k-huevo

    k-huevo Club Coordinator

    May 6, 2009
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    I experience this each year around this time when summer blends are introduced. You're using ethanol free fuel so this shouldn't apply.

    If you're not sure the ECU has the latest MINI program installed, I would look into an update.
     
  11. minsanity

    minsanity Well-Known Member

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    Will definitely heed your advices,guys! We'll see what works & will keep you posted. Never had to woory about lil quirks with my other cars (toyotas). But this 1 I love the most. Really appreciate y'all for helping out!
     
  12. Newbs49

    Newbs49 New Member

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    TECHRON
    The best there is!!!!!!!!!!!
     
  13. minsanity

    minsanity Well-Known Member

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    A quick update. Tried an old set of plug wires which definitely smoothed out the idle of the cold engine by @ least 70%. Upon 1st start up of the day, rpm was a bit rough for less than a minute but didn't stumble below 1k til it got warmer. Idle settled @ around +/- 750 upon reaching operating temp.
    Guess It's off to new wires & plugs + a fill up w/ injector cleaner/booster.
    Again, I'll still do this by elimination & see.
    Thanks for all your spot on ideas & help. Hoping to get this back healthy!
     
  14. Austinsynthetics

    Austinsynthetics Active Member
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    Mar 18, 2012
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    Other cleaners....

    Amsoil's Performance Improver works well too, see specifics using the attached link. MA members get 15% off displayed price using code MA201201 upon checkout from the site. P.i. Performance Improver Gasoline Additive - Austin Synthetics
     
  15. minsanity

    minsanity Well-Known Member

    Sep 11, 2009
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    Update:
    1. A freah tank of vPower seemed to eliminate warm engine start issues. A bad case of bad gas, I guess.
    2. Cold engine rough idle still came up, quickly turned off engine, cleaned old plug/wire terminals w/ some dielectric contact cleaner by wd40. Restarted engine. Whoa, SMOOTH! I'll have to stock em, wires & plugs then.

    Thanks y'all! I never doubted M/A, dint even post these issues elsewhere. A huge :Thumbsup: guys!
     
  16. turboguy327

    turboguy327 New Member

    Mar 17, 2012
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    Just a tip. The refueling when its not hot out isn't true at all. Fill up a gas can on a hot day and feel the temp of the gas. Its cold because the tanks are buried a few feet underground. Always the same temp. I ride a bike and can feel the ice cold fuel inside the tank on a hot day when I fuel up.
     

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