Question 2nd Gen R56 Cooper S R56 S idle issues and running rich

Discussion in 'Tuning and Performance' started by wsdivall, May 27, 2018.

  1. wsdivall

    wsdivall Member

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    #1 wsdivall, May 27, 2018
    Last edited: May 27, 2018
    I have a 2007 R56 S w/ 64,000 miles on original motor. When I start the car (cold or hot), it begins to idle at 1K RPMs, but immediately starts to bounce between 1,000 and 1,500 RPMs (see video).

    My wife did borrow my car and filled it with regular gas instead of premium. The rough idle started about 30 miles after she filled up an empty tank with regular gas. I know regular gas has an effect, but didn't think it could be this drastic. I put a bottle of Chevron Techron in the tank when she got home.

    I drove it for about 10 more miles (on top of the 30 my wife drove) to get the check engine light to finally come on. I then took it to O'Reilly's and was given the following two codes. P129D (MAP Sensor) and P2096 (O2 Sensor). Which should I replace first, I'm hoping it's just one that is bad and that I don't have to replace both. Perhaps something else is wrong altogether, which is what brings me to you guys seeking help.

    I've also uploaded a picture of my spark plugs which were changed about 15,000 miles ago. Based on the dry, dark look, it appears I'm running very rich. Does the O2 Sensor replacement fix this?



    View attachment 42023
     

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  2. Dave.0

    Dave.0 Helix & RMW Powered
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    Have you ever had your car carbon blasted ? Walnut blasting the intake..... carbon build up on the back of the valves could also be the issue.
     
  3. wsdivall

    wsdivall Member

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    I have not. Good thought. I do only have 64,000 miles on the original engine.
     
  4. Dave.0

    Dave.0 Helix & RMW Powered
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    Yeah, that’s about the time to have it done.
     
  5. MCS02

    MCS02 Moderator
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    I am with Dave. I hear some people have to do it at around 40k. That plug looks like it came out of my old bike, actually they look worse!
     
  6. wsdivall

    wsdivall Member

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    PROBLEM SOLVED: I was digging around my motor looking for potential air leaks or broken plastic anywhere that might cause bad oxygen/fuel mixture, thus causing my O2 Sensor and MAP Sensor CELs. as I was doing this, I noticed the Solenoid connect was about to fall off completely. This is a cable that snaps in and I have no idea how it would have come loose like that during normal drive. I do recall back in October 2017 I had to replace my water pump and would have needed to disconnect that cable. I'm guessing I didn't seat it until it clicked tight.... and over time it wiggled itself loose. No idea, but we're back in action and idling smoothly. Thanks for any and all feedback.
     
  7. MCS02

    MCS02 Moderator
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    That’s great!
     
  8. 00Mini

    00Mini Well-Known Member

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    Gotta love easy and inexpensive fixes !!
     

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