Fluctuating / bad idle
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Thread: Fluctuating / bad idle

  1. #1
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    Default Fluctuating / bad idle

    Hello everybody. I am new in this forum. My name is Andy and I come from Germany. Since 2 years I am proud to be the owner of a MG ZT 260.
    Now i have a little problem.
    I took him out of the garage. He started normally first. When rolling down the hill I had 2 light hits, like backfire, in the exhaust. Then he rumbled as he accelerated. The engine was running totally rough at idle. The rpm fluctuated between 300 and 500 rpm until it went out completely. In terms of exhaust gases, it smells extremely like gasoline. As if he's not burning properly. After restarting, the engine speed did not exceed 2500 rpm, moreover it started to wobble and did not accelerate.
    I brought him to my trusted Garage. Fault code read out with T4 tester: P0113
    So far we have swapped the MAF sensor, IAC valve and cleaned the throttle budddy.
    After swapping these parts, it hast become a little better but did not solve the problem yet.
    Now he starts normaly and holds the idle rpm correctly. But after few minutes the idle starts to fluctuate again and a strange noise comes from the vicinity of the IAC valve. A short time later the idle is back to normal. Then the problem repeats.
    Big question mark!
    Maybe someone has another idea what to do?

  2. #2
    Registered User SCP440's Avatar
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    P0113 is high inlet temp. If you have a bad idle and are getting this code I wonder if the EGR is stuck open or partially open?

    Try blanking it off to see if the engine runs better. Just make up a metal plate and undo the two bolts that link it to inlet manifold.

    Steve

  3. #3
    #242 V8 on tour colintf's Avatar
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    Hi Andy and welcome.
    hope it's sorted soon. Whereabouts in Germany?
    colintf
    Colin Murrell
    vin 00242 - Probably the only 260 to have driven the full Le Mans circuit?
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    Thanks for the Tip Steve. We will have a look on the egr valve. I will give a feedback later.
    @ colintf : come from Hagen in Germany.

  5. #5
    #242 V8 on tour colintf's Avatar
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    Quote Originally Posted by AndyW View Post
    Thanks for the Tip Steve. We will have a look on the egr valve. I will give a feedback later.
    @ colintf : come from Hagen in Germany.
    That might help others with local knowledge help you Andy
    colintf
    Colin Murrell
    vin 00242 - Probably the only 260 to have driven the full Le Mans circuit?
    MG Car Club Z Register V8 ZT/ZTT Rep.
    MG Car Club V8 Register V8 ZT/ZTT Rep
    MG Car Club MGF Register Regional Rep for Devon & Cornwall and Cotswold Regions.
    MG Car Club MGF Register International Liaison Representative

    http://www.mgfim.org/

    http://www.two-sixties.com/main.htm

    http://www.v8register.net/

    http://www.mgfregister.org/

    http://www.racethemg.com/ http://www.triple-mracing.com/



    Member of MGCC (UK), MGOC, VSCC & TSSC (Triumph Sports Six Club)

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    Update: egr valve works perfect. But the problem ist still there.☹️

  7. #7
    Administrator Nich's Avatar
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    Quote Originally Posted by AndyW View Post
    Update: egr valve works perfect. But the problem ist still there.☹️
    Have you checked to make sure the fuel pump has not separated, it's under the rear seat squab on the right of the car looking from the front.

    Nich.
    Nicholas John Peter Tinker - # 484

    Manufactured on Tuesday 27th April 2004 @ 12.17.47.
    Commission Number: 24468.
    Brochure Model: M3 Tourer 4.6 V8 260PS.
    Specification Code: L01B.
    CICode: D1511.
    Trim Level: TL8.9 (M3).

    65th ZT-T 260SE to be made out of 115.
    11th ZT-T 260 SE in Pearl Black (PBT) out of 23 produced.

    Manufactured in the UK by MG Rover Group Ltd.


  8. #8
    Registered User SCP440's Avatar
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    If you can plug a code reader in with live data you should be able see what is going on. Fuel pressure, lambda outputs, IAC activity, EGR amongst others depending on the reader. Reading the information is very important, for example a lean mixture can be an air leak, a bad injector or low fuel pressure, miss firing plug or even a fault lambda sensor. A misfire will allow unburnt oxygen into the exhaust and the lambda will read this as a rich mixture so lean the mixture off.

    The fuel pressure on these engines does fluctuate as the pump speed controls the pressure rather than a pressure regulator. Low fuel pressure as Nich has said can be caused by the pump separating but also by a faulty sensor on the fuel rail or even the fuel pump controller it self.

    If the code is cleared does the same fault code come back?

    Steve

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    So new update.
    When the codes cleard, they did mit come back. Today i worked with the mechanic at the car. When we start it, there was the creepy noise again. When we took of the hose from the IAC Valve, we mentioned, that there sucked Air in but also Air comes out. It's like bubbling. Hard to describe.
    At first we thought that the catalyst were clogged. So we sepperated them from the exhaust mainfold. Same Problem.
    So we put everything together again.
    now we suspect a defective intake valve, because when the engine gets warmer, the noise comes directly.
    Tomorrow my mechanic want to unscrew the valve cover and do a pressure test.

  10. #10
    #829 called 'Olive' David's Avatar
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    The padded hose from the PCV valve on the left hand cam cover over to the throttle body plenum, maybe? Often the rubber elbows at each end can leak or become soft and collapse. The PCV valve itself should be replaced every 80k Miles.

    I can confirm the Motorcraft part numbers are:
    PCV valve: EV-261 (2C5Z-6A666-AA)
    Hose to Throttle-body: KCV-240 (2L2Z-6A664-FA)

    Unsure of MGR numbers, if thee are any.

    David

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