Idling Problems with my 306
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  1. #1
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    Default Idling Problems with my 306

    Hi, I have a 94 XR 306 with a 2litre 16v engine fitted. It was recently serviced including new fuel pump, timing belt, spark plugs, etc. The car is often idling incorrectly, sometimes revving up to 3000rpm when idling or stopped at traffic lights. You can actually cruise along at 50km/h without your foot on the accelerator. This is temporarily resolved by turning the ignition off and on again. Other times when you first start it, it will just cut out. It will do this a number of times until you can get the revs high enough.
    I have removed the idle stepper motor, cleaned it with throttle cleaner, and re-installed it. This has not resolved the problem. On occasions when going down long hills you can smell petrol like it is running too rich. There a a lot of black sediment in the exhaust pipes.
    On a longer trip the car runs fine.
    Has anyone got some ideas please?
    Thanks
    Lynden

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  2. #2
    Fellow Frogger!
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    I had a similar problem our 306 (1.8 8v).
    On our car the cause was a faulty coolant temperature sensor, which caused the car to run rich & with a very high idle.(intermittently.)
    Replacing the sensor, and also the fouled lambda (oxygen) sensor fixed it.
    Now the idle is perfect and fuel economy is superb (compared to before!)

    Yours could just be the lambda sensor. How many kms has you car done?

    Cheers
    spiz

  3. #3
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    Hi Spiz, the car has done 182k. The engine was replaced by the previous owner with the 2l 30k ago, but all he knew was that it was suppose to a low k engine.

  4. #4
    Fellow Frogger!
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    Check vacuum hoses for splits or loose connections.
    I would replace(with new items) the idle stepper motor & coolant sensor, and possibly the lambda sensor.
    Maybe try a new MAP sensor.
    [maybe before doing all of that to check that the timing belt has been put on properly, you never know.]

  5. #5
    1000+ Posts Andrew Ch's Avatar
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    Default Idling Problems with my 306

    As above check all intake hoses first. Regarding stalling issues when this happened to my daughters 306 it turned out to be the air hose going to throttle body. One of the pressed in plastic fittings had dislodged and was sucking in air. Reglued it in and no more problem.

    If this doesn't solve it try a new throttle position sensor as it controls the throttle from idle to throughout rev range.

    I believe it won't be lambda sensor unless your car is running very rich ( check plugs ) and your fuel economy is dreadful good luck.

  6. #6
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    Thanks. I will need to speak to the mechanic as they somehow squeezed the plastic cover back over the timing belt. It was previously not covered.

  7. #7
    1000+ Posts jo proffi's Avatar
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    Be carefull replacing parts that "might be the problem" until you are at your wits end and feel like some useless retail therapy.
    You'll feel like a mug if you replace all the electrical sensors and it turns out to be a dodgy accelerator cable.
    Get the car plugged into a diagnostic computer.
    This will show if the sensors mentioned above are within range (or if the accelerator cable is sticking).
    If they are not in range, it does not automatically mean you should rush out and buy a new part, as you should then check the wiring between the sensor and the ecu. Its common for plugs to get dirty or wires to have cracked insulation which leads to corosion.
    After all this is a french car we are talking about.
    A ridiculously high idle means too much air is getting into the inlet, so start with the obvious things like that the throttle plate is fully closing every time.
    I put an extra spring on my throttle as i like that system to have redundancy built in and the extra spring load counteracts my lead foot.

    Jo
    Last edited by jo proffi; 18th October 2012 at 03:48 PM.

  8. #8
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    Thanks Jo. That info is really helpful...

  9. #9
    Tadpole
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  10. #10
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    Thanks Luke.....

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