Difficult starting -checking Crank & Cam sensors

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mro
mro Posts: 813 Forumite
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in Motoring
Car is difficult starting first thing or after a period.

Getting ECU fault codes for Crank & Cam sensors.


Once it has started, maybe warmed up, it is running ok.

Initially I had changed both Crank & Cam senors, car wouldn't start.


So went back to old Crank sensor, still with new Cam sensor (as not easy to change this one back).

So now car starts, but is difficult starting first thing or after period.


Any ideas on testing Crank & Cam sensors & diagnosing this ?

Thanks
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  • BeenThroughItAll
    BeenThroughItAll Posts: 5,018 Forumite
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    mro wrote: »
    Car is difficult starting first thing or after a period.

    Getting ECU fault codes for Crank & Cam sensors.


    Once it has started, maybe warmed up, it is running ok.

    Initially I had changed both Crank & Cam senors, car wouldn't start.


    So went back to old Crank sensor, still with new Cam sensor (as not easy to change this one back).

    So now car starts, but is difficult starting first thing or after period.


    Any ideas on testing Crank & Cam sensors & diagnosing this ?

    Thanks

    Do you own an oscilloscope?
  • arcon5
    arcon5 Posts: 14,099 Forumite
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    What was the actual error code and message
  • Alice_Holt
    Alice_Holt Posts: 5,949 Forumite
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    Could it be an old battery not spinning the starter motor to the necessary speed?

    Cold or Hot starting problems?
    Alice Holt Forest situated some 4 miles south of Farnham forms the most northerly gateway to the South Downs National Park.
  • mro
    mro Posts: 813 Forumite
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    BeenThroughItAll wrote: »
    Do you own an oscilloscope?
    No, just multimeter.
  • mro
    mro Posts: 813 Forumite
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    Alice_Holt wrote: »
    Could it be an old battery not spinning the starter motor to the necessary speed?

    Cold or Hot starting problems?
    That's what I thought, I knew in last few days my quite new battery, bought Dec 16, was getting iffy, wasn't holding charge or lasting when turning engine. Thought battery wasn't up to job, that its power/current was collapsing while turning engine. It is almost like the engine stops momentarily when cranking or misfires.

    So I changed/exchanged the battery yesterday, but still have problem starting first thing, starting when cold or after a period.
  • mro
    mro Posts: 813 Forumite
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    arcon5 wrote: »
    What was the actual error code and message
    19 Incorrect Revs per Minute (RPM) signal (crankshaft sensor) Incorrect signal, check sensor

    92 Camshaft sensor Incorrect signal
  • BeenThroughItAll
    BeenThroughItAll Posts: 5,018 Forumite
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    mro wrote: »
    No, just multimeter.

    In which case, unless your multimeter has a pulse width function or frequency measurement function (which few do unless very high end or designed for automotive use) you'll be restricted to testing that the sensor has a resistance within the expected range, and unable to test that it is actually generating a waveform while the engine is cranked.
  • EdGasketTheSecond
    EdGasketTheSecond Posts: 2,558 Forumite
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    Starting is most likely down to a deteriorated crank sensor. See if its resistance has gone higher than what it is supposed to be. Get a new one that actually works.
  • mro
    mro Posts: 813 Forumite
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    EdGasketTheSecond wrote: »
    Starting is most likely down to a deteriorated crank sensor. See if its resistance has gone higher than what it is supposed to be. Get a new one that actually works.
    At first I tried a new Crank sensor, but that did not seem to work, so I went back to my old Crank sensor, which was falling apart, wires shorting and I had to rewire.

    I returned the new Crank sensor to shop, which is being sent back to be checked and bought another one which I am trying, think 2nd one could be better, but not sure yet.


    I'm now wondering about compatibility issues and whether I need original Vauxhall sensors, as my car is 20+ years old from 1995.

    Problem is the new Crank & Cam sensors I bought were both showing in ECU fault codes, which does not bode well.
  • m_c
    m_c Posts: 79 Forumite
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    The fault codes could be symptoms and not faults, as some older Vauxhalls would show those faults whenever the engine was not running.


    Some vehicle detail would help.
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