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Thread: Cold Start run-around

  
  1. #1
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    Stan Mulder's Avatar
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    Cold Start run-around

    Please advise what may be causing my Opel Astra’s (1996 1600ie) cold start problem. I have not had use of this car for three months after having the head refurbished at 330000km. The car has always started perfectly in all weather conditions but now the car won’t start until the ambient weather temperature rises. The old noisy starter was replaced by the agents a few months before the engine overall. The starting symptoms noticed are as follows:
    • The engine usually runs delicately a few seconds and then cuts out as if starved. If the throttle is pressed during the first few starts the engine immediately cuts-out. The ignition has to be repeatedly turned until it heats-up or else dislodging whatever’s stuck.
    • Eventually it starts running unevenly and then cuts-out or else backfires and stalls. The throttle now has to be held down to get the car idling erratically else it immediately cuts out. If you remove your foot off the throttle too soon it immediately cuts out as if starved of air or fuel.
    • Eventually after about 10minutes it starts running and can be driven and even restarted.
    • This only happens when the weather is cold otherwise the car starts beautifully.

    The history of the events surrounding the cold starting problem is as follows:
    • During the first test drive after the engine rebore a rocker arm broke (4th cylinder) and cracked the cylinder head, which had to be replaced by the machine shop not my mechanic.
    • The car was later handed-over to us with a warning, for some unknown reason, that a particular fuel injector maybe malfunctioning.
    • We could not start the car early the next morning but to our amazement, later on in the heat of the day, it started perfectly. The car was returned to the mechanic.
    • Tests showed the fuel injectors were working (injectors were also pressurized overnight). A relay switch was replaced and the mechanic returned the car claiming it was starting properly.
    • However the car would not start on cold mornings and nights, or when left parked in a cold parkade. Again we noticed that it always started immediately when the ambient air temperature got even slightly warmer.
    • The mechanic gave up and recommending an auto electrician.
    • This auto electrician replaced the thermostat and then did a successful diagnostics test. However on a cold day when they moved the car it again would not start and he recommended the car be taken to the manufactures garage who had dedicated diagnostic test facilities.
    • The agents identified a engine timing problem and found the 3rd (or 2nd) cylinder was not firing. They checked the timing cleaned various carbonized sensors and the car passed the models diagnostic test (tested on a warm day). The starting problem however persisted so they recommended that the cylinders firing problem gets rectified. The car was returned to the mechanic who insisted that the garage must not remove the head (to avoid costly repairs?).
    • The mechanic worked on the hydraulic thrusters and now claims that he has rectified the engines firing problem. Consequently he now sees no reason to remove the head to inspect the valves. He was practically counting his successful starts until on the first cold rainy day the car again would not start.
    • The mechanic claims he has since actually started the car on the following cold morning and consequently the starting problem is erratic and this proves the fault is electronic? However our usage of the car shows that the starting problem is predictable when it is cold and possible the temperature was sufficiently higher for it to start.

    Please assist,

    Thanks, Stan

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    LEE69's Avatar
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    CTS = coolant temperature sensor replace that and it should be ok.

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    I will check if my car has a CTS. Thanks Lee69 !

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    Stan

    Re: Old Post states

    "The coolant temperature sensor is relatively easy to check - it has high resistance when cold, and lower resistance when warm. Typically, they fail by going open circuit, and are high resistance all the time.

    If you backprobe the coolant temperature sensor wires and measure the voltage across the sensor while the engine warms up, you will see;

    initially something like 3 or 4 volts when the engine is really cold
    this will drop as the engine warms up
    at about 1 volt"

    This seems to mean that when the CTS fails you will have problems when the engine is hot not cold

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