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    Update Archived Message

    Posted by Ian Staples on March 18, 2008, 10:11 pm, in reply to "Vauxhall Astra-F 1993 1.6L C16SE auto"

    Right, had the car for a week while customer went on holiday. At the begining of the week i had a sudden idea, check the amount the IAC valve moves.

    Under test the ECU only moves the valve through about 5mm (between 16mm and 21mm, those measurements will vary depending on where you reference the measurements from, but the constant is 5mm range), yet the thread is about 5 times that, i also noticed when the engine was running that the ECU was always commanding a setting of 149 which is fully-in which would pull the taper away from the air hole which would be right because its trying to increase the idle as it wouldnt tick over. When you switch off the ignition the ECU resets the IAC valve to 149 (fully in, or full idle speed) ready for the next start. I reset the start position to 13mm by screwing the shaft in, it then moved between 13mm and 18mm. started engine and idle speed started at 1500rpm with idle command of 149 then came down to 800rpm with idle command of about 113.

    I started the vehicle every morning and every evening after that for the rest of the week, with no problems what so ever.

    The customer has been driving it for 4 days now and not complained, i'll speak to her in a few days.

    Hope i explained that good enough, if not then reply and i'll explain better.

    Hopefully this is the fix!!! A couple of weeks driving will tell.

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