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cold starting

Discussion in 'Classic Audi Forum' started by imported_delboy123, Jul 14, 2004.

  1. imported_delboy123
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    imported_delboy123 Guest

    [Jul 14, 2004]
    Please help me, i have a audi 80 1.8 1990, all of a sudden it is having trouble starting from cold, i removed the cold start valve and couldnt get any petrol through when cranking, i have now tried 3 cold start valves all be it from breakers but still no joy surley they all cant be faulty,, i read some where it may be the thermo-time switch but cant find it anywhere and dont know what it looks like as there is no picture in the mannual,,, please help thanks vince
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  3. audi5e
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    audi5e Member

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    [Jul 15, 2004]
    Vince, on my 100, the cold start valve is controlled by the ecu, this gets a reading from the temperature sensor switch on the water outlet going to the top of the radiator. if that sensor goes then it will obviously not get a reading. I am not sure if the 1.8 80 also uses this method?
    also it may be worth while to check if you get a reading from the wiring that plugs into the cold start valve. this will give different readings when the engine is hot to when it is cold. not sure if this will help?
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  4. imported_delboy123
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    imported_delboy123 Guest

    [Jul 16, 2004]
    Thanks a lot for your reply mate,im grabbing at straws here aint got a clue what in doing or what to check. my manual says the cold start valve is controled by the thermotime switch, but does it show you a picture?? does it buggery...
    could someone please tell me in very simple terms what tests i can do to find what the fault is....PLEASE...
    RIGHT........
    WHEN THE ENGINE IS COLD I TOOK THE COLD START VALVE OUT, BUT LEFT THE ELECTRICAL PLUG AND BRAIDED FUEL LINE CONNECTED, CRANKED THE ENGINE AND NOTHING COMES OUT OF THE COLD START VALVE.
    WHEN IM TRYING TO START THE CAR I HAVE TO CRANK IT FOR ABOUT 20 TO 30 SECONDS THEN IT CATCHES AND TICKS OVER VERY VERY SLOW,IF I TOUCH THE ACCELERATOR WHILE ITS TICKING OVER SLOW IT JUST CUTS OUT,, BUT IF LEFT TICKING OVER SLOW FOR ABOUT ABOUT 10 SECONDS IT GETS FASTER AND FASTER UNTILL ITS TICKING OVER NORMAL.

    THERE I THINK I HAVE TOLD YOU ALL I KNOW,, PLEASE HELP I CANT AFFORD AUDI DIAGNOSTIC PRICES
    SORRY ABOUT THE CAPITAL LETTERS..... CHEERS VINCE
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  5. imported_delboy123
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    imported_delboy123 Guest

    [Jul 16, 2004]
    Hi again I really do appreciate you trying to help me, if Im not answering your questions very well , its not because im being rude im just a bit thick /ubbthreads/images/graemlins/confused.gif

    As for what injection system it has? i m not sure so im attaching a picture and hope you can tell from that,,,,, well thats stuffed that up i can see how to upload a picture, it asks for a URL. I said i was thick /ubbthreads/images/graemlins/grin.gif oh i found it( see attachment /ubbthreads/images/graemlins/grin.gif
    anyway a bit of a update;; with the engine cold i connected a test lamp to one of the terminals of the connector that plugs into the cold start valve cranked the engine and the bulb lit all the time the engine was cranking over. which i guess meand its getting power? when i stop cranking the light goes out.
    i connected it to the other terminal and nothing /ubbthreads/images/graemlins/confused.gif
    i then warmed the engine up thinking the bulb wouldnt light but it did the same as when the engine was cold /ubbthreads/images/graemlins/confused.gif
    i cant see anything on the back of my cylinder block but have a number of things that look like the picture in the link you gave me either on the block or going in to water pipes (4 in total)
    with the bulb lighting saying power to the cold start valve, could i really have tried 3 dodgy ones?? wouldnt it be nice if i could connect my start valve to someone elses audi.
    sorry for rambling.
    thank you very much for your help vince
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  6. audi5e
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    [Jul 18, 2004]
    Hi Vince, ok, had a look at your picture, it looks just like a KE Motronic system. The 2litre AAD engine also uses that injection system (is yours not the AAD?, the engine code should be on the block on the right hand side). From the info you have given me, I would say that the temp switch is at fault, which is giving a wrong reading to the Electronic Control Unit (ECU). The ECU is in turn sending the wrong signal to the cold start valve. I think that the voltage would be off or reversed when cold. this would open the valve. if the temp sensor is giving the wrong info then the ecu would keep the cold start valve closed. hence no fuel. ok, enough waffling on from me... :)

    according to my haynes manual, the temp sensor for the injection system is on the coolant outlet union on the left hand side rear of the cylinder head. if you have two sensors then the inner one is for the injection system and the outer for the temperature gauge on your dash.

    maybe try changing that sensor and see if it helps.

    according to the manual the sensor is a thermistor which has a set voltage supplied from the ecu, the change in temp changes the current and so lets the ecu know what the engine temp is. this sensor controls how the ecu handles all injection processes. if this is faulty then the ecu sitches to a "backup program", you car will still run but not as efficiently as when the sensor is working.

    ok, that is my brain fried from too much thinking and typing... :)

    I hope this helps! (Gordon)
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  7. audi5e
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    [Jul 18, 2004]
    don't worry you are not being rude. more likely my south africanisms are probably coming through and make my text look a bit blunt....
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