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Thread: Ignition timing

  
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    Ignition timing

    I was just wondering - is this right :

    with a cold engine the ecu advances ignition timing and keeps the injectors on longer (riching up the mixture) this is the old equivalent of a choke.

    the reason I ask is that LPG needs an advanced ignition timing as it burns slower - which would explain why the car runs better when cold.

    or is this just a load of old cack?

    secondly - is there a way to fool the cars ecu into thinking that the ignition has been advanced? eg. the engine is always cold?
    It is only when the last tree is felled, the last animal killed and the last fish hauled from the sea that we will realise we can't eat money.

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    no taker's

    i'lk try help you.

    the ignition timing is controled by the ECU it get's the timeing info to fire a spark from the camshaft and the crankshaft sensors.

    the mixture is controled by the engine temp sensor. air intake temp sensor. and mass airflow meter. and lambada sensor in the manifold

    both are cleverly controled by that ECU.

    as for makeing the engine cold you cant realy because it;s allway adjusting the mixture to it's conditions.


    to make it over feul' (run rich)

    you could TRY dissconecting the mass air flow meter connector.

    then when it's not sending a signal back to ECU it will try compensate by over fueling. but then this will nacker up the 02 sensor . thats if the 02 hasnt already tryed adjusted the mixture by sending signals to the ecu.


    hope it helps ya
    astra g 1.8 sri 5dr star silver

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    Unhappy

    thanks for replying Mark.

    I'm thinking along these lines - put a resister in between the coolant temperature sensor and the ecu - this will make the ecu think that engine is cold (when it really isnt). The ignition timing will be advanced (which is what I want) and the injector will squirt more fuel in (which it won't as the LPG system disconnects it).

    This the same as those ebay mod chip jobbies. Is there likely to be any other issues I'm missing here? If all else fails I can just take out the resistor.

    Do you know where the coolant temperature sensor for the ecu is located on this engine?

    Ta - oh noticed fue prices going up again today - joy
    It is only when the last tree is felled, the last animal killed and the last fish hauled from the sea that we will realise we can't eat money.

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    the coolant temperature sensor will be down by the thermostat housing (somewere) there will be two sensors 1 for the gauge on the dash the other for the ecu.

    try dissconnecting the multi plug on the coolant temperature sensor first then if engine stays in warm up mode you no it will work.


    if it does work then you fit a resistor. dont no witch wire you'l fit the resistor too there will probably be two on the sensor.
    the car will probably stay idleing and 1500rpm.
    astra g 1.8 sri 5dr star silver

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    You mention LPG, is your car infact fitted with LPG ?
    The ecm is not as stupid as people think, if you disconnect a sensor like the CTS it is going to go into LOS, and give a rough fuelling equivalent ot a HOT engine, this is pretty much standard pratice for all ecm's.
    Lamda sensor values are often ignored when it recieves a COLD CTS signal, and it reverts to state map fuelling.
    Mixture is controlled pretty much entirely by CTS as this is the main corrective factor, others such as LOAD by either MAP or AFM add/subtract from base map, air temp is a tiny trim on this.
    Disconnecting the MAF or MAP will result normally in LOS situation, no power bad running as it substitutes SAFE values of a warm engine as a protection.
    Why are you farting around with resistors and crap like that, and looking to do things with an ecm that you do not understand the functions and workings of.
    Why not install A SPARK ADVANCE UNIT , such as WOLF 3N ?
    This is what it was designed for, will do all you want and NOT interfere with in any way the petrol running.
    I ran 58 degrees total advance on my xr4i on gas, plus "overfuel" for another 25bhp.
    If you are set on killing your car just use a RESISTANCE WHEEL on CTS, but I can absolutely gaurantee you it will not work.
    tabetha

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    Of course my car runs on LPG - why would I want to advance the ignition if it just ran on petrol?

    99% of the time I run on LPG. The LPG has its own ECU to control LPG mixture - tick over speed - amount of fuel for a given engine load etc - it makes these adjustments for the O2 sensor and throttle position sensor. It does however rely upon the cars ecu for setting the ignition timing - so if I can make the ecu advance the ignition timing for the price of a resistor then I'm game for that.

    The cars igniton is set to run on petrol not lpg so the ignition needs tweaking slightly.

    I'll do some googling on a spark advance unit.

    'Farting around' as you put it is how people learn.
    It is only when the last tree is felled, the last animal killed and the last fish hauled from the sea that we will realise we can't eat money.

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    Quote Originally Posted by clanless View Post
    the reason I ask is that LPG needs an advanced ignition timing as it burns slower - which would explain why the car runs better when cold.


    do you meen it runs better in the cold on lpg
    astra g 1.8 sri 5dr star silver

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    yes - it does run a little better when cold with the ignition slightly advanced. When hot during acceleration - the engine seems to 'miss a beat' occassionally- which it does not do when cold. Motorway driving (constant speed is not a problem) - which is handy as this is the majority of my mileage. I'm going to ask a mate of mine who works in electronics to work out an appropriate resister value and see how it goes.
    It is only when the last tree is felled, the last animal killed and the last fish hauled from the sea that we will realise we can't eat money.

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    wouldent it be better to get one ov those EBAY resistor things for the 'air intake temp sensor'

    so the engine will think it's cold air comeing in so it will rich it up.

    could be just what you need
    astra g 1.8 sri 5dr star silver

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    I did think of that initially - but I did a search of this forum and apparently the 1.6 8v doesnt have an air temperature sensor - its too old a design. Good suggestion though.
    It is only when the last tree is felled, the last animal killed and the last fish hauled from the sea that we will realise we can't eat money.

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