Swift CNG Cold Starting Problem

Problem many of us could face by installing a CNG kit on a car which has not been designed to work on CNG as per the car manufacturer. Avoid is what we will suggest. The cost of managing problems could work out to be more than the savings accrued from using a CNG over petrol. 

2006 model Swift VXi CNG fitted, the problem which I am facing with this that it takes too much time for getting started. I got service also but the problem is still the same.

Swift CNG Cold Starting Problem

Our assumption is that you are facing cold start problem (starting in the morning or starting the car after it has been standing for over 4 hours). This could be due to :

1) Car Battery older than 2 years. Such a batter has 'Cold Cranking Amperage' problem. Replace your battery with another test battery and check whether the problem is solved or not. If No

2) Get Injectors cleaned as continuous running on gas creates deposits in the fuel pipe If this has been done

3) Check fuel pump pressure. The pressure needs to be around 4.2 to 4.5 bar. If this is also done, then

4)Re calibrate the CNG - But this is only last resort. Ideally first 3 steps would solve your problem


Comment Posted Person Name Didn't require this toolbar? Click me I will put it asideHide Click me to view toolbar having option to comment, show existing comments etc.Show #View Number of Reply replyReply
Note:Please take a note of the icons, it will help you in faster communication with other users
  • After reading your comments of late starting, is it during the first start in the early morning or at every start you attempt.

    We should write it clearly to understand the symptom for eg:-

    1. Engine cranks normally but hard to start.

    2. Engine cannot be cranked while starting the vehicle, only the light in the odometer blinks.

    3. It takes a long time to start the vehicle in cold / warm start.

    4. Hard to start in the morning only.

    5. After running it is hard to start the vehicle.

    Causes of cold start problem are as follows:-

    For num.1, 3, 4 and 5

    a. Check the fuel filter for blockage, which traps the fuel in fuel filter and does not allows the fuel to flow.

    b. Check injector for open or short circuit which will not inject the fuel or allows excess fuel to be injected into the combustion chamber and not be able to ignites as we starts the vehicle.

    c. Check the CNG wiring for short/open which is attached to the injector’s coupler and check the CNG system which may be having a malfunction or needs to be calibrates.

    d. Check the spark plug and coil ignition.

    e. Due to the low compression an engine starts troubling in starting. Check the engine compression test for each cylinder, if it is below than what is given in the workshop manual the starting problem will occur due to the low compression.

    Causes of cold starting problem are:-

    For num.2

    • Check the output voltage of the battery by the multi-meter; it should not be below than 12.20 volt. If it is below, then charge the battery.

    • Check the self starter for bushes and brushes which might have worn out due to age. (The problems which mostly happen in all the symptoms are due to the overflow of the fuel or if fuel doesn’t pass through the system or it can be the CNG wiring or due to CNG system malfunction. And do check the valve clearance for proper timing also.)

    Anjan Surong reply