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Punto feeling heavy...

Discussion in 'Technical' started by adigabnp, May 28, 2012.

  1. bhai

    bhai Esperto

    Messages:
    1,185
    Ahmednagar
    Grande Punto 1.3 90 HP
    Everytime I get readymade answer from Tata & Fiat that heavyness,powerloss,poor low end torque all performance related problems are due to only bad fuel quality.
    Even from Mr.Mangesh of fiat India.

    Friends I sold off my former 75 hp punto because of this problem. & now brand new 90 HP is also giving again such headache.

    fiat has tunned MJD to accept bad quality Indian diesel. I bet that if we run original Italian MJD engine on Indian fuel it will fire dozons of ECU errors.
  2. gurjinder

    gurjinder Staff Member Janitor

    Messages:
    3,989
    Punjab
    Bhai sahab, i'm sure you will face loss of power issue in 2 litre 165bhp Punto as well. I think you have extreme driving skills like Michael Schumacher. Every car feels underpowered to you.

    Cheers.
  3. bhai

    bhai Esperto

    Messages:
    1,185
    Ahmednagar
    Grande Punto 1.3 90 HP
    It seems that all members have right to write about power loss,heaviness issue etc.
    But when my turn comes suddenly some people start objection

    If somebody feels that Mr.Bhai is wrong then neglect it.
    Why objection & indirect critics?

    I never wrote these type of indirect critics on any member even a member is arguing any wrong statement. Then why one should do act like this with me?

    Whenever I wrote problem of power loss,intention is only to disclose what type of ASS I am getting from Tata. I am not bashing fiat.
    4 people like this.
  4. Srini

    Srini Regolare

    Messages:
    468
    Chennai
    Agreed with Bhai!!
  5. Interesting topic!
    Well if you compare the actual figures, the weight difference between the Swift and Punto is hardly 40-50 Kgs. which honestly is negligible. The most common problem that people seem to be reporting is the lack of pick up in 2nd and 3rd gear. Its more prominent with the AC switched on. Immediate culprits that come to my mind are, ECU tune, gear ratios, ambient temperatures, bad fuel and so on. If the gearing is taller, the acceleration would be slower but you will be able to achieve higher top speeds. Swift has shorter gearing and that's why feels very peppy upto 100-120 Kmph but struggles from there on, a clear indication of a shorter Final Drive ratio.ECU tuning could also be responsible.
    During summers, the ambient temperatures are higher and as we all know, hotter air is thinner or has lesser density. With the reduction is density, there is lesser oxygen available for combustion. In my opinion this is the precise reason why there is an intercooler in the first place. The exhaust gases just drive the turbine wheel but since the exhaust gases are extremely hot, they heat up the entire turbo assembly and since the turbine wheel is connected to the compressor wheel, the incoming air also gets heated which is cooled in the intercooler.
    The intercooler cannot drop the air temperature below the ambient air temperature.So based on the MAF, IAT & O2/Lambda sensor readings, the ECU varies the fueling to maintain the ideal AFR. So theoretically I think, if the intake air temperature is more,meaning lesser oxygen, the O2 sensor will read that and report it to the ECU. The fueling would be adjusted with respect to the O2 reading since the AFR has to be maintained since we dont want unburnt fuel.Therefore, reduced fueling will reduce power which I guess would be noticeable ?
    If any of you have observed, in winters, almost each and every car performs better.
    Quality of fuel also affects performance because as soon there is bad fuel, the knock sensor with pick it up and the ECU again would intervene and adjust tuning values like fueling and ignition timing to avoid knocking, again resulting in reduced power.

    One more thing I would like to add, when you replace the air filter, in my opinion the ECU must be reset by disconnecting the -ve battery terminal for 1-2 minutes. This is something very simple and can be done at home, there is no harm in trying right ?
    What if the TASS guys forgot to do it ?
    Another thing worth mentioning, at 60k Kms, I had got the injectors of my swift cleaned from an Authorised Bosch Service Centre which had the facility to service Common Rail injectors. It was expensive,cost me 5-6k or so but trust me it was worth it!
    The car literally started flying, just like she was new. Remained like that for another 30-40k kms when I finally sold after that at around 90k Kms.
  6. RaviHegde

    RaviHegde Regolare

    Messages:
    299
    Karnataka
    14.62°N 74.85°E
    Grande Punto 1.4
    Agreed - air is thinner in summer because of higher temperature. Will it be so thin that engines struggle? I am not sure. If that is the case humans also should be gasping in summer. But I don't see that happening. I feel engines are much more resistant to breathing problems than humans. In peak traffic humans struggle to breathe because of engine exhaust fumes. But no engine struggles - engines are happy producing so much exhaust to choke humans :)

    My guess is - Engine components are precision engineered. During summer metal expands increasing the gaps inside the components. It can cause issues in components like fuel pump to pump at lower pressure. It can cause similar problems with multiple components to bring down the overall engine power. Another related problem is fuel. Fuel density varies quite a bit with temperature variation. Thinner fuel may cause the engine to "get less to burn". Therefore engines may perform poorly in summer heat.
  7. bhai

    bhai Esperto

    Messages:
    1,185
    Ahmednagar
    Grande Punto 1.3 90 HP
    Intake air temperature plays an important role in performance.

    Just before 15 days pre-mansoon shower happened in my district.

    All atmosphere was cool. Temperature came down to 22 degree.
    I noticed that car started to give better performance. But on next day again temperature rised to 40 degree. Again performance dropped.

    I could not judge wheather it is due to ambient temp. or due to good quality fuel.
    To check it again I visited that specific bunk. But due to technicle fault I could not refill on that bunk. So I visited another bunk. But on that day temp. was 40 degree.

    @ mods - Again humble request
    Please do not misuse power of post deletion.
    Even I compared MJD with another engine,sell of MJD will not decrease.
    Last edited: Jun 4, 2012
  8. gurjinder

    gurjinder Staff Member Janitor

    Messages:
    3,989
    Punjab
    Guys, a turbocharged engine( e.g. Multijet and Tjet) will only feel a negligible impact on it's performance due to thin air. That's applicable when you take the car high up to the mountains.

    On a hot, very hot summer day, there will be no perceptible impact on performance. I can attest to this fact.

    Cheers
  9. jumu

    jumu Superiore

    Messages:
    969
    Chennai

    Gurjinder, I wish to disagree. There is a difference. Why shouldnt there be a difference?. Every change in input parameters does will show up in the output, especially for a person who has a passion for the subject and is discerning. A normal person will not find the difference as he may not even think on the subject. @Bhai may be having a point.

    A drop in temperature and heaviness in the air is loved by diesel engines as the mass of the intake air increases, the compression is better. You can see a drop in fuel efficiency in summer due to thinner air as well as the overtime working of the air conditioner and its struggle to attain grill temperatures faster. The reverse of this works in winter. This is my third summer in the Punto and its been like this all along.

    I am not an engineer but experience and observation with passion does compensate for lack of qualification on paper.:)

    Cheers

    Abdul
  10. gurjinder

    gurjinder Staff Member Janitor

    Messages:
    3,989
    Punjab
    Rather than a normal person, in a normal driving situation no one can find any difference. I am regularly driving in 45+ degrees (afternoons) and i'm yet to find any difference. It feels the same as it did in the winters during 7-8 degrees.

    In normal driving situations, you will be hard pressed to tell whether hot weather has caused any deterioration in performance. The margin is that slim in a turbocharged engine.

    But to think it can cause a day and night difference is pretty much wrong.

    Cheers.

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