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What to check when car is under performing

Discussion in 'Engine Compartment' started by Sat-Chit-ananda, Apr 16, 2013.

  1. Under performance is hot topic these days.I just wanted write down few guidelines that might help to resolution.

    1) Car is taking time to climb RPMs and FE is low

    Possible issues could be Adulterated Fuel,in MJD turbo or turbo hoses/clamps can be culprit.

    2) Rough engine note and FE is low

    Possible issue could be clogged EGR valve,Manifold and may be oil inside intercooler.

    3) Low end torque is fine but mid range and top end is suffering

    Very well #2 could be an issue but also Airfilter MAF sensor or MAP sensor may need cleaning

    4) FE and performence is fine but NVH levels are high and harshness is felt.

    Oil and Oil filter needs to be checked and might need a replacement,NVH levels tend to go down with a high quality Synthetic oil.

    Please feel free to add your inputs
    12 people like this.
  2. bhai

    bhai Esperto

    Messages:
    1,181
    Ahmednagar
    Grande Punto 1.3 90 HP
    If examiner is showing ' All is well' then only one issue.

    Bad fuel!
  3. DRIV3R

    DRIV3R Esperto

    Re: What to check when car is under performening

    That is not true. How do you expect the examiner to detect mechanical aspects like a punctured turbo hose/loosely held clamp, etc.?

    Many scenarios like these do not register an error code.

    This is what I hate from the ASS guys whenever they troubleshoot, they just hook up the scanner and say all is well. They also go to the extent of saying that everything is fine until u get the CEL on. Not done!

    Sent from my GT-I9100 using Tapatalk 2
  4. theblack

    theblack Esperto

    Messages:
    2,188
    Bangalore
    This could also be a case as simple as Air intake pipe gone loose from its engine holder.

    Check Diesel filter and replace if needed
  5. Surya

    Surya Superiore

    Messages:
    930
    Namma Bengaluru
    Following things are vital for the proper and efficient working of a engine :
    1. Fuel - Quality of the fuel should be good for better performance.
    2. Air - As we know air (oxygen) plays an important role to generate enough power, hence the Air intake which flows through the air filter through turbo directly into the cylinder plays key role in performance.
    3. Oil (Lubrication) - The lubrication system makes sure that every thing moving inside moves easily and effectively.
    4. Exhaust - An Exhaust system is equally important as others as it has to pull out the exhaust gases from the cylinders if air resistance makes it hard for gases to exit a cylinder, then it robs the engine of power.
    5. Electricals - The Battery plays a important role in the car as its powering the entire system including the engine.
  6. naveen2cool

    naveen2cool Superiore

    Messages:
    646
    Chennai
    My car under performs when the external temperature is very hot, that is during mid day :(
    Guess it is the AC which keeps working all the time.
  7. theblack

    theblack Esperto

    Messages:
    2,188
    Bangalore
    This is expected because hot air is less dense which means there is less oxygen to burn inside your engine.
    AC does reduce the performance by a bit but not so steep that it is a nightmare to drive
    3 people like this.
  8. Surya

    Surya Superiore

    Messages:
    930
    Namma Bengaluru
    Drive a conventional tin box to experience the nightmare..:evilsmile
    1 person likes this.
  9. Linear

    Linear Amatore

    Messages:
    236
    Thane
    It's not due to the AC. It'sbecause the engine is sucking in hot air which has less density & as such provides lesser oxygen for burning.
    2 people like this.
  10. naveen2cool

    naveen2cool Superiore

    Messages:
    646
    Chennai
    That is why I prefer night during my driving holidays :)

    Wish I could set up a oxygen cylinder and connect it to air intake :evilsmile

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