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Thread: Frequency of knocking in 11th Gen Corolla

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    Default Frequency of knocking in 11th Gen Corolla

    Greetings Pakwheelers,

    I have a 2015 Corolla xli, maintained by Toyota Gujranwala with a mileage of 10k. Car is mostly city driven so I have to change gears a lot. Now sometimes when I shift from 1st to 2nd gear, I'll hear knocking in the engine for a split second before disappearing, especially with ac on. I shift into 2nd gear with an rpm that is usually +1k. I use a mixture of normal to high octane petrol in 80:20 ratio.

    To all other owners, is this behavior normal? Can it be eliminated/minimized? Do I need to rev match and get the rpm to +2k before letting go of clutch? What are your experiences/suggestions?

    Ps. Anybody know which pump sells good petrol in sialkot, do tell

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    Its normal just ignore it, mix hi octane from time to time
    RIP

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    Quote Originally Posted by astral171988 View Post
    Greetings Pakwheelers,

    I have a 2015 Corolla xli, maintained by Toyota Gujranwala with a mileage of 10k. Car is mostly city driven so I have to change gears a lot. Now sometimes when I shift from 1st to 2nd gear, I'll hear knocking in the engine for a split second before disappearing, especially with ac on. I shift into 2nd gear with an rpm that is usually +1k. I use a mixture of normal to high octane petrol in 80:20 ratio.

    To all other owners, is this behavior normal? Can it be eliminated/minimized? Do I need to rev match and get the rpm to +2k before letting go of clutch? What are your experiences/suggestions?

    Ps. Anybody know which pump sells good petrol in sialkot, do tell
    Light and occasional knocking can be acceptable. All the time and heavy or medium knocking is not good and not acceptable. I have left using manual cars since 2010 and prefer automatic for many reasons; the automatic transmission has one of the great advantage that it usually does not allow knocking at least from driving parameters (not referring to bad fuel etc.).

    Use of Hi-octane is usually a myth especially with regard to fuel economy. No doubt it will not knock (pre-mature explode in compression stoke) but one should go for good quality normal (Super) petrol. What is the guarantee that the petrol pump selling regular fuel of low quality would not sell low quality Hi-octane. Please note that Toyota 11th Gen (2NZ-FE, 1ZR-Fe and 2ZR-FE) are good for regular fuel with Reasrch Octane Number (RON) of 91 or higher. Avoid wasting money on Hi-octane and find a quality petrol pump BUT pay attention to your driving as you very rightly pointed out yourself.

    I drove GLi manual 1.3 11th Gen 2015 of my cousin for brief 5 km only and came across knocking too. BUT I contribute this to my driving in which I inadvertently did gear shifting at much low RPM.

    YES! You are 100% right in my opinion (keeping other factors aside) that you should REV up to higher rams before shifting. How much high rpm? Please experiment at various revs and find the most suitable ones.

    PS: Knocking is produced because of pre-mature fuel burning/destabilising and should be avoided as it causes very high frequency vibrations of engine walls which if happening very often would result in damage!

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    Brother, i also faced same knocking issues, now it has been resolved after taken two action by me. 1. please increase Hi-Octan ratio, now a days Rs 3000/= fuel required to filled in almost full empty tank, so i distribute it 3000 = 2000 ( normal fuel) + 1000 (Hi-Octan). 2nd cleaned the dust sensor ( you have to specially ask 3s dealer to clean it). jazak ALLAH.

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    @bridgedoctorali Thanks for the detailed explanation. Btw, RON of pakistan fuel is 87 (on paper, atleast). So to achieve a RON of 91 like you suggested inadvertedly means I need to increase the ratio of high octane.

    @Forcian I'll get that dust sensor checked next time I got maintenance done.

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    Quote Originally Posted by astral171988 View Post
    @bridgedoctorali Thanks for the detailed explanation. Btw, RON of pakistan fuel is 87 (on paper, atleast). So to achieve a RON of 91 like you suggested inadvertedly means I need to increase the ratio of high octane.

    @Forcian I'll get that dust sensor checked next time I got maintenance done.
    Hmmmm very right! Well two responses. If Super is RON 87 then its on lower side and needs more RON; however automatic car adjusts valve timing and many other parameters and takes feedback from Anti-Knock sensors to avoid/minimise knocking.

    Regards

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    Quote Originally Posted by bridgedoctorali View Post
    Light and occasional knocking can be acceptable. All the time and heavy or medium knocking is not good and not acceptable. I have left using manual cars since 2010 and prefer automatic for many reasons; the automatic transmission has one of the great advantage that it usually does not allow knocking at least from driving parameters (not referring to bad fuel etc.).

    Use of Hi-octane is usually a myth especially with regard to fuel economy. No doubt it will not knock (pre-mature explode in compression stoke) but one should go for good quality normal (Super) petrol. What is the guarantee that the petrol pump selling regular fuel of low quality would not sell low quality Hi-octane. Please note that Toyota 11th Gen (2NZ-FE, 1ZR-Fe and 2ZR-FE) are good for regular fuel with Reasrch Octane Number (RON) of 91 or higher. Avoid wasting money on Hi-octane and find a quality petrol pump BUT pay attention to your driving as you very rightly pointed out yourself.

    I drove GLi manual 1.3 11th Gen 2015 of my cousin for brief 5 km only and came across knocking too. BUT I contribute this to my driving in which I inadvertently did gear shifting at much low RPM.

    YES! You are 100% right in my opinion (keeping other factors aside) that you should REV up to higher rams before shifting. How much high rpm? Please experiment at various revs and find the most suitable ones.

    PS: Knocking is produced because of pre-mature fuel burning/destabilising and should be avoided as it causes very high frequency vibrations of engine walls which if happening very often would result in damage!
    Adding to it try to get your car filled only from Total Pumps as their normal petrol RON is 90 . PSO 90 means 80 and below as PSO is procuring Irani fuel.

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    Quote Originally Posted by khuram2703 View Post
    Adding to it try to get your car filled only from Total Pumps as their normal petrol RON is 90 . PSO 90 means 80 and below as PSO is procuring Irani fuel.
    also PSO is not purely unleaded so also detoriates catalytic converters.

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