Knocking sometimes on throttle on | FerrariChat

Knocking sometimes on throttle on

Discussion in 'Boxers/TR/M' started by bensonae, Jun 11, 2017.

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  1. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    OK I thought I had a loose AC belt since I could hear it clearly at start up and calmed down after warming up. I tightened that and seemed to go away(On another thread Shamile described the sound which sounded like my issue). But I have a knock that is intermittent that usually does not happen until the car is warmed up and under throttle (higher loads). I thought it sounded like it was coming from the passenger side but my ears might deceive me. I saw a flash of one of the slow down lights for a split second and a temporary loss of power. I was thinking the sound might be a spark plug fouling or possibly a bad fuel injector? My plugs were replaced 4 years ago and have done maybe 10k km so not much. 99% of the time there are no symptoms and the power is 100%. Idles perfectly. This is only ever under load(throttle on) and when the car is warm/hot. Seeing as it is an audible knock it is nerve racking despite it only occurring rarely. I checked plug wires one was a bit loose but I do not think that is it. Any ideas?
     
  2. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,866
    southwest germany and thailand
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    romano schwabel
    could you describe this "knocking" or the sound of this knocking better please?
    is it frequently like the rpm?
     
  3. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    It seems to be audible more around let's say 2k-4k rpm or so. i can only hear it at low speeds(road speed not engine speed). It almost sounds like metal on metal rattling like something is loose. It is strange though as it does not make the noise when I lift off the throttle. I am tempted to let the mechanic just take it and figure it out but I wanted to do some self diagnosis first.
     
  4. daytonaman

    daytonaman Formula Junior

    May 1, 2007
    959
    Australia
    Full Name:
    howard pigdon
    timing retarded or not advancing
    Pinging/pinking
    Get it adjusted asp
     
  5. 166&456

    166&456 Formula 3

    Jul 13, 2010
    1,723
    Amsterdam
    #5 166&456, Jun 12, 2017
    Last edited: Jun 12, 2017
    The symptoms described seem to match with rod knock. This can be heard around the revs you mentioned at light to moderate throttle. Higher rpms or speed will usually drown out the rod noise. It will be a lot less or unaudible when off throttle and often also when the engine is cool and/or idling.
    The problem is, rod knock is relatively rare. It has specific causes, the main ones a history of either oil starvation or an overrev event within the (recent) engine's history. How likely that is, you as owner are probably best to say.
    Should it be rod knock then very soon you may have a few large vent holes in your engine block and a very high bill to fix it.
    If it is not rod knock you may still find yourself paying someone a great deal to inspect the bottom end.

    Point being - find someone who you are sure you can trust with diagnosis. Someone accurate and knowledgeable in locating its origin, as well as honest to not still scam you out of a lot of money if nothing is wrong.
     
  6. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,866
    southwest germany and thailand
    Full Name:
    romano schwabel
    you are sure it is coming from the engine?
    not the gearbox? diff?????
    you write when you lift off the trottle you not hear the noise, what about when you accelerate? and what when you are just only driving with constant speed?
     
  7. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    I am not sure it is coming from the engine at all. It only happens on throttle not off. At constant speed i can not hear a thing which is why I am inclined to think it is not a rod knock which i would have thought was constant. At constant slow or fast speeds(road speed) I hear nothing wrong ONLY when I accelerate aggressively at low road speeds(Could be inaudible on the highway).
     
  8. turbo-joe

    turbo-joe F1 Veteran

    Apr 6, 2008
    8,866
    southwest germany and thailand
    Full Name:
    romano schwabel
    #8 turbo-joe, Jun 13, 2017
    Last edited: Jun 13, 2017
    take the car on a hoist and let it run. one may sit inside and accelerate and the other under the car may listen. if no noise then the one inside may brake a little and accelerate a little more.
    but may be you will hear nothing.

    on my competition it was the same, only when hard accelerating I had this terrible noise. when normal driving or decelerating there was nothing. but is was so terrible that I did not go over 60 km/h. it was a broken diff and also a broken pinion ( teeth have been broken )
    on the hoist I had not hear anything, only when driving on the road.

    the sound has been like a knocking in the drive shafts from the gearbox to the wheels

    hope for you it will be not as bad :)
     
  9. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    Fingers crossed.....
     
  10. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    Mechanic says I have a bad throttle position sensor as well as a crankshaft(phase) sensor. Also running very low on R134a in the AC compressor. Hopefully this solves the issues!
     
  11. Melvok

    Melvok F1 World Champ
    Owner Silver Subscribed

    Jul 25, 2008
    14,101
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    Mel
    Yes, hope so too.

    A diff problem is not waht tou are looking for imo ... :) Did you already upgrade Alex ?
     
  12. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    No diff upgrade. Fuse box needs to be done maybe over the winter. There's a bit of heat damage as seems typical.
     
  13. lear60man

    lear60man Formula 3

    May 29, 2004
    1,829
    Los Angeles
    Full Name:
    Christian
    I had a throttle on ticking noise coming from the passenger side rear. Scared the life out of me. Turns out the last time I had new tires put on, the tire guy put the tire weights too far inboard and they were hitting the A Arm, but only under load. Easy fix, hope you have the same luck.
     
  14. Melvok

    Melvok F1 World Champ
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    Jul 25, 2008
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    Mel
    Any news Alex ?
     
  15. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    Not back yet. I'm off on vacation soon so may be a few weeks before I get her bsck.
     
  16. Melvok

    Melvok F1 World Champ
    Owner Silver Subscribed

    Jul 25, 2008
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    Have a nice vacation Alex ! :D
     
  17. bensonae

    bensonae Formula Junior

    Apr 7, 2013
    284
    Tokyo, Japan
    Full Name:
    Alex Benson
    Sorry for delayed response Melvok. Replaces both TPS and the crankshaft sensor. Also recharged the AC. Seems to have fixed it all up. Running superb although i have barely been able to use it this year
     

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