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PFC knock reading

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lj~R

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This is realy annoied...my pfc's knock reading quite high since first dyno tuned. I went back to see tuner (twice)and get it retuned (like pull the timing back, mixture...etc) but won't help. The knock reading has gone to 79 in 2nd gear 5700rpm (water temp is 82c)and most of time when i boosted knock reading always go over 40~90. Also when the water temp is around 75c I rev up to 5200rpm the knocking reading is 15.However, no boost during I drive the reading always under 10. So today, he reckon that should be knock sensor problem coz he has done whatever he can to help me on pfc settings. What could be potential problem except knock esnsor faulty? If its faulty sensor that would be great what if not?are second hand knock sensor reliable? I look on ebay few guys selling one for $44 USD ,are these ok to buy?


Cheers
 
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meddler

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silly question, but what fuel are you using?
 

meddler

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I would also suggest it's a faulty sensor. If you get a second hand one you can you it to test to see if your one is faulty. Obvioulsy depending on it's price you would have to decide on buying a new one would be more cost effective.
 
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gunner93

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I've been told not to take the readings as 101% because the knock sensor also detects other vibes not related to detonation. You may swap with a friend to check.
 
L

lj~R

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I might just buy a cheap one to run first. Got a quote from a guy said $200 nzd for a brand new knock sensor...
I've read through some topics about pfc knock readings, some ppl said that could be rear subframe or exhaust is shaking causing the problem. Isn't the knock sensor sitted under the starter motor?
 
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The knock sensor on my PFC doesnt go above 8 even on boost I think RC Developments set it last time I was there because it was left on the knock page.
 

S15_Spec_R

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Whats your battery like? Mine had a dead cell and under norm al driving I get got a max of 12 points but as soon as I gave it some welly and was around the 100+ mph area I started to get readings of 60+. Changed my battery as it had a dead cell and now no more than 8 points even at high speed with a running water temp of 80 c and oil 72 c. Hope that helps.
 
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lj~R

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I went down to my car, seems a front pipe bracket which is almost close to another part maybe that's the thing. However,ive cut it off now and went for test drive, i rev up to 7000rpm on 1st and 2nd gear the pfc shows the highest reading was 26. Seems to be ok but don't have enougt fuel to do more run on that time. Anyway, I'll keep tracking to see if knocking reading still go above 30.
 
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