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Nickbryan

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Hey guys im new to the fourm, ive been having trouble with my silvia ever since i replaced the head gasket, now im not too sure what it is but it sounds liking detonation when ever i put my foot down the slightest, im a bit scared to drive it, and there is also a tapping at idle but this could just be a rattle.
Cheers
 
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Hey guys im new to the fourm, ive been having trouble with my silvia ever since i replaced the head gasket, now im not too sure what it is but it sounds liking detonation when ever i put my foot down the slightest, im a bit scared to drive it, and there is also a tapping at idle but this could just be a rattle.
Cheers
I didnt think you could here det, you need a knock sensor for that dont you?

Sounds like it could be just missfiring, check the plugs arent covered in crap or broke etc gapped right if your using colder plugs and running more boost? Check the coils too..

Tapping could be vvt rattle.
 
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Nickbryan

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Thanks yea have checked the plugs and re gapped them, tried new fuel its like pinking sort of noise, and how can you tell if its vvt rattle?
 
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Nickbryan

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pretty sure they were, my father is a nissan mechanic and has worked on them for over 20 years and its running factory ecu
 

S15_SAM

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Tbh mate sounds like you've put something together wrong! If the noise wasnt there before then it's defo a **** up on putting it together! Most likely the timing chain related! Take to a specialist or strip it again.
 
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Nickbryan

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i put new plugs in just before i took it off the road so i can think it maybe that, whats the best plugs to get to test?
 
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any off the shelf NGK's with a heat rating of 8 or higher. Sounds like something was put together wrongly after the stripdown.
 
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Nickbryan

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okay i changed the spark plugs back to the champions that where in it that have a heat rating of 8, since putting them in it idles nicer, but havent taken for a drive yet, also was listening to the noise and could be coming from exhaust side, has anyone heard of a wastegate making noises like that? (external)
 
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martinbattye

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if there was a LOT taken off the head there could be a problem..

my bet is that you have got the CAS incorrectly aligned and the CAS timing is out by a few degrees.
 
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okay i changed the spark plugs back to the champions that where in it that have a heat rating of 8, since putting them in it idles nicer, but havent taken for a drive yet, also was listening to the noise and could be coming from exhaust side, has anyone heard of a wastegate making noises like that? (external)
If you suspect the exhaust side then working from the turbine downwards:-

1. Are you using an actuator type wastegate? If you are and if it happens to be a HKS item, losing the c-clip that holds the treaded shaft that mechanically controls the flap within the turbine could be loose and so its rattling away longitudinally...U can feel it as you accelerate and are about to run boost and then let off the gas pedal you'll hear a rattlesnake-like sound.

2. Most aftermarket exhaust systems after the downpipe are 2 piece. So check all flanges are ok and the bolts between flanges have not sheared causing it to bang against each other.

3. Its uncommon for the spring within the external gate itself to dislodge but its worth checking anyhow.

Hope that helps.
 
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