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R32 - with DEATH rattle

itbmils

By itbmils,
in Engines & Forced Induction

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itbmils Proficient

itbmils

Posted
Posted

Guys

OK - I've asked this question before - but I'm still not sure if I have a MAJOR problem or not.

I have just done a full engine rebuild on my R32 GTR - and fit up a new PFC in the process, and I think I'm getting some knocking – but I'm not sure.

Firstly - I've used wiesco forged pistons - and I want some feedback as to how noisy this pistons can be. The reason I ask is that I consistently get high knock readings (~40ish) from my PFC, mainly when the engine is cold. This is even under VERY light load.

Secondly – how accurate are the PFC knock readings – are these something I can trust as a accurate reading for pre ignition, or could I still get pinging that does not register on the PFC.

Lastly - I also notice what I will describe as a rattle - when the engine is under light load. (It may happen under heavy load – but I just can't here it over the engine note)

Lets say I'm highway driving at about ~80klms and I come to a slight hill. I squeeze the throttle just to maintain speed as I pull up the hill - and I get the rattle. This happens at low boost under almost no load (~3000rpm). Could I be getting knock under almost ZERO load ?

The noise is high pitched, high speed rattle or ticking. It sounds a lot like cold forged pistons or even tappet rattle to me - but it happens even when the engine is hot.

Talk to me guys - is this a death rattle ?

The PFC was installed and tuned by Mazfix here in Brisbane – and they assure me they had no knock during the tune process. They are also happy to have another look at it for me.

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https://www.sau.com.au/forums/topic/81406-r32-with-death-rattle/
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Beer Baron Grand Master

Beer Baron

Posted
Posted
Guys

OK - I've asked this question before - but I'm still not sure if I have a MAJOR problem or not.

I have just done a full engine rebuild on my R32 GTR - and fit up a new PFC in the process, and I think I'm getting some knocking – but I'm not sure.  

Firstly - I've used wiesco forged pistons - and I want some feedback as to how noisy this pistons can be. The reason I ask is that I consistently get high knock readings (~40ish) from my PFC, mainly when the engine is cold. This is even under VERY light load.

Secondly – how accurate are the PFC knock readings – are these something I can trust as a accurate reading for pre ignition, or could I still get pinging that does not register on the PFC.  

Lastly - I also notice what I will describe as a rattle - when the engine is under light load. (It may happen under heavy load – but I just can't here it over the engine note)

Lets say I'm highway driving at about ~80klms and I come to a slight hill. I squeeze the throttle just to maintain speed as I pull up the hill - and I get the rattle. This happens at low boost under almost no load (~3000rpm). Could I be getting knock under almost ZERO load ?

The noise is high pitched, high speed rattle or ticking. It sounds a lot like cold forged pistons or even tappet rattle to me - but it happens even when the engine is hot.

Talk to me guys - is this a death rattle ?

The PFC was installed and tuned by Mazfix here in Brisbane – and they assure me they had no knock during the tune process. They are also happy to have another look at it for me.

it sounds like pining to me. FTR load is not the same as RPM. load is used to describe how much load the engine is struggling against. so going up a hill at 80km and low revs and squeezing the throttle even to 15% at 3000 the engine will be under a lot of load. this can be demonstrated by slipping clutch. it may be fine reving and changing gears at 7000rpm in first and second, but cruising along the highway in 5th at 2000rpm and squeeze the throttle and it will slip this is because the engine is under more load.

PHATGTR Collaborator

PHATGTR

Posted
Posted

My understanding was that forgies were renowned for increasing the knock level on Power FC's?

I have had a Power FC in 2 different cars now and I think that if your car was actually pinging as hard as everybody thinks it is, the knock reading would be much higher than 40.

How recent was the rebuild, because sometimes things just aren't fastened or tightened properly.

Is there a chance it could be something as simple as a heat sheild? :confused:

Cubes Grand Master

Cubes

Posted
Posted

I run wiseco forged pistons in my RB30DET. The pistons I use are to suit the RB25DET with a 14cc dome.

I run the largest recommended bore to piston clearance of 0.0040, this is to suit 24+psi and or race use.

The have a slight slap on cold start that sounds like a quiet noisy cam. Only I can hear it, my other half can't, either can my old man.

On a cold start I get a maximum knock of 10 on the PFC H/C, idle it sits on 1.

Cruise knock sits on 1, even when cold.

Once warm at WOT, the max knock I get is around 18.

Light load up hill accelerating might see a knock of 4-5.

With the standard recommended bore clearance the Wiseco's have absolute zero slap on a cold start.

Run thier largest recommended clearance and they will have a real slight slap on idle that as said, can be mistaken for a noisy cam.

I've now done around 20,000km's on the motor, still perfect. :rofl:

I suspect the tuners fiddled with the light load ignition map, causing detonation under light load.

If you have time write down the ignition map and post it up. I will let you know whats been modified.

I once bumped up my light load ignition map and noticed high knock readings at cruise when the motor was cold. I put this down to the richer mixture was burning quicker as a result knocking as obviously peak combustion pressure was occuring too early.

Duncan Grand Master

Duncan

Posted
Posted

It might also be that you have accidently advanced the exhaust cam 1 tooth when you put it back together.

The PFC knock reading takes a analogue signal from the knock sensor (basically a mic) and tries to interpret the correct noise for knock , same as the standard ECU does. It is not perfect, it can pick up other noise as knock. Possibly it may miss genuine pinging too, I would not trust it as the only thing to watch

  • 5 years later...
NSNPWR Rising Star

NSNPWR

Posted
Posted

Thread mining!...

Its the PFC Boost Control solenoid rattling, hard mounting it to the strut tower will do that...sigh...and I know because I have this car now...what a farkin junk box it was...lol...nothing some love couldnt fix...QLD guys cant mod a car for sh1t...butchers.

FineLine Grand Master

FineLine

Posted
Posted

Thread mining!...

Its the PFC Boost Control solenoid rattling, hard mounting it to the strut tower will do that...sigh...and I know because I have this car now...what a farkin junk box it was...lol...nothing some love couldnt fix...QLD guys cant mod a car for sh1t...butchers.

I'll pass on your compliments to the Berry/newman boys, Mark jacobsen etc.

NSNPWR Rising Star

NSNPWR

Posted
Posted

I'll pass on your compliments to the Berry/newman boys, Mark jacobsen etc.

Did they have a hand in the build of this car, no?...Probably a very general statement I made but im talking about your average backyard tinkerer from up that way...doing sh1t like screwing number plates straight into bumpers, terrible wheel choice and fitment, chopping holes in inner guards with what looks like an oxy torch, using PVC pipe fittings and tek screws...wheres the love!?

FineLine Grand Master

FineLine

Posted
Posted

Did they have a hand in the build of this car, no?...Probably a very general statement I made but im talking about your average backyard tinkerer from up that way...doing sh1t like screwing number plates straight into bumpers, terrible wheel choice and fitment, chopping holes in inner guards with what looks like an oxy torch, using PVC pipe fittings and tek screws...wheres the love!?

LOL! Be more specific next time.

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