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Pfc Tune Result R33gtst

benl1981

By benl1981,
in Engines & Forced Induction

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Spook's_Skyline Mentor

Spook's_Skyline

Posted
Posted

i got a bit of knock reading after my powerfc tune, but its all settled down nicely

i got 195rwkw with similar setup (r32 gtr cooler with modified forward facing plenum)

i dont see knock above 20 these days

RS500 Experienced

RS500

Posted
Posted
Spoooks - did you do anything to cause the knock to settle down?

I just got to knock of 61 as I got high in the rev range in 2nd gear.

you will see this kind of behaviour if u have the standard intercooler.

what happens is that after a few WOT (Wide Open Throttle) runs, the i/c absorbs a lot of the heat produced by the turbo, as to allow cooler air to be ingested into the engine. Although, this heat absorbed by the i/c greatly reduces the cooling efficiency and given that the standard i/c core is very small in size, dissipating this heat will take a while.

so what u need to do after you go for a nice WOT run thru all the gears, is cruise the car (off boost) for 5-10mins as to allow the i/c to release the heat by the flow of ambient air thru the i/c and monitor your intake temps and knock (if u can) at all times.

if you're not doing this, then your intake temps will be increasing quite a lot which would cause the knock that u see.

benl1981 Grand Master

benl1981

Posted
  • Author
Posted (edited)

I had only given it a bit of a hit in 1st then 2nd..I dont think this is heat soak. The tuner reckoned I could take it to the track the way it is with the R34 SMIC on it..

I realise a FMIC would be a bit better though...

Edited by benl1981
  • 2 weeks later...
benl1981 Grand Master

benl1981

Posted
  • Author
Posted

Just to let you know I spoke to the tuner and a few others - apparently you can get a flash of the engine light in 2nd gear, knock sensors can pick up mechanical noise. Mine only flashes once or twice so may not be knock.

Mine hasn't done it much now.

Fuel economy is 10.65L/100km with some 15km one way trips (not too many traffic lights) and some longer 40km one way drives. Gave it a little stick from time to time but tried not to waste fuel by slowing and accelerating when trying to maintain speed.

I have probably gained 1-1.5L/100km. Difference would be more if you used a lot of throttle aswell.

At peak airflow - about 5010mV I think injectors were about 68% whereas before they were about 85% or something.

  • 2 weeks later...
Cubes Grand Master

Cubes

Posted
Posted
At peak airflow - about 5010mV I think injectors were about 68% whereas before they were about 85% or something.

Don't be dissapointed with the power figure..

The 5010mV airflow figure reveals all.. :D

The dyno I run mine on I was pulling 4.98v to make 176rwkw.

So on my dyno with the motor ingesting 5010mV of air you would be pulling 180-190rwkw.

RB25DET's on my dyno generally pull around 190rwkw with 11-12psi.

So you are definitely making good solid power for 10psi.

benl1981 Grand Master

benl1981

Posted
  • Author
Posted

Thanks Cubes. Yeah I'm pretty happy. You think the AFM voltage is a reasonble indication of power?

I'm getting the check engine flash a little in 2nd gear. I have seen knock hit 80. I called the tuner and he reckons that it is mechanical noise. When you lean out the mixtures he reckons that the silly mics pick this up more. He reckons he can richen it up and it will stop the knock readings but also kill power.

On the dyno he kept knock below 20. I also asked him if I see it flashing should I back off and he sort of said not really.

He is the tuner SK uses so is very good. Bit disheartening when you see the engine light flashing though..

The Mafia Grand Master

The Mafia

Posted
Posted

just be careful though, I know every knock sensor is different, but my tuner said that knock in the head phones was audible when the Powerfc read 80 on the hand controller.

He said it was JUST audible, like barely audible at 80.

So If I keep mine below 40 I will be fine. 100 must be pretty bad though, I saw a few 100's pop up when I upgraded the turbo and had a ghetto tune in before I had a proper tune. Scary when you hear the popcorn sounds..

Cubes Grand Master

Cubes

Posted
Posted
Thanks Cubes.  Yeah I'm pretty happy.  You think the AFM voltage is a reasonble indication of power? 

I think it is.... Its the amount of air the motor is ingesting.

How well the motor then uses that air is up to the tuner with regards to afr's and ign. timing. This is where its worth comparing WOT ign. values. :D

rob82 Mentor

rob82

Posted
Posted
just be careful though, I know every knock sensor is different, but my tuner said that knock in the head phones was audible when the Powerfc read 80 on the hand controller.

He said it was JUST audible, like barely audible at 80.

So If I keep mine below 40 I will be fine. 100 must be pretty bad though, I saw a few 100's pop up when I upgraded the turbo and had a ghetto tune in before I had a proper tune. Scary when you hear the popcorn sounds..

I've found on the RB25's that a knock reading around 40-50 can be heard through a chassis ear but is not audible to the ear, however a knock reading around 80 is most defintely audible to the chassis ear and the naked ear.

benl1981 Grand Master

benl1981

Posted
  • Author
Posted

I find If I full throttle second gear on the flat I don't get much knock. But if I load it up going up a hill..hoild it at 3500rpm and hit it, I will get the 3 flashes from the check engine at about 5000rpm.

I might talk to the tuner again or get him to look at it. Don't want it to be unsafe.

Cubes Grand Master

Cubes

Posted
Posted

Its well known cars with lower diff ratio's are able to get away with a little more ignition timing, increase the ratio (numerically decrease) and you will have to pull some ign. timing out.

It may be spiking a little at 3500rpm causing det also. :rolleyes:

The way mine is tuned now I can drop it in fifth up a hill and I will get high knock values... BUT how often do I do this.. never. :cheers:

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