Apexi Pfc Knock Readings!

[ScarifieR32]

Hey

I just got my car back from X Speed

they are reknown tuners for powerfc and ant scali knows his stuff

The car over all runs pretty good and the knock levels are ALWAYS below 20

Except once last night i got cut off by a car and went past him on gate in 4th gear

it rev'd out to 5600rpm and read a knock of 126?

i was concerned and cleared the hold settings , put it in 3rd and reved it out to 6000rpm and it didnt go above 14 (did the same 4-5 times more that night still the same)

Am i worrying for nothing? because basically its cost me a small fortune to upgrade to the 25 after blowing 2 rb20's in my 32 and i really dont want to blow another engine

its tuned very safe - no timing at 14psi with 11.8 afr and lower with a max power of 312hp

Also is it possible for a rock or something making a noise in the engine bay to cause a knock reading?

Im new to the pfc so any information will be appreciated!

[Kaido_RR]

did you hit the limitter?

normally i dont get knock above 20 but when i smash the limiter i sometime see knock values above 70.

If your really not happy take it back, and explain your problem and they should be able to help you out. Should be free of charge too

[GTS-t VSPEC]

Quite often a high knock like that would be due to mechanical noise, not from pinging. If it's not repeatable then I wouldn't be too concerned.

[ScarifieR32]

that reply eases my mind a bit

[ScarifieR32]

im happy with everything i just worry because of the money its cost and the previous hassles ive had with everything prior to going to x speed

i just found out its got a bad leak from the mani at the back near 6th cyl which i thought was the dump pipe

could this of had something to do with it?

maybe a flame out the side of the mani which caused a bang? i dont know?

but yeah its not repeatable and hasnt gone into the 20's otherwise

paul if its not a prob check my reply on another thread and post your thoughts!

http://www.skylinesaustralia.com/forums/in...p;#entry3295944

cheers

[GOT BOOST]

you can actually be getting high readings on de accel

[Leadfoot]

Please check my post on your other thread.

However, in brief, I have had exactly the same problem just recently and have good reason to believe it is due to the tune.

I can repeatably induce knock in the 50 to 80 range without hitting rev limiter and have since reduced boost to 0.9 bar until this is sorted.

I seem to need a slightly less aggressive tune than Xspeeds standard tune due to track use and a more aggressive driving style/vehicle usage.

I will say this is probably my own fault for not advising Xspeed that the car is used at AHG for racing purposes.

Also, Ignition was breaking down during the tune due to old plugs and 1.0mm gap even with splitfires.

The tune was not 100% completely finished and needed another hour on the dyno.

Nevertheless, the "random high knock" is real and repeatable and needs to be sorted before any more track use.

[ScarifieR32]

yeah i got them to tune it as a safe safe tune and hence they took timing out up top and left everything else standard on the timing side of things

ant said if it had timing put into it aswell as ultimate fuel (tuned on vortex) it would make 350 easily on 1 bar

im not after max power

all i want is reliability with a bit of poke

so far im very happy with everything , im just cautious because of the money and stress the car has caused me

the main reason i chose a pfc is because of the knock sensor reading and when i seen a high reading i worry

i just want to enjoy it and drive it from now on without the stress!

[SimonR32]

did u check after you started the car what your knock levels were...

the starter motor turning in my car gets around 115 most times.

i also get a lot of engine noise in decel, but thats because my engine is fairly loose

[noone]

Leadfoot am having fairly similar problems with my tune knock to about 80ish right as she gets up on boost, have missed track days trying to sort it damn frustrating

Just wondering if you dropped to a lower heat range plug when you put the splitfires as they reccomend, I didnt.

Also curious if you had tried the settings recommended here

http://www.skylinesaustralia.com/forums/in...p;#entry3298482

[ScarifieR32]

true

well nah i dont know what it was on but im pretty sure it was when i said

and its never happened since then but yeah i rang xspeed and ant said theres no way it would of been a legit ping coz of the way he tuned it

he said it could of been a rock flinging up or the gasket but definately not the tune

otherwise it hasnt gone over 12-14 since that night

and boost definately isnt spiking either!@

[J_R32]

like Cerbera said, it also could be caused by loose stuff within the engine bay. my friend has f**ked engine mounts in his old car and once in a full moon when he gave it stick it would read in the low 100's. daily driving never more than 20..so check for loose stuff

[Leadfoot]

Leadfoot am having fairly similar problems with my tune knock to about 80ish right as she gets up on boost, have missed track days trying to sort it damn frustrating

Just wondering if you dropped to a lower heat range plug when you put the splitfires as they reccomend, I didnt.

Also curious if you had tried the settings recommended here

http://www.skylinesaustralia.com/forums/in...p;#entry3298482

The tuner told me I need to fix a few things first before going back for a retune. They were getting spark breakdown under high load meaning they could not tune for over 360rwhp at around 1.0bar. Apparently each dyno run was also inconsistent to the previous making it hard to tune.

The breakdown problem was the long life irridium plugs gapped at 1.0 mm. I was advised to go back to copper at 0.8mm. Once the plug electrode carbonises it will breakdown regards of being copper, platinum iridium or whatever. Gapping the iridiums to 0.8mm seems to have fixed the problem however it may now just be partially breaking down and causing knock. At 1.2bar I consistantly get knock up into the 80's.

I also found I had a leaking PCV valve that was bypassing under boost back through the catch can (not measured by the air flow meter) causing it to lean out.

That would have been the cause of the inconsistency. Another possibility is cheap chinese imitation Z32 air flow meters. Proper z32 airflow meters are packed in a yellow bosch box and has bosch written on it. It is also possible that the CAS alignment is out meaning that TDC could be a few degrees more advanced than what the PFC says.

Once I have fixed all these items and pressure tested the intercooler and connecting hoses for leaks I will go back for a retune and see what happens.