Knock Values On Powerfc

[Spook's_Skyline]

ok, got my powerfc and cam gear pulley (exhaust) installed late last week

going really well, despite my exhaust killing power totally (its going to get replaced)

anyway, drove the car for a few days, went down the coast etc

all good

last nite however i noticed the engine warning light come on a few times during boosting

check my knock readings

132!!!! (that seems extremely high, the tuner told me there shouldnt be anything about 40

today driving even on low boost, no engine lights, but its reading 50-70 when boosting moderately

is that too high?

what can cause knocking that would have changed since i got the car?

i filled up with bp ultimate donw the coast

didnt notice any high values for the first few days of having the car

did notice however, that when boosting hard, theres a pause/dip when i change gears

1st goes hard, then when i change to second, pause, then hard acceleration

doesnt feel right

dont seem to notice it as much on low boost setting

appart from that, powerfc and tune seems to have fixed all my idle problems (appart for a bit of a hunt for idle with the aircon on everynow and then)

no stalls at all, which i used to get every now and then

[Cubes]

Too high.

Over 45-50 and I would be worried.

[benl1981]

Have you looked theought the PFC settings to check if it hasn't lost the tune or something. Could be a bad batch of fuel I guess...

Id be going back to where you got the tune. Maybe he didnt tighten upo the adjustable cam gear preoperly and thats lost its position?

Bit off topic but I saw the check engine light flash once but the peak knock was only 39. I did hit rev limit - does that trigger the light?

I didnt max anything else out like AFM or anything..

I once saw 94 but it didn't trigger the check engine. Somebody said it may have been a one off knock

I wouldnt boost much at all till you get it looked at - the sooner the better..

[Spook's_Skyline]

yer, ill just call them tomorrow

i have to admit, the car felt differnt last nite

much angrier than the original nite i got it back

its got a powerfc boost conctrol as well

[gawdzilla]

Also curious about this... at what Knock value does the pfc trigger the check engine light? I have heard @ 60.. is this true?

So anything under 45 is considered "safe" knock? if no, what is a "safe" knock value??

I am seeing some (up to 25) just motoring around.... can anyone give insight on their max knock values (if any) while just driving around normally (off boost)? thanks

Edited November 21, 2005 by gawdzilla

[The Mafia]

yeap, 60 and above triggers the engine light.

Anything over 40 - 50 and I'd be doing something fast, like pulling the boost back 3 or 4 psi. If that doesn't stop it, I'd pull it back some more.

[Cubes]

So... Set the dash trigger value to 50 with your new datalogit.

[horn]

I get 22-25 on the gtr on a safe tune.

[benl1981]

I've sen 80 withoutit triggering engine light. I think it as to knock for a predetermined time - so a one off 80 or 100 may not trigger the light...

[N I B]

I had a GTS in last week that reads 95 no matter what we did with it,We even backed the CAS of as far as it would turn dropping power from 320rwhp to 246 ,Still 95 knock count,fuel is at 11.5-1 and 16psi with a HKS 2540 turbo.

We changed knock sensors, put a remote knock sensor on and it did not ping.so we upped the timing using the remote counter till it had a light ping and the PFC still read 95.

So this leaves me thinking dont ever trust the knock readout alone.

[R31Nismoid]

mine never went above 20

unless i hit the limiter and then it generally can read odd numbers but thats ok.

And yeah, sometimes the knock sensor does get sick

[Mushroom]

I currently run a haltech ecu that doesn't use knock sensors should i look at getting an aftermarket reader or something like that?

[wilch]

If mine hits 30 I back off, and turn the boost down.

In normal weather on spirited drives it peaks at 20.

There's a post somewhere where I think sydneykid mentions that their cars are tuned to the limited (close to 60 knock values) or something, but that's only cause they rebuild the motors frequently....

[R31Nismoid]

i doubt SK would have said that based on them rebuilding motors often.

why would you wanna do that if you dont have to

[Chris32]

Good 'ol knock sensors

Mine is still giving me the shits

I think it got a bit damaged when I had my new exhaust made up, the earth for the welder was attached near the knock sensor or something

Mine is stange, some days it will hit 80-90, other days 30odd. I have heard it ping a few times, and it showed about 130 on the h/c. Mainly to me being silly!

Playing around with injector correction % on each injector now. Last night I went through each injector and added 2% more fuel to see if it would help with my random knock

Injector 4 showed the most improvement, knock going from 80 to 24 at 1.3bar

Maybe I am finally onto what my problem is?

Either way, the knock sensor is more of a guide than a rule, each cars knock sensor will read things a bit differant, best way is to check it on the dyno and see when you can hear it knock and see what the h/c says

engine check light comes on at 60

[Tommyk]

agreed

if you're getting knock over 30, then you need to do something about it.

Play with the ignition timing correction and/or the fuel correction. reduce timing and/oro add fuel and see if that fixes the problem. I added a bit of timing and added a bit of fuel and the car goes a lot harder (added 4 degrees and about 8% fuel) and i get knock in the 20's

[Cubes]

I've found if its tuned and does get knock over 35 'OCCASIONALLY' under certian circumstances it will also spike to over 60.

[Spook's_Skyline]

well, i think i had a bad batch of fuel

as most times now its fine barely registering 20

although coming back from stanthorpe with a full car, aircon on and wot in 5th gear

it did register 90, but no dash light;

appart from that it was less than 20 for 95 percent of the trip;

ill just keep an eye on it for now

[Tommyk]

maybe reduce the timing a bit.

Or try to add a bit more fuel to compensate.

How was it tuned on the dyno, in relation to the a/f ?

[williamsf1]

I'll think you find that the corrections you can make are a 1 time affair.... i.e. if you turn the car off, it is erased....

I guess if your willing to do it each time, then go right ahead...