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Discussion Starter · #1 ·
been out again today i was previously seeing 42 tops knock on the power fc.
filled it up with petrol and im seeing consistent 50 - 55 above 6k revs. boost is at 1.45 bar, so i dropped the boost to 1.2 bar but readings were exactly the same ? drives and pulls perfect and if it was a slighlt lean issue it would of stoped by lowering the boost wouldnt it ?

im not sure if i like the idea of the monitor as it induces paranoia lol
 

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Mine registered around that and holed number 6 piston.

Told over 30 is bad, but the PFC knock sensor may be picking up other noises and giving a false high?

I'd get it checked by a tuner with det cans, or try pulling timng back on PFC, there is a function whereby it will retard ignition by 3 degrees until restarted.
This is quoted from Skyline Australia site:-

"How do I debug knocking, how can I make it go away?
There are 5 methods that come to mind immediately when dealing with knocking and their apporaches are listed below. Before you go ahead and try to be a cowboy fixing knocking if you aren't comfortable etc or don't know what you are doing go and see your tuner. Tell them all the information you have and get it sorted - Don't ignore it or just hope for the best. Either fix it yourself or speak to your tuner.


1. Use temporary IGN adjust
Drive around and replicate the concering knock levels, be sure to note roughly where it happens (rpm or load etc).

SETTING -> INJ/IGN Adjust -> Press DOWN 3 times and you will see -3 for IGN ADJUST. This drops the IGN map 3 degrees timing temporary (will reset when car is powered off).

Drive around and try to replicate the knocking levels again, be sure to try and reproduce the engine load and rpm you did previously. If the knocking has dropped considerably or has gone away completely (very likely) then it is simply a few cells on the IGN map have too much advanced timing.

You should give this information to your tuner;

Max Knock of: 50
At RPM: 4700
At Engine Load: Max Load (throttle was nailed)
Using Fuel: Standard BP Premium
Adjustments: -3 deg IGN timing fixed the problem

The tuner then has enough information to drop onto the IGN map and take out 3 deg timing where 4700 and max load lands on the IGN map. Should take no more than 5 minutes to correct and all be happy. The blanket and braindead approach is to drop the whole map 3 deg either using Datalogit or dialing the crank angle sensor backwards a notch, this is NOT recommended as its braindead. You have stand alone engine management, it should be used like one."

Hope this helps.

Cheers,
 

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Discussion Starter · #3 ·
i think its a noisy engine anyways as when it was mapped its always seen 42, just strange for it suddenly go up to 51. il give tr a ring tmrw and see what they think.
 

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Discussion Starter · #5 ·
well its a good chance its a dodgy bit of fuel which makes sense as its only happened since i filled up. ive been searching and its also been known that it can go haywire when the battery is flat, when i got it out on saturday after 1 month of being stood battery was stone dead and i only charged it for 10 mins just enough to start it and went out for a blast ! so im gonna charge battery and cruise the fuel away and give it beans on some fresh optimax. hopefully all will be good.
 

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yep, hopefully it'll sort itself out. The ignition system (depends on what you've got and if you've modded it) does seem to be sensitive to voltage and amperes available, at least in my car - my car is definitely happiest when the battery is fully charged off a battery tender.

42 does sound like a high base knock level, but I've seen engines that were just noisy, and it could also be your knock sensors - I replaced mine a couple years ago with new ones out of paranoia.

How does your knock graph look like? I always run in trace mode - my engine runs around 10-15 knock in general driving, and hits 25-ish on boost (1.95 bars). But on a really cold start, the whole engine is unhappy and rattling, and I'll see knock up to 30...but the knock graph is flat. Spikes are what you want to look for and worry about.

I agree - the FC Commander does induce a lot of paranoia :p Maybe six months ago, I got a rise in knock by around the same amount, and sweated it for a couple months. It's gone away at this point.
 

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Discussion Starter · #8 ·
my pfc is the early type and when mapped by a professional listening through headset its dead quiet but pfc is in the 40s.
 

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As soon as I read the first post I instantly thought you'd been unlucky with your last batch of fuel. Fuel starts to deteriorate in as little as two weeks, and you have no way of knowing how long it had been on the forecourt anyway. I'd be very surprised if it didn't sort itself out when you have used it all up and was using fresh fuel again. Was it optimax or supermarket fuel?
 

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Discussion Starter · #10 ·
As soon as I read the first post I instantly thought you'd been unlucky with your last batch of fuel. Fuel starts to deteriorate in as little as two weeks, and you have no way of knowing how long it had been on the forecourt anyway. I'd be very surprised if it didn't sort itself out when you have used it all up and was using fresh fuel again. Was it optimax or supermarket fuel?
optimax as its what i always run and what it was mapped on.
 

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Ok. As it had stood for a month it wasn't the freshest anyway, and who knows how long it was on the forecourt before that.
 

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Discussion Starter · #12 ·
charged the battery up today and happened to look at the fuel filter the top of it was rusty so bin in there a while ! lol

had earls braided hose from main line and clip just snapped when i tried to undo it. if its dry, fresh petrol at the weekend and see what she does. :)
 

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Discussion Starter · #13 ·
charged battery and highest was down to 51, new fuel now peaking at 45 max,
 

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Very new to the GTR world (hi :wavey: by the way), but I noticed on my 2nd day of owning the car that the knocks seemed pretty high compared to what I've been reading is normal, while lurking around these forums recently. I think it hit 75 at one point. Another worrying thing was that the water temp was extra high (between 95 and 105, peaking at 115 at one point!)

Turned out, it just needed a few litres or water in it, must be a leak somewhere, although level hasn't dropped since, temp now at a steady 70deg in any condition, but interestingly, the knock levels have dropped down also to around the 20-40 mark, even after a heavy right foot moment.

I guess if an engine is running hotter than it should do, then pre detonation is inevitable, but not something I'd ever really noticed in practise until now.
 

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Discussion Starter · #15 ·
got a wideband in now holding 11.3 at wot to the limiter.

noticed 2 hits at 61 knock one was poping on the limiter and the other was coming on boost and it spiked at 1.8 bar ! was proper freezing last night though which i think contributed to a quick high spike of boost. normally spikes 1.6 - 1.7 bar.

i sure shes fine egt is 800c manifold, 11.3 afr, 14.9 cruising, water and oil temps perfect. took my mate out last night and hes had his share of cosworths, turbo supra, m3 evo etc and he was shocked. hes driven a 500 hp cosworth but he said it didnt pin him in the seat as hard as the gtr did.
 

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sometimes a car needs to sort of "clear its throat" - my engine used to need to boost a couple times before the knock graph would settle down. But it looks like your map probably wasn't prepared for the extra air getting crammed in.

11.3 is a good place to be. I like 11.5, there's more power there, but the margin for error or mishaps narrows the closer you get to 12.

I recently got burned with a bad batch of fuel (gas station selling 94RON out of their 100RON pump) and hit clear-cut detonation (boost kicks in then knock spikes from 18 to 90). Purged that fuel and went to my trusted station, but I still feel that this isn't a lucky month to push things, so I've pulled 4 degrees timing, reduced boost to around 1.75 bars and I'm down at 10.8 with fueling. Feels a bit sluggish, but that's relative - still far more power than is needed for the road!
 

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Discussion Starter · #17 ·
sometimes a car needs to sort of "clear its throat" - my engine used to need to boost a couple times before the knock graph would settle down. But it looks like your map probably wasn't prepared for the extra air getting crammed in.

11.3 is a good place to be. I like 11.5, there's more power there, but the margin for error or mishaps narrows the closer you get to 12.

I recently got burned with a bad batch of fuel (gas station selling 94RON out of their 100RON pump) and hit clear-cut detonation (boost kicks in then knock spikes from 18 to 90). Purged that fuel and went to my trusted station, but I still feel that this isn't a lucky month to push things, so I've pulled 4 degrees timing, reduced boost to around 1.75 bars and I'm down at 10.8 with fueling. Feels a bit sluggish, but that's relative - still far more power than is needed for the road!
quite possible once that had cleared done a good 15 0 - 140 runs and knock was 44 which is **** on to when it was mapped.

need a decent oil pressure gauge next shows 2.5 idle and 5+ above 4k revs on standard gauge but i dont trust it, lastnight i was driving and it went down to 1 bar at idle then shot up on its own. and they are slow to react to pressure change so thats next gauge i will get.
 
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