Jump to content
SAU Community

Recommended Posts

The island im on just changed fuel suppliers what i noticed right away is the fuel is very bad now. What i used to get on 14psi about 47 knock on my power fc is now 114.

Can any one give me some suggestions on how to adjust for this. And is 114 knock very bad.

????? I know the threshold is like 60. Damn im pissed:angry::angry:

Link to comment
https://www.sau.com.au/forums/topic/460487-knock-on-power-fc/
Share on other sites

When you say you used to get 47 knock, do you mean every time you drove the car or thats the max you ever saw?

If you were getting 47 frequently, either there is some Phantom knock being picked up or the tune wasnt the best. If its the later then the slightly worse fuel will be emphasising this

It needs a retune or you need to import good fuel......

  • Like 1

Only all out at 14 psi. With the same conditions its now 114 with the new fuel.

Hmm ill have to return it. For this fuel. Ill pull out the data logger and go at it this week.

One question.

What an acceptable knock level on a power fc all out. Cruisen its like at 3 or 7 the very most.

Thanks again.

No such thing as "an acceptable knock level". The factory sensors are so variable and give false readings (both positive and negative) and the PowerFC implementation isn't that great either. The knock reading on PowerFCs is no substitute for properly listening for knock when tuning, and barely useful as a warning when driving.

  • Like 1

What an acceptable knock level on a power fc all out. Cruisen its like at 3 or 7 the very most.

FWIW my power FC has 0 knock on cruising.. the most i've ever had is like 17 or so, probably get the tune touched up or try a different servo

As mentioned by gtsboy, the powerfc and factory sensors are not exactly the most reliable source of info

Thanks. Guys. So what electronic device do i need to use that can detect knock.

I have heard of a head phone or somthing of the sort. A very long time ago some linked me to a device that looked very good. I just for nothing cant find it. I cant even remember the name. By now it may be out dated or have a newer version.

What do you guys use.

Thanks to all. I will read. Lol GTSBoy it may have been you that post that knock ear up. I remember that. Looks the same. But hiw do i know my limits. If i add more fuel that will be base on my AF'S log looking for 12.0 and if i pull timing whats my limits wit what effects if i over do it. Or how do i know im over doing it. ?? Sorry for the confusion if any guy. Oh i found the haltech knock ears on ebay over here for 860 USD. NOT bad. Well what do i know.

Status i will read thanks

Sadly, the best way to see what changes to mixtures and timing are doing is to tune on a dyno. It's the only way you can see what happens to the torque while listening closely for knock. If you have to do it on the road, it is probably the case that;

  • You won't stop it from knocking by adding more fuel if you're already at 11.5 AFR. That is to say that 11.5 is pretty rich and if you're that rich then more fuel probably won't help. But it is impossible to tell you where the real cut-off point is, because these motors are all a bit different from each other. And that is before you start to factor in the possibility that just one injector might be flowing less than the rest.
  • You can probably lop off 5 degrees from the troublesome parts of the map (just as a wild guess) and see what happens. But of course the more you take off the higher the exhaust temps will go. And you really need to be able to listen for knock properly.
  • Like 1

Hmm. Thanks again. Your suggestion seems to line up with things i found out in the past GTSBoy. The hard way that is. I will order the knock device. But im working very hard on buying a dyno for my shop. Knowing that it wont make me money really. Its all personal. And to add max knock before torque drop off is a big clue. On the haltech knock ears keeping in mind i haven't used it as yet. What is considered an the ceiling level for knock. Thats wouldnt have no affects on softer aluminum head. As all the engine i have so very well blow up i have learnt took its toll on the heads. Pitted and obvious signs of detonation. Damn life of owning a moded skyline is tuff for me.

If you read the thread Trent linked you, you should be able to understand knock fairly well.

Obviously when you tune on a dyno, you don't want to hear any vibrations, 'pinging', knock or whatever you want to call it.

You start off with safe values or a base map and then progressively work until you can't put in more fuel, timing, etc due to knock or limitations from the vehicle.

Takes years of experience to get everything perfect in terms of fueling, timing and many other variables to consider depending on ECU capabilities in such a short time frame.

P.S. The knock ears are kind of useless for road tuning like GTSBoy said, it's best to have knock detection and all the other EGT sensors and what not running on a dyno.

If you are considering doing more work in the future it may be an investment to source a dyno to prevent engine failure.

Sorry to jack the thread, just put a power fc in my 32 with a 25neo in it, did an initialise then did the self learning idle bit... Now when I rev my knock jumps up and ecu goes into limp mode..

So now I can't rev over 2k, are my knock sensors throwing out a fault reading? What do I do?

Edit: just did another initialise and it doesn't limp anymore, but the knock Sensor still jumps around a fair bit, at 4k it'll nearly max out

Edited by Walfers

Can you give more details? What knock values are you getting? Are you running a base map? Do you get any engine check light flashes? What sort of modifications have you got on the car?

Edited by breaker1845

Sorry, saw up to 157 before with revs at 6600rpm. Running the standard map it comes with, no tune. I don't see any flashes as such but some threads say there's a toggle to wether it lights up or not.. If it's the actually engine light on the dash I have a feeling it's been removed because it doesn't come on with just ignition.

Mods wise there isn't a lot going on, stock rb25det neo from a r34, exhaust, fmic, pod and a boost-t.

When I got the car I noticed an odd rattle at around 4.5k that carried for about 500rpm and then stopped, sounded very similar to a sound my mates cat made at idle before he replaced it.

If I take off very slowly I get the same rattle, but only at revs sub >1000. I'm thinking it rattles again and the power fc pics up that noise/vibration? A lot of people are saying it can pick up gear crunches and what not as well..

Never drive an engine on a PowerFC base map for longer than it takes to get it to the tuner.

Rookie error.

+, get it on the dyno, with a tuner who has proper knock listening equipment, and you may stand a chance of finding out what the f**k is going on instead of blindly wondering.

+, get the bloody dashboard out of it and find out if the CEL globe has been removed.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now



  • Similar Content

  • Latest Posts

    • For once a good news  It needed to be adjusted by that one nut and it is ok  At least something was easy But thank you very much for help. But a small issue is now(gearbox) that when the car is stationary you can hear "clinking" from gearbox so some of the bearing is 100% not that happy... It goes away once you push clutch so it is 100% gearbox. Just if you know...what that bearing could be? It sounding like "spun bearing" but it is louder.
    • Yeah, that's fine**. But the numbers you came up with are just wrong. Try it for yourself. Put in any voltage from the possible range and see what result you get. You get nonsense. ** When I say "fine", I mean, it's still shit. The very simple linear formula (slope & intercept) is shit for a sensor with a non-linear response. This is the curve, from your data above. Look at the CURVE! It's only really linear between about 30 and 90 °C. And if you used only that range to define a curve, it would be great. But you would go more and more wrong as you went to higher temps. And that is why the slope & intercept found when you use 50 and 150 as the end points is so bad halfway between those points. The real curve is a long way below the linear curve which just zips straight between the end points, like this one. You could probably use the same slope and a lower intercept, to move that straight line down, and spread the error out. But you would 5-10°C off in a lot of places. You'd need to say what temperature range you really wanted to be most right - say, 100 to 130, and plop the line closest to teh real curve in that region, which would make it quite wrong down at the lower temperatures. Let me just say that HPTuners are not being realistic in only allowing for a simple linear curve. 
    • I feel I should re-iterate. The above picture is the only option available in the software and the blurb from HP Tuners I quoted earlier is the only way to add data to it and that's the description they offer as to how to figure it out. The only fields available is the blank box after (Input/ ) and the box right before = Output. Those are the only numbers that can be entered.
    • No, your formula is arse backwards. Mine is totally different to yours, and is the one I said was bang on at 50 and 150. I'll put your data into Excel (actually it already is, chart it and fit a linear fit to it, aiming to make it evenly wrong across the whole span. But not now. Other things to do first.
    • God damnit. The only option I actually have in the software is the one that is screenshotted. I am glad that I at least got it right... for those two points. Would it actually change anything if I chose/used 80C and 120C as the two points instead? My brain wants to imagine the formula put into HPtuners would be the same equation, otherwise none of this makes sense to me, unless: 1) The formula you put into VCM Scanner/HPTuners is always linear 2) The two points/input pairs are only arbitrary to choose (as the documentation implies) IF the actual scaling of the sensor is linear. then 3) If the scaling is not linear, the two points you choose matter a great deal, because the formula will draw a line between those two points only.
×
×
  • Create New...