Spark threshold and knock

[AVP]

Hello,

i wanted to ask this query i have just to rest my mind really,or to understand things a bit better.

I have been getting some funny sounds from the engine,only on 6th gear pulls,something that i had with motronic as well, which sound as loud 'tsk-tsk' sounds,happening rapidly during hard acceleration. The car with both ECUs was running fine and pulling hard without any weird EGT indications either during these acceleration incidents and there are no other signs of anything being wrong other than those sounds im describing.

Now these are quite distinct and loud,it is not like you would need headphones to hear them or they are mumbled through interference or anything,so im wondering if these are really knocks or something else,since to my understanding,if knock was to be that loud,it would be more or less devastating for the engine anyway, isnt that right?
Also a knock sensor should be able to pick up something that is so loud in pitch the driver can actually hear it clearly as well!!

I will try and make a sound file too

My spark settings on those rev range that i have heard this is about 16-17deg, on boost of 300kpa and as i said,this is only happening on 6th gear pulls.Also im always using 70:30 water/meth injection along with BP97octane fuel, which makes me think that this should not be knock related.

can someone please tell me if knock can actually be that loud and have all those secondary corresponding symptoms?

I have made a few changes on the spark table,and lamda table just adding a bit more fuel on that region.The problem is that when i do that,and have get lamda richer, i sometimes get too rich on 3d gear and the car stumbles,while it is ok for 4th gear and above pulls.

lamda on the pulls was: 0.88 to 0.84 on the 3000-4000rpm region i did the test

thanks

vasilis

[gunni]

You only have 0.88-0.84 at 300kpa?

I´d not run it leaner then 0.8

Also, that is very likely knock/det/ping. Check your Manifold temps as I´m sure during the 6th gear pull they are higher then the 3rd or 4th gear pulls.

Your running MAT dependend retard I´m sure? It may not be enough, the latest firmware has tables for this where you can retard the ignition more then has been the norm as the intake temps go higher. Thus allowing you to create a better safety net.

[AVP]

on the 2500-3000rpm area i have that lamda,because when i was on 3d or 4th gear, it was getting too rich and was couphing.After that it goes to 0.80 and finally to 0.75lamda as revs go higher. EGTs are about 800-850 on 3000rpm and do not go more than 930 towards the higher revs (i havent tried 6th gear pulls anyway more than 5000rpm though but on 5th gear pulls it stays low).EGT is on the turbo hotside.

My inlet manifold temps are no more than 20 to 30C and that is because after 1bar of boost the water/meth injection comes in and keeps everything nice and cold( i havent checked them during pulls and i will try to). The 1.1.27 version has the mat retard implemented which at those inlet temperatures is supposed to keep the degrees of advance at about -1degree of timing than the setted one.


Im waiting for an official 1.1.5x version from VEMS that would allow that.

Here is the thing. ON 3d gear and 4th gear, i get the turbo spooling at around 3500 and 3200rpm but on 6th i get it from 2700rpm.

when i build the maps, if i run 0.80lamda from 2500(so as to cover the 6th gear area), the car goes rich on a 3d gear WOT from low rpm and stumbles,but obviously runs ok on 5th and 6th gear.

If i do the other way around and make that area leaner,then i risk to have detonation on 5th and 6th gear. As it is now, it seems that i only get that with 6th gear only,so i will try and richen things there as well.

Could i also be getting knock if the advance is too low? does 14 to 16deg sound low to you?

[gunni]

14-16 does sound high for 300kpa. but it´s pretty hard to say. As engines can be so different.


Can you log the 3rd gear pull against 6th gear pull. Maybe there is a chance of adjusting the rpm range there so to tune out
the problem. I´d be interested in looking over the log.

[AVP]

i will log a few pulls now.

i will also lower the deg.of advance on the time that turbo sets in as well.I have lower timing there and gradually but slowly bring it higher as revs go up. I have noticed that as i rise the advance slowly i get better EGTs as well,which makes me thing im safer on higher revs.Also it is richer there anyway.

I have altered the fueling on that initial area of revs and see what will happen.

[AVP]

here are my current spark and lamda tables,with the alterations that i have done

[gunni]

What about the fuel map.

[AVP]

fueling map is close to the lamda and on the rich side on the top bins.I use EGO correction closed loop with 15% +/-

[gunni]

That doesn´t matter,
I need to see it to make a educated guess on why your engine is over fuelling or under fuelling at various conditions.
As you said it can´t be close to the lambda map if it reacts in two different ways in two sets of gears.

[AVP]

ok here is the fueling map

[gunni]

definitely get a log of both situations,

3rd gear pull from 1500rpm
6th gear pull from 1500rpm

[AVP]

ok
going out now

im going to see if i can do that with ego on and off

[dundersmurfen]

my thought is: ouch way to advanced timing on way too lean. lambda 0.77 and maybe 5 spark advance at 300 kpa even at lower revs, specially less advance 3000-4000

[max]

Offtopic: can someone tell me in few words the difference between VE table and Lambda target table?

[AVP]

i did some runs, and the log files are quite large.After studying them i realised that there are some instants where for some reason for a given VE value (this time it was 99) although most of the times it gives me a value of lamda of 0.78 for example, on a couple of instances it went 0.70 and maybe more, thus making the car run rich.

Now i  dont know why this happens occasionally,although both lamda and VE are supposed to be giving out something different. Im not sure if this lamda value is due to water injection,as the amount im spraying is not that large anyway.

Out of all tests,i managed to get rid of that sound.I have reduced spark to 13+ deg.and i have given more fuel on those areas of highest torgue as well.

I do get however at some point if i go WOT on 6th gear,an either missfire or some kind of rich mixture stumble as the boost needle passes through the 1.5bar area,and as it surpasses it , it stops and car runs fine after that. I have checked and noticed that before,as i made the mixture leaner,this feeling went away and corrected itself.It seems now that it needs finetuning on the 250kpa area to make it work properly