low load knock and heat
 

Hi Guys,

I just thought I would say that my low load (50-100load, 2200-2700rpm) intermittent knock has gotten worse with the high heat.

It was 43degC yesterday/today and my knock light has been flashing, especially when going up slight hills.

Time to drop some timing?

Cheers
D.

Just wondering if its real or phantom knock because I get knock in that same range of load/rpm. It happens whether I run pump gas or E85. If you have access to race gas, how about filling up on a tank to see if that kills the knock? If it stops knocking, pull timing. If it keeps knocking, adjust the knock tables. So cool to finally have access to those tables.

mmm.

regular driving = mostly fine, ie 0-50km/h hour type stop/start, occasisonal flash at 2500
freeway driving = more likely to flash, ie constant rpm, then maybe going up a slight hill will cause it to flash.

I don't really want to pull timing if its only a FWY thing, since then my regular driving will be affected...

At the moment I am running on my "race" map, which has lower timing in the pertinent areas but its still a problem (less so thou).

Don't have access to race gas, I could probably put some oct-booster in thou...

+1 about the knock maps, BUT I want to confirm its phantom vs real first :)

43C is pretty hot. I would rather have that, though, as a week or two back we had a high (yes, a high) of -20C for a day or two.

Anyway, what mrfred suggested about race gas is probably the best way to find out if it's real or phantom knock. Otherwise, just flash in some lower timing numbers and see if it reduces or elimates it. If it stays the same, in the same areas, then it's most likely phantom and could be tuned out with the knock tables.

Dave, we are suffering here with the heat too.... was 47C in the dyno room the other day! What you can do is use the Ignition Trim for Air Temp vs Load map. It is a 2D map where the Load needs to be over a certain amount before the ignition trim will become active. If you are on pump fuel and driving around in the heat wave we are getting things will become very knock prone. Some things you cant really tune for, like the fuel temperature changing in these extremes. If you lower this map the trim will take the timing out at a lower load level. I would not be too concerned about running a few degrees retarded at that rpm. You will find pulling even 3 degrees might only cost you 1kw which you will never notice, so taking 1 degree will be virtually transparent. That failing, you may need to make the Ignition Trim vs Air Temp map a little more aggressive. At least you are seeing extremes and if you can make it run perfect in these conditions you can be confident things will be reliable all of the time in future. You can PM me if you need specific details in setting up for these crazy temps.

mm I was going todo this - but I thought it was based on coolant temp...

will check now :)

Just incase you dont have them...

<table name="Ignition Trim vs Air Temp" category="Timing" address="3c8e" type="2D" level="2" scaling="Enrich">
<table name="Air Temp" address="71ca" type="X Axis" elements="8" scaling="Temp"/>
</table>

<table name="Ignition Trim vs Air Temp Active Above Load" category="Timing" address="3ca8" type="2D" level="2" scaling="Load8">
<table name="Engine Speed" address="6c82" type="X Axis" elements="10" scaling="RPM"/>
</table>

Should be exactly the same in 88580013 and 0015. Can't remember which one you have. :-)
I would guess you already have the Enrich scaling?

Thanks for that Matt, I had managed to loose the Active Above Load parameter somehow.
Sodding hot in Sydney atm, and not going to get better anytime soon.

Hey, try out west where I am. I know Adelaide and Melbourne are copping it, but it was 40C today in the shop, and has been over 38 each day for over a week now, with the weather report saying the next 8 days are the same! I have been not only tuning, but packing up the shop as we move into a larger premises, so I am completely drained tonight!

I think I just found another parameter that goes with these maps. It is untested, but looks to be a coolant temp you need to be above before these trims work. The default is quite low at 30C, at least in my rom.

do you have open air filter?

Possibly too much mivec advance in the low load map area's? My car did this on one of the more advanced mivec maps.

On page 26 of the mivec thread, Jeff Jeske is describing this low load part throttle knock condition.

https://www.evolutionm.net/forums/ec...tuning-26.html

Can't totally confirm this yet but it's appearing as so. I am noticing a drop in low load knock just with leaning the cruise AFR in the effected range (>20% load from 1500 - 3000rpm) beyond stoich (15.0 -16.0 afr). It appears a mild - moderate acceleration from stoichiometric (catalytic range) causes much more knock activity than leaner. Stoich produces the greatest temperater/power ratio. The end gas from this remains when accelerating richer with increasing load along with hot spots, then it pings. The timing and afr can only help to some extent. Running it leaner in the area prior to tip -in has helped.