Razor2001

Hi all,

After reading more and more I am coming to realize that bhp and torque is not purely dependant on boost but timing snd knock correction as well. I guess the cooler, safer, higher octane etc can give you more power via timing. i.e same exact turbo car etc etc but one car is running 25 advance timing and +8 correction will be faster than a car running the same boost but lower timing and knock correction figures.

I was curious about what timing I should be running and what is considerd good etc.

I have a JDM STI-7, full turbo back decat (scoobysport) EcuTek via mail ecu remmap by ScoobySport....I love it I am running about 1.3 bar peak tappering to about 1.1 - 1 bar redline, slightly varies per gear obviously.

On WOT in any gear I usually see between 20 to 30 advance on the ignition timing and between 5 to 12 positive knock correction, never see any negative.

It obviously varies depending on the rpm level but I would guess that avg. is 25 ignition timing and 9 positive knock correction.

Do the above figures look like everything is safe and well ?

I got the figures from an EcuTek delta dash on multiple runs so they should be fairly accurate.

If I added lets say race 116 octane fuel for 1/4 mile runs would the ecu take advantage of that in a few miles and increase timing even more or will it just give me a greater safety margin and the only way to really get a benefit from the race fuel is to run more boost as well ?

What happens after the 1/4 mile day and I go back to regular 98 ron gas (car has been mapped fpr 98 ron). Do I need to do a ecu reset or will it learn t quick enough to not run too much advance and cuase knock / det ?

Anyone else have similar findings on their JDM STI-7 or UK STI 7 as far as ignition timing etc ?

Thanks guys and sorry for the long post

Cheers,
Ray

aus73

Ray,

We have looked very closely at what the standard ecu does with ignition timing and the knock correction system. When we have been doing engine development we run a pressure sensor in the combustion chamber to monitor cylinder pressure - which is a more accurate way of detecting detonation than the traditional knock sensor. We've found the ecu does take a while to learn when a change to a higher octane fuel type has occurred. The knock correction values are determined after the engine has gone through the rev range.

I'm not sure whether the standard knock control system relies solely on frequency measurment, or whether they run a more sophisticted system where the spark plugs are fired twice and resistance measurements are take across the plug to determine detonation - probably the first option. Whatever the case, the knock correction value appears to be what the system thinks it can advance the timing by at those points. This has proven to be incorrect - as the engine will start to detonate when the values reach 2 and sometimes 3 - we've never seen negative numbers. The system seems happiest when the knock correction values are around 5 degrees.

9 degrees is quite safe - but its what you would expect from an ecu map that is not tuned to your specific car. Hope this helps.

Chris Davies
G-Force Motorsport

mutant_matt

Ray,

You might also want to ask this question on the Ecutek forums as you may get a more specific answer (possibly) as Stephen posts on there and he has a very good understanding of exactly how the Subaru ECU works (not surprisingly).

Hopefully, also Pat and Pete can offer some specific advice knowing your map....

Matt

Adam M

who is pete?

Pete Croney

Hi Ray

The Denso ECU lets us determine a base ignition map and a correction map. The correction map is something that the ECU builds itself, based on the knock sensor readings. Our input to this map is to limit how much advance it can add. Whilst the ECU should always add a safe figure, it can get itself into problems if too much advance is allowed. If, for example, it was adding +20 at 2750 but could only add +11 at 3600 then a map with such wide correction potential gives uneven running and can give rise to det. Also if a massive amount of correction is allowed then the ECU tries to use it all and this can give the occasional pink on the knock sensor. I suspect that the ECU tries to use some smoothing of the values and this may be fine with the standard correction table but does not work when things are pushed further.

The ECU rebuilds these tables permanently and changing between fuels should not be a problem, but it will take approx 150-200 miles before the new table is fully built.

Adam M

ahhh, that pete!

Bob Rawle

The knock correction numbers themselves are meaningless unless you relate them to the actual base map settings. 9 degrees could generate bad det on the wrong base map. Razor do you know wether your base ign map is std or modified? What advance multiplier are you running and what does the knock correction table look like ... woops sorry that's only available through Flash2002 !! If you have DD though you can read the advance multiplier. Also what version ecu code are you using.

Reliance on the ecu's ability to react to det is to be avoided at certain areas of the rev band, as sometimes it completely misses the plot !! (in both directions)

The ecu actually learns very quickly, its possible to get the ecu to adjust its advance multiplier within a few hundred meters and sort out its correction table to 80% in less than 1 mile. Just depends how you "teach it" If you go up in fuel ron though I would reset it and teach it again, you will get a better result. When you go back suggest you reset and re-teach otherwise it will det for a short while while it learns, and could knock itself down too far again giving a lesser result. You shouldn't damage anything in doing that though as its far keener to pull back compared to advance up. (normally)

cheers

bob

Razor2001

Thanks for all the posts guys !

ScoobySport did the remmap and I have no idea what the 'multiplier is etc '

I will try looking for it when I do another DD log.

Is it possible to hear det using det can etc if I had them to my ears and someone was driving my car or can it only be done at a dyno ? Would I even know what to listen for or is that something the pros would have to hear...basically should I get det cans and if yes, from where ?

Cheers,
Ray

john banks

Easiest thing in your situation might be to fit a knocklink. It works pretty well with standard engine internals, and tends to be on the safe side if you leave the sensitivity on maximum. It is easier to describe the number and colours of LEDs you see rather than noises you may hear.

Bob Rawle

Det would be heard clearly IF the det cans are the right configuration, Johns suggestion of a knocklink is sound but you do need to correlate actual det to the lights to ensure that paranoia doesn't set in.

bob

Razor2001

Wish I had a good tuner locally....I would be they don't even know what det cans are here.....I am thinking I will just have to go with a knock link and leave it at that....

Besides Pete and Pat gave me a safe map and I have should have no worried

Wish me luck !
Cheers,
Ray

Absolute Shower

What does det sound like with det cans? I'm reading upto 14 deg + knock correction with upto 1.6 bar and the knocklink doesn't light up (maybe upto two greens at times) but I do 'ear mechanical noise which is constant at high rpm (5,000 +).

Is det a non-constant sound? I've heard a car (not Scoob) det before but under light load in high gear...but my motor makes loads of noise when driving wild so can't hear normal engine noise unless through det cans which sounds different.