Originally Posted by Raptord

but it could definitely stand to be smoother.

Originally Posted by chetrickerman

All evo's I tune, I run the low octane timing map the same as the high octane. Reason is, because the ECU uses an algorithm when reducing timing when knock occurs, in which it takes into account the difference between the high oct and low oct map at that load and rpm, then applies that value into the knock algorithm.

So say just for example, you have 4* of difference between the 2 maps, and you get 5 counts of knock. The ECU may pull 2 or 3 degrees because of the .33* it drops per knock count, as well as overcompensating because the 4* difference between the maps. Now dropping that 3 degrees may cause more knock, and I goes into a kind of downward spiral.

Now if you don't have any difference between the 2 maps, the ECU will still pull 1* for every 3 knock counts, but it won't overcompensate or round up. If you get 5 counts, the ECU may only pull 1*, then it will check to see if that eliminated the knock (which most times it does), then bring the timing back up that 1* the next cycle.

Hopefull this all makes sense.

I use this with great results.

Originally Posted by Ian0611

Chetrickerman (or anyone else) let me know if you can explain this- The graph below is from runs yesterday and today. Same stretch of road and weather was pretty much the same as well. The only change between the two runs is that I did what you said above for today's run. I modified the low oct. fuel and timing maps to be the same as the high oct. maps. Prior to that I was running the low oct. timing map 3* less than the high oct. map and the low oct. fuel map was about .5 richer. Unfortunately I forgot to log boost for yesterdays run but boost went up about 1 psi throughout the entire rev range and peak boost almost 2 psi higher, even though I made no changes to the boost tables.

I never would have guessed that such a minor change would have such a large effect. I need to do a few more runs to verify results, but the mere change in boost kinda has me baffeled. Good luck explaining this one

Originally Posted by Raptord

Are the timing curves in both logs similar?

Originally Posted by Ian0611

Chetrickerman (or anyone else) let me know if you can explain this- The graph below is from runs yesterday and today. Same stretch of road and weather was pretty much the same as well. The only change between the two runs is that I did what you said above for today's run. I modified the low oct. fuel and timing maps to be the same as the high oct. maps. Prior to that I was running the low oct. timing map 3* less than the high oct. map and the low oct. fuel map was about .5 richer. Unfortunately I forgot to log boost for yesterdays run but boost went up about 1 psi throughout the entire rev range and peak boost almost 2 psi higher, even though I made no changes to the boost tables.

I never would have guessed that such a minor change would have such a large effect. I need to do a few more runs to verify results, but the mere change in boost kinda has me baffeled. Good luck explaining this one

Originally Posted by chetrickerman

Like I said. When the high and low timing maps are the same (doing this with the fuel maps doesn't really have the same effect) the ECU doesn't do a "downward" spiral of timing reduction upon the event of knock. Putting the maps the same minimizes the amount of timing pulled per count of knock, rather than maximizing it (which makes sense as OEM engineers think that less timing = less chance of knock). Well with our modified engines, that isnt necessarily the case. In most cases, only 1 or 2 degrees of timing needs to be pulled to eliminate the knock. Pulling too much timing can also cause knock, just like too much fuel, or too little fuel will cause knock.

Im not like Tephra or MrFred that uses ECU dissasembly to confirm this (their work is immensely appreciated), but as I and tephra have found out, the ECU does not always do what the programming says to do.

I have used this method on numerous Evo's that I have tuned, and the end result is always the same. In most cases, the less timing pulled the better.

Originally Posted by Ian0611

Timing seems to have stayed the same. What I don't understand is why boost changed at all.

Originally Posted by chetrickerman

Like I said. When the high and low timing maps are the same (doing this with the fuel maps doesn't really have the same effect) the ECU doesn't do a "downward" spiral of timing reduction upon the event of knock.

Originally Posted by killerpenguin21

so it looks like this may have been my issue.

i did a test tonight with the new low octane maps i made (high octane map minus 3 degrees above 140 load). result was no knock like the old logs (above 6800), and in fact no knock abover 5k. 4th gear came back very clean also. i got a tad of knock at peak torque since it was cold out and i went very right on the load scale. it was about 50 degrees out tonight with 75% humidity. ill have to keep testing this map in the warm.

next step is ecu boost/boost by gear since i was over boosting in 5th down the front stretch last weekend.

Originally Posted by Blitz

I apologize for posting this here but I wasn't about to start my own thread and this thread seems to be full of smart people.



This is from the "How to tune an Evo" thread. What program is this from/how do I view my logs in this format? I want to be able to view my timing/AFR/boost on a load vs RPM grid like this.

Also, for this purpose, is logging 1byte load sufficient or should I be logging 2byteload or loadcalc instead?

Thanks guys.