Yeah octane rating is to tell you how much interpolation the ecu is doing between the high and low fuel and timing maps. a value of 100 means its full on the high octane maps. If it at 90 then thats means 90% high octane and `10% low octane. So if your high octane shows 20 degrees in the high map and 10 degrees in the low map It will take 10% of the difference (that being 10 degrees in this case) so it would drop your timing from 20 to 19 plus 1 degrees for every 3 counts its seeing of knock. If you have both high and low the same then it will be interpolating 20 degrees in the high and 20 degrees in the low so there is no difference and the only timing changes will be from ecu retarding for knock.

 

alright. well also i flashed a modified stock rom today and had basically no knock... we have a lot of different sensors then the evo and i think we need specific settings for them specifically the knock sensor....

i get so much knock around 3k on the tephra rom as where i get none on the stock rom and same timing :l

 

You need to think of the knock sensor as less of an indicator of damage and more like it just another sensor.

The evo and lancer knock sensors are different parts numbers but this will not matter to the rom. The rom simply looks at the voltage produced by the knock sensor and this could mean one of two things about your 4g94 OHC engines.

1) They are noisier than the evo's
2) The knock sensor is dampened on the evo's thus more sensitive settings.


The solution would be to adjust the knock sensor so you don't get knock flash at the 3k mark. You need to adjust the low rpm knock sensor multiplier to be higher so its less sensitive I think your lancer knock setting is like 15 while the evo is like 12 or something along that line.

Once you achieve identical behavior you can trust your knock sensor as the warning light again.

 

Thats an interesting point. Never thought about flashing in a lancer rom and logging the knock using the same timing map as I have now and using that as a guide to adjusting the knock settings in the evo rom.

 

I tried it, it sucks, the lancer rom knock sensor goes "BLINK BLINK BLINK BLINK" constantly, knocksums of 6 or more cruising, it's much quieter at WOT though. I really do hate the knock sensor. The ultimate solution would be to log knock volt, use "det cans", and correlate the 2 so that when you hear actual knock in the det cans, the sensor blips.

 

Which would be a PITA lol. The more I think about it I wouldnt be able to properly put my timing into a lancer map anyways since I see 210+ loads my timing jumps between cells would be crazy big.

On another note changing my fuel map around has helped alot towards getting my afrs in check from prespool to spoolup to full spool and beyond. Made a few adjustments and almost there, then I will be adjusting my timing to match. Went back up to 14 psi while I was at it so I dont have to adjust again. In the process my damn coupler connecting my turbo to my licp ripped AGAIN :-/. Looking into replacing the whole licp setup to take care of this issue once and for all. BTW never use home depot rubber reducers in the plumbing section to build on the post turbo side lol.

 

im pretty sure making the multiplier higher would increase sensitivity no?

also what about the knock sensor filter maps? i see them in my stock rom but not the tephra.....

 

No, the higher the number the less sensitive the sensor is. I can positively say this for sure since I have fiddled with this in the past trying to get rid of my false knock which helped me alot.

 

yeah your right just tried it. and what about the knock sensor filter maps??

 

Dunno there however if you haven't already download merlins tuning guide its awesome!!! Just read a nice description of knock and how the ecu determines the knocksum. It also explains how you can determine if your knock is real or fake and how to safely tune it out. Honestly I don't know why I never just read this thing front to back in the beginning.

 

So for those of you running the evo 8 16g turbo can you guys tell me the size of your outlet on the j pipe? Starting to wonder what is going on cause mine comes off the turbo then expands to 2", however the piping I have is for 1.5" hence why I have had to use a 2" to 1.5" reducer. I have been searching and ALL the turbos in the FS section that have pics seem to have the smaller 1.5" outlet. Anyone know where this J pipe I have may have came from? It was the one shipped with my turbo. Anybody have a spare evo 8 j pipe they would like to sell me with the correct diameter

Here is the size difference.



And here is a pic of the expanded j pipe

 

I guess that part is somewhat confusing but as pointed out earlier no its less sensitive the higher it is I'll explain.

To put it in the most simple terms the knock sum runs off an equation which is something like RPM * load * constant * multiplier = max volts before knock. This is an analogy but you grasp the idea?

So the higher the multiplier is the higher the knock voltage can go before "knock" is incremented to the knock sum counter. The lower and the less voltage it would take to see knock sums increase. True knock is a pretty radical spike in voltage so your pretty safe jumping up the voltage multiplier in most cases.

You can graph knock voltages and if you see a really large jump in volts, saying your lucky enough to see that spike sometimes they change before it can be logged, you can correlate real knock to the multiplier.

 

Lance you can purchase a lower intercooler pipe thats not 2" all the way through you know?

If you don't want that get the extended j pipe so you can just use a 1.5 to 2 coupler.

 

Just really perked my curiosity after looking at all those turbos in the FS section and not a one has a j pipe like mine. I seen a coupler I can use on siliconeintakes.com. Just annoyed atm more than anything I have been under my car or doing something to it every day for like the past 2 months and not getting very far. Just my ranting I guess

 

I feel your pain man, frustrating is the road to reliable boost

About those knock sensor filter maps....not knock maps at all, they are actually misfire detection maps, so don't mess with them....they were mis-defined in the beginning and are now known not to be knock related at all.