EriCS

iTrader: (9)

How necessary is it to leave a low octane map? It seems alot of tuners are not rescaling the low octane maps they are duplicating them the two. Whats the reason for this? Is it a better idea just do retard the timing by 3 degrees and drop the afr's down a whole number instead of not having one? Does doing this effect the high octane map?

Wht9er

iTrader: (20)

the reason for the low octane ignition map is to protect your motor. when you get 2 to 3 counts of knock your ecu resorts to the low octane map and pulls timing. the reason for duplicating the two maps is prevent timing from being pulled under "false" knock. this way you don't feel like u hit a brick wall if your ecu picks up knock counts. but at the same time your motor is no longer protected :/

arghx7

The ECU interpolates between the two maps based on the level of knock detected. I don't agree with setting the high and low octane maps to be equal. If false knock is the issue, adjust the knock sensor sensitivity.

hediki12

my hi oct and low oct afr maps are the same ..reason being that i dont want it fluctuating. it becomes a pain to tune and just power loss. my low oct ignition is -3* every were . but i mite change that to 1. because i noticed it switches maps on a 1 count of knock... very anoying.

EriCS

iTrader: (9)

Okay but isn't this there to protect your motor? I didn't realize it switches just off of 1 count of knock? Are most guys running a low octane map or do they just copy the high octane and leave it?

hediki12

yea its there to protect the motor, by stoping the knock. as you may know there are a few ways to prevent/eliminate knock. richen it up, pull timing, lower boost, more efficient i/c. ect ect. the only two things the ecu has controll over is afr and timing . so it uses both to eliminate knock. ive never logged it follow the map of the low oct afr on a 1knock count. but i have seen irregular afr prior to me setting it the same when knock comes in. any knock will drop the octane value (wich is loggable) below 100 at that point it will run on low oct maps or interpolate between high and low. some one correct me if i have that wrong.

EriCS

iTrader: (9)

Well it must be better to have that lower octane map than nothing I am assuming. How else is the eco going to richen AFR's or pull timing? I mean if the ecu is interpolating the two maps then it must be doing its job??? Correct me if I am wrong! I am going to see my tuner in a few I will ask his opninion.

l2r99gst

iTrader: (2)

It still seems as if a number of people don't understand the use of the low/high octane maps and knock.

If the low/high maps are the same, the ECU will still pull timing when you knock. It's roughly 1* of timing for every 3 knock counts. That algorithm has nothing to do with your high/low maps. You can think of that as your short term knock trim, if you'd like.

The high/low maps come into play for sustained levels of high knock activity. You can think of them as your long term knock trims. The exact knock counts are in several threads on the subject, but IIRC, a knock count of 6+ will begin lowering the octane number. The octane number is the factor that the ECU uses to interploate between the high/low maps. So, octane=100, you are 100% on the high map. Octane number = 50, you are exactly in between the two maps, and so on.

Now, should you use your low octane maps? I would say yes, but that's just my opinion. But, they are there for a reason. If your car is consistently knocking, then something is wrong. So, you may as well give the ECU a chance to use a lower map to correct the problem. Otherwise, it will have to use it's short terms algorithm to correct for the knock that is already happening. If you knock counts come back down, then octane number will raise again and put you back on your high maps.

hediki12

+1
thnx for the in debt clarification