I5 Spart table selection

[stocker2]

I've been doing analysis of my engine using the scanner and apparently it only use the high octane table. I have a full tank of 87 in there and the advance matches up almost perfectly with the high octane table, there is very little knock retard too and what little is there seems to be totally random (like after a let off the get I get KR, but not when it's mashed).
I suppose it's good that if it can run that timing on 87 I have a lot of room to work with if I put 93 in there. I would just like the low octane table to work when I actually have low octane in there.

[toyoguru]

I would just copy the high octane table to the low octane table, and then throw in a little advance on the high table. Then you can log the KR and see how everything does. Im still in the process of pinpointing what causes the random KR that these trucks have. I havent had time in the past couple weeks to really get into it, so hopefully I will be able to this weekend.

[stocker2]

There's no point for me to do anything to the low octane table. I'm using the high octane table, even with 87. This is the problem, I would like it so it would use the low octane table with 87 and high octane with 93.

I am running 93 and have been adding timing below 2500 rpm and a little above 4000 rpm. I seem to be noticing a difference (I've added 3-5 degrees). The truck seems to take off somewhat faster in second (less boggy) than before and I saying this with the 100 degree temps outside.

As far as knock retard goes, I have noticed most of it in throttle transitions. Such as going from 30 MAP to 95 MAP in a 1/4 second. I have wondered how well controlled the actual in-cylinder A/F ratio is. I made a PID correlating A/F ratio to millisecond pulse width, it seems the A/F would routinely bounce between 14:1 and 15.3:1. At 14:1 or so is the A/F ratio most suseptable to knock.

[colosport]

try messing with your burst knock tables for the random knock. EC suggested that to me and it's helped out alot.

[Shifted]

Well...

The High Octane table doesn't have anything to do with the octane gas in your tank. The ECU favors the high octane table when the vehicle doesn't encounter any knock. When it encounters knock, it "learns" towards the low octane table. There is no octane sensor, so there is no way for the engine to know which octane you have in the tank.

[stocker2]

Well...

The High Octane table doesn't have anything to do with the octane gas in your tank. The ECU favors the high octane table when the vehicle doesn't encounter any knock. When it encounters knock, it "learns" towards the low octane table. There is no octane sensor, so there is no way for the engine to know which octane you have in the tank.

Great!! That's the kind of information I was looking for. It also means the I-5 has more potential since it is NOT tuned to utilize higher octane gasoline. Oh, and It has been in the upper 90s and still very very rarely engage knock retard on a stock high octane table with a full tank of 87.