Gernby

Even though I have a mostly stock '08 AP2, with just a PWJDM intake and custom exhaust, my OEM injectors were hitting 98% duty cycle at 8500 RPMs, so I replaced them with 630cc Siemens Deka injectors. I picked those injectors primarily because I found a decent deal on them used. I also wanted to try e85, so I wanted injectors that would be large enough for that too. However, I was disappointed at how rough my idle was after installing and tuning for them.

The issue was that the minimum pulse width of the 630cc Deka injectors is slightly above the pulse width required at idle. This means that while the engine is idling, the injectors deliver an inconsistent quantity of fuel, which forces the ECU to make large changes in the STFT while trying to maintain the target idle speed and AFR. This also caused the ECU to throw misfire codes frequently, which I eventually learned to ignore.

Over the past few months, I discovered some things I could do with the FlashPro that would improve the situation, and figured I'd share them. First, I found that increasing my idle speed to ~1100 RPMs helped. Second, I altered the Knock Ignition Limit Low table for the cells related to idle (low load / low RPM) so that that the ECU would be forced to retard timing at idle. Before adjusting this table, the ignition timing would sit around 5 degrees advance with a rough idle. However, if I set the ignition limit equal to -1 * the value in the ignition table (i.e. ignition table = 25 degrees and knock ignition limit low table = -25 degrees), then the ignition timing at idle would be 0 degrees, and the idle would be perfectly smooth.

The cool thing is that you can do this while live tuning, so that you find right where it needs to be. See below.

b.r.i.a.n.

your ignition timing at idle was high to begin with. i would've left the knock ignition limit table alone and just adjusted the main fuel table. iirc these motors stock idle at 5 degree btdc. i have mine idling at 7 degrees and it idles perfect. i don't know why these injectors are giving you so many problems at idle. they're really not that big. i've had issues with injectors idling at stoich afr's but i'm talking about 1000cc+ injectors on pump gas. maybe those siemens deka injectors just suck lol.

Gernby

The Siemens Deka injectors probably aren't in the same league as the ID's, but I did get a few unexpected ft-lbs of torque across the whole rev range when I swapped out my OEM injectors. That was enough for me to stick with them.

I agree that the ignition values you see in the screen shot appear to be very high, but those values are almost identical to stock. Even with the values in that table being much higher than 5 degrees, the actual IGN at idle was about 5 degrees. The ECU basically uses whatever value it wants, as long as it falls within the limits of the range defined by all of the ignition tables (ignition low, ignition limit low, ignition compensation tables, etc.)