delturcious

iTrader: (4)

I've read all I can and am stumped on this one. I can't get a stable idle with the MS3 when warm even though it was fine with the stock ECU. My car:

• 04 MSM w/ FM intake & ARTech exhaust
• Reverant-built MS-3 basic
• FF 720CC injectors

Idle behavior:

• Follows idle warmup curve until ~130degF
• Stumbles once
• Idle starts oscillating more and more as it gets up to 180F.
• Target 860rpm, range is about 810-900

Basic tune details (and what I've tried)

• EGO correction off (no effect)
• Unplugged IAC valve, opened up TB adjustment screw to manually set ~860rpm target (no effect), and put it all back.
• Manually set all the idle cells to the same value (no effect)
• Car behaved the same way on OEM injectors + MS3.
• Tune is good enough for me to drive around; not good enough to push it or dial it in. AFR targets and ignition timing are a combination of y8s and Braineack tables posted over the years. Next steps are fuel pump, e85, and Vladituning after I figure out the idle.

With IAC closed loop enabled, the valve stays at 52 steps at 860rpm during oscillations. My PWM settings are terrible right now so it takes a loooong time to come back down if I rev up the engine.

Tune and log attached--any thoughts would be greatly appreciated.

HowPrayGame

Pretty sure that's all the Closed-Loop Idle PID gains being off, I was never able to get my idle more stable than the settings my MS3 Basic came with.

500 Slider
25 P
40 I
15 D

Used this on my N/A NB2 and an NA6 with a hot side supercharger, both were rock solid.

In my experience the slider going up made the idle more unstable. Double check your req fuel requirements to ensure its set to 720cc injectors as well just in case. Your dead time table looks correct.

Tuning the min/max values of the IAC Steps will also help with this.

18psi

iTrader: (76)

Timing and fuel will easily cause oscillation even without a valve

delturcious

iTrader: (4)

Thanks for the specific NB2 PID settings--I'll give those a shot in the morning. Frequency is currently at 511Hz. I've certainly tried a lot of different PIDs, but I've changed a lot of other things in the tune since I used Rev's defaults for idle. My dead times were taken from FF, but I rescaled my VE table before I installed the injectors attempting to get more resolution. My Req'd Fuel setting likely won't match anyone else's even with the same injectors.

Oh. Guess I need to do a bit more reading on that front. Or maybe I just need to go ahead and hire you to do all this for me I'm just not driving much during the pandemic, so gathering data will be slow for now.

delturcious

iTrader: (4)

I changed the idle PWM settings to what HowPrayGame suggested as well as knocked timing down in those cells to 11 (from 16; Brain suggested 10-12 in other threads). I also raised fuel in the 6 idle cells and made it a little higher as you move up and right in the VE table. That all seems to have helped some; it's more like ~50 RPM swings now instead of 100. Still not perfect, but certainly better.

18psi

iTrader: (76)

I've found that different cars like different settings. So while it's good to have parameters/thresholds, don't stick to them too strictly, you want the car pulling as much vac as possible, and you want to trigger an afr that makes it happy, it doesn't have to be 14.7 either