2015 FRS Tuning or Mechanical Issue

[KxngCorey]

Hey everyone,

I’m running a built FA20 with IAG 800 heads and block. The car is currently tuned for 8-9 lbs of boost and runs perfectly under boost, with clean AFRs. However, I’ve run into a misfire issue that only happens at idle and has been getting worse with colder temperatures here in NY.

During the summer, I’d occasionally get a misfire code that would either resolve itself or I’d clear it. I wasn’t too concerned since the car otherwise ran fine. But now that temperatures have dropped, I’m consistently getting a random misfire code and a cylinder 3 misfire code.

Here’s what I’ve done so far:

Sent both the direct injectors and port injectors out for testing (both checked out fine)
Replaced the spark plugs (even though the engine only has 3k miles on it)
Replaced all the coil packs
Performed a compression test (results were 150 across the board)
The car is running a stock fuel pump, 700cc DeatschWerks injectors, and a flex-fuel kit. The misfires only happen at idle and seem tied to colder weather: at 45°F today, there were minimal misfires in the logs, but last night at 32°F, the cylinder 3 misfire count climbed to 33.

I’m leaning toward this being temperature-related or influenced by oil temps, but I’m open to other ideas. Am I missing something? Or could someone take a look at my logs? Any advice would be appreciated!

[callisto]

What ECU base does your tune use? (ZA1Jxxxx)

[KxngCorey]

Originally Posted by callisto

What ECU base does your tune use? (ZA1Jxxxx)

CalID Shows :ZA1JD00C. no idea if this is the base tho.

[KxngCorey]

Or maybe i can tag in @tomm.brz

[tomm.brz]

well post logs from datazap.me

is it happening at cold idle or hot idle? which spark plugs do you have (grade of them)
as you ask here for help I assume you tuned by yourself ?

[KxngCorey]

Originally Posted by tomm.brz

well post logs from datazap.me

is it happening at cold idle or hot idle? which spark plugs do you have (grade of them)
as you ask here for help I assume you tuned by yourself ?

Cold and hot idle. but impossible to replicate. Oem Denso plugs and no not tuned by myself

https://datazap.me/u/kxngcorey/1325-...data=21&mark=0

[blsfrs]

May not be related, but I've read where a lightweight flywheel can cause misfires at idle.

[tomm.brz]

tune is atrocious
way off, looks like a canned tune with bad values
dont see the clean AFR you re saying
I think it s too lean idling and too rich on high load, both not good for burning ethanol .also way too much ignition timing on idle
does it throw misfires even using petrol? could be too as tune looks bad and I blame it for the misfiring

[KxngCorey]

Originally Posted by blsfrs

May not be related, but I've read where a lightweight flywheel can cause misfires at idle.

I've heard that too but the weird thing is that it's intermittent. I went all day yesterday without it. It was warmer yesterday. Later on in the night it got cold and by the time I got home it was back to missing again

Sent from my SM-S928U using Tapatalk

[KxngCorey]

Originally Posted by tomm.brz

tune is atrocious
way off, looks like a canned tune with bad values
dont see the clean AFR you re saying
I think it s too lean idling and too rich on high load, both not good for burning ethanol .also way too much ignition timing on idle
does it throw misfires even using petrol? could be too as tune looks bad and I blame it for the misfiring

Yes it missfires on both E and 93

[tomm.brz]

i think a combination of cold weather, high ethanol and tune doing too much adjustment during idle mostly
your flexfuel device says e68 but compensation against ethanol is way off on your tune, or maf scaling and speed density are, or both
anyway you arein excess of 20% of fuel , during idle and closed loop ecu is pulling fuel -20% then on open loop just goes full bog rich
on idle both fuel trims and ignition timing trims amply oscillate, i think this + weather, high vacuum, high ethanol are the cause , tune would need a bit of adjustment

[tomm.brz]

things i still don t get:
has it ever run ok? or does it run like always but you sometimes get misfire dtc?
i'd need some more info about how it was before this log you posted
if before was running ok and fuel trims were properly tuned and now they are -20% , something happened for sure
In my previous posts i'm assuming car is good and no mechanical issue actually
Do you have previous logs?

[callisto]

Aside - I was curious and dug into D00C; at first glance, it only has 6 idle speed target tables versus 12 in K00G, but for those 6, they're the exact same from -40C..90C clear through U01A, so there wasn't any sort of obvious cold idle fix in those at least. It looks old enough to be from before the idle stability recall/fixes. There *are* notable -40C..90C changes between K00G and U01A in Idle Speed H and I, and I found a defect in the K00G definitions along the way, but none of this is going to help the problems OP is having so I'll stop there.

[tomm.brz]

can u tell me more about what you ve found for K00G as it s my calid
but you re talking about rom raider definitios maybe? or ecutek also