RickyLee

hello s2ki peeps, i have been reading my OBD datalog, my S2k is NA. No MIL, also jumped wired 4-16 no code found.

i found something funny that my post o2 is reading 0 volt! but my S/L Fuel Trim seems to be legit.
but sometimes Short TFT reads down to -21 gets really rich. Long TFT stays around +8 ~ 0 ~ -0.8 most of the time..

If you look at the IAT seems really high 160F in one of the data file.( ill hondata gasket if i have time to install )

ok so the main concern is
Whenever i start up with warmed up engine, the engine seem to loss power whenever accel.
exhaust pops whenever decel. alot( unlike before).

im sure there is a vacuum leak somewhere, ill be testing with smoke machine soon.
ill also test o2 with dvom.

Data in below
Google Drive Link >HERE<


Ill be uploading more data.

Please help~~ n correct me if im wrong or right.
TY

RickyLee

ap1 NA

yamahaSHO

These cars run off speed density, so a small leak unlikely to affect anything. I found in stock trim, these cars have pretty large swings in fuel trims. I was unimpressed with the stock ECU and [OEM] tuning on these cars, so after trying a Greddy E-manage, I just went to an AEM EMS v2. Any of my near stalling issues that seem common on here went away, instantly... Even before I tuned away from the base map.

IAT's can get high because it's mounted right on the intake manifold and the rate at which change happens is slow. It's likely that this is helping to contribute to these issues. You might want to search for "MAP whack" and see if that helps your problem.

I haven't played with the rear O2 on my car as I don't have one anymore. If it's a 0-1v signal, the 0.xxxV you're seeing in the logs is just fine.

UberDuper

Is it your pre-cat or post-cat sensor that's reading 0v? What's the other sensor showing?
EDIT: Just looked at your data. Not reading 0v at all times. Have you tried a diff sensor? Are the 0v spots just the ECU going open loop during engine braking?

I've been trying to figure out a similar issue for a long while now. Periodically getting extremely rich at low rpm accel and nearly stalling at idle. Only seems to happen after sitting in stop and go traffic for an hour. Get home and park it for a couple days and then it's fine for a day or two and again after the slow commute home it starts again.

RickyLee

thanks for looking guys

pre-cat o2 reads sometimes 0.000v not just 0.1 or 0.2
0.000v is deadly lean.

(opps i typed post o2 lmao)
my data only shows bank 1 s1 there is no s2 (i disabled s2 readings).
there is no post cat readings.

when the engine is warmed up it shows close loop which is good sign.
i'll be reading all of my data this weekend.

my hood can be vented, but i leave it closed because of god damn rain and also i park outside no garage....
if vented my IAT reads really "cool" i havent got a chance to log a data with vented hood. but ill try it.


About the MAP. My MAP is whacked but with or without map whack it has been reading steadily,
i'd love to have an af ECU, but i dont wanna toss my bills away lol.

Dont you think the popping exhaust on decel. is sign of exhaust leak? ( well i have my cat removed )
i found out the smoke was coming from behind the engine( not from the exhaust lol) when i was poring into vac. line with seafoam.
smoke was really thin and it didnt last cuz i ranout of seafoam. i decided to do a check with fog machine.


I have tested my OEM coilpacks and my spark plugs with ohmZ.
believe it or not my S has 170k miles. i have no idea what oe spec. and i dont have denso tech sheet.
coils ohm / spark plugs
1. 49.9k / 48.7k 5.06k
2. 48.8k / 47.5k 4.73k
3. 49.7k / 48.4k 4.75k
4. 49.6k / 48.4k 4.75k

Ima change my coils to ap2(i doubt there will any gains on hp but may be 2torque? lmao )
because Ap1 coils are pricy. and plugs soon.

yamahaSHO

Roger on the typo, I was starting to wonder why I was thinking about the 2nd O2. As for the primary O2, it should be a 0-5v signal and 0v is PIG RICH, not lean.


With that data, I'd personally would be swapping out the O2.

RickyLee

thumbs up, i also think my o2 is sluggish. due to no MIL if it was bad then there should be MIL.
ill enable my obd to retrieve my post o2 readings later
it should read about the same. just to make sure.
if not ill diagnose my pre o2 n my ecu n hopefully it is not ECU or ill be crying LoL.

About the sensor as a noob tech. (me)
i certainly know if the o2 is reading 0v means lean , 1v means rich.

ive been fixing ppls cars for years and ive been looking for a job as entry lvl tech but noone want to hire me :'(
if im wrong about volt reading, maybe thats why shop owners dont want to hire me ;'(

anyway, thanks guys ill update the thread once i get everything fixed
feel free to leave suggestions and comments.

yamahaSHO

RickyLee

ah thats wide band o2
mine is stock uses narrow band o2 lol

RickyLee

i have no engine performance mod
i want a wide band n ballsport or bellsport? header