a/f command problem
 

So ive been using, logging and tuning on oft since just about when it was released for this car but ive never encountered this problem. I went turbo about 3 months back and put on shivs base map, it seem to run fine and log fine for a while but recently its started to give weird readings while cruising.
On start up the car will only go as high as 14.2 when it should be 14.7, after about 10 min of driving i will notice it creeping richer and richer until its about 12.9 at partial throttle actual af and commanded. around this point the car will little by little stay in closed loop longer and the command will read 15.05 but actual af will be 12s-13s light throttle. During full throttle it sometimes goes to open loop and af actual and command is normally about right. I have no fault codes and no noticed exhaust leaks. I have tried different maps and reflashing it. shiv is leaning towards 02 sensor but id like to know if anyone has some knowledge on this before i drop a couple hundred on a sensor.
this is a pic of it cruising on the highway, fully warmed up.

Don't quote me but isn't the window our ECU see fairly small? I didn't think it would read past certain readings both high and low.

i believe you can set your limits and scaling inside romraider

commanded afr is the afr the ecu is targeting
afr is the measeured afr at front o2 sensor

maybe check maf is clean, no intake leaks check catch cans an pcv valves etc

if its a boost leak past maf, maf will meter the air then some lost so it will run rich as less air getting to engine than maf saw.

yep you can rescale front o2 to read down to about 10 afr with reasnoble accuracy, stock scaling stops at about 12 from memory

Okay sweet I am glad I was right
Is it possible that the AFR difference he is seeing is due to thr fact that the stock ecu cant read far enough in either direction to match the commanded AFR?

so your thinking the maf would cause it to throw inaccurate commands like that? 15:05 is what it wil throw on decel

afaik Commanded AFR of 15 shouldn't happen unless it's cutting fuel e.g. you're decelerating.

yes it very weird the ecu commanded afr is 15 and engine load 0.48,

i dont know whats in tune tables but it very difficult to get the ecu to target anything leaner than 14.7 under load

The open loop fuel table generally wont let you target anthing leaner than 14.7

and closed loop table is an offset from 14.7 ie values are generally negitive eg -0.3 in closed loop table ,ecu will target 14.7 - 0.3=14.4

if you put positive values or zero in the closed loop table then weird stuff happens ltft is disabled.

also i once messed up my closed loop table by highlighting entire table and applying an offset in romraider it leaned out all the cells richer than 14.7 , and the cells at 14.7 showed 14.7 , but when i drove the car it targeted rearly lean values. I had to copy in a fresh table to fix it even though it looked ok something was weird.

if you try to enter values leaner than 14.7 manually romraider wont allow it.

maybe it a rearly weird tune corruption

the stock o2 sensor scaling will read as lean as 20 on deceleration fuel cut.

ya exactly but this is a base turbo map from shiv. everyone else gets the same thing lol. it didnt use to do this. funny cause it doesnt even try to run what the command is, it just goes rich the whole time never leaner then 13.0 under throttle while it says 15.05...my values are 14.7 at the leanest, but when i start the car it will command 14.2 and get richer and richer till it locks out and just says 15.05.. im at a loss

http://datazap.me/u/grip-hooligan/ri...og=0&data=1-10

here is a log of it if you wanted to take a peak. maybe kodename has an idea (i dont know how to tag people on here:lol:)

hmm certianly weird when it gous open loop it seem to go strange and hold open loop and afr and commanded afr drift apart.

i did not study logs when i had that open loop table issue but it did similar thing,

kodename 47 is on holidays sking to tag just put @ infront of username

so i swapped maps again, at first it was kinda retarted while idling it would flicker 10.0 af then back to 14.7 then the oft shut off i adjusted the cable and the car has been perfect all day. command and all staying at 14.7 when it should, no freaking out after weeks of it doing that its just fine :iono: i guess its ok now lol

Id give it a couple of days and at least a 100 miles or more driving before you get too excited it may be related to some weird fuel trim learning or something else that only shows up after a while.

this maybe why people dont see it they only log just after a flash possibly and not after a week or so.