Live data parameters for stock engine?
 

Hi everyone, I recently ran my car on a hub dyno against a fellow competitor/friend's autocross car. The cars' modifications that might impact engine performance are minimal (air filter and cat back exhaust).

My car was running about 2.5% weaker than my buddy's car across the powerband, and I am hunting for causes. We have considered things like oil viscosity, gas, condition of driveshafts, air filters.

I am about to replace the MAF and plugs, but I pulled some live data to have a benchmark for the effects of changes I make.

2013 FR-S, 90,000 miles. New direct injectors, cleaned port injectors, new O2 sensor within the last year. Plugs have less than 30k on them. Updated 2015 coils and wiring harness last year.

Here are some of the readings, after running for 12 minutes, at idle:

LOAD-PCT 22.7-25.5
STFT 0.8
LTFT 7.0
MAP (inHg) 8.56 - 8.86
SPARKADV 12.5
MAF(g/s) 2.02 - 2.22
TP(%) 13.7
O2S12(V) 0.715 - 0.730
FRP(psi) 565.00 - 575.80
LAMBDA11 0.994-1.004
O2S11(v) 2.184-2.220
FLI(%) 74.1
CATEMP(F) 544.10
LOAD-ABS(%) 15.3 - 16.1
TP_R(%) 2.0
TP_B(%) 30.6
APP_D(%) 13.3
APP_E(%) 12.9
TAC_PCT(%) 0.0
EVAP_VPA(inH2o) 392.77
APP_R(%) 0.0

I've read that a LTFT percentage within 10% is acceptable, but I am interested in whether that is the case for the 2013 FR-S.

Does anyone see anything here that is suspicious?

Is fuel rail pressure really that high?

Is there a source for the expected "live data" parameters for this engine somewhere?

Thanks in advance.

Those instant data at idle are useless
You need to post a full log with you pulling the 3rd gear full throttle till redline

Both same year the cars?
Stock tune?
Pre restyling stock tune are garbage, they apply a different LTFT into open loop every time so you can end up richer or leaner than your average just depending on some stupid learning that the ecu does even before going into open loop
Restyling stock tunes are better at this

Do you mean pre-facelift? Yes, all cars in the class are 2013-16 BRZ or FR-S. The cars are not permitted to have a tune. Both cars are 2013s.

This is interesting about applying different LTFT at different times in open loop.

Are you saying that depending on what the car has learned during closed loop, the fuel is adjusted during full throttle/open loop?

That does not sound like a bad idea theoretically, but I suppose the mapping adjustments could be poorly done.

Thank you for this information.

Every engine is different. A different day yours may make more power.

yes, that 's how LTFT applied in open loop works
it should learn the correction around 2.8-3v of maf voltage which is more or less the threshold between closed and open loop and then the ecu applies it into the open loop section
I dont know exactly how this work and actually not really interested anyway as i disable LTFT in open loop anyway in all the tunes I do

in stock tune there is a +-40% margin of LTFT that can be applied
In openflash tunes is tamed to 2%
in custom tunes is basically turned off by every tuner

an aftermarket filter panel like k&n for example usually already leans things out , but how LTFT reacts to that can be at times really random, that's why stock tune is garbage for this

It is interesting that you mention the K&N filter, as the other car was running one, and for fun we threw it in my car (which had a stock filter) and did another pull or two. My car gained 2 hp generally over the powerband. It sounds like it might not have been the filter, but rather whatever the fuel amount was being put out at that time was "happier" with more air, and thus the 2 hp increase.

@tomm.brz, how do you disable LTFT in OL? Also, wanted to pick your thoughts on why you do so?

because it has sense

and also ecutek suggests to zero it
and every other tuner does so

it is done because you don t need it and it s just annoying, yyou get to scale the maf/speed density anyway to have it perfect
why have it modified if you already have it on spot?

in ecutek they are called
Fuel trim long term maximum
Fuel trim long term minimum

put them to zero

yes kind of
a better panel like k&n lets more air and they also mess with the sampled part that flows through the maf
Ideally a flow inside the intake tube where the maf is is a laminar flow with no turbulebce but in reality it is not but stock airbox is very good at keeping turbulence at minimum

they mess with the scaling usually making everywhere leaner, so the leaner it gets the more power it gives because stock tune is too rich

this is quite different with restyling cars as the tune most of the time is in closed loop and a lot leaner .. but after 6400 rpm and also when exhaust temp gets very hot it turns back to "old" settings like pre restyling cars' tunes

if you can t tune it ur best bet is just a filter panel like your friend

Thanks. Am just trying to understand it from an OEM's perspective - what I can think of is that it is done to have the AFR generally 'pushed' in the right direction of the trims so the AFR would get closer to the OL values in the table, as they would assume with different variations coming from each car.

But turning off LTFT would possibly not work well for a set-and-forget setup, ie. I would think that if the MAF sensor gets dirtier over time it would start to deviate from that perfect alignment, and LTFT will not be there to alleviate/reduce its impact of the MAF voltage drift.

Didn't see any other explanation elsewhere, so this is purely my guess.

of course ltft in open loop is thought as a band aid for a tune that is identical for every car out there in the world
Tuners don't think like OEM in some things, quite the opposite because oem need to respect emissions somehow and accept a lot of compromise
Tuners go for precision and each car needs different settings, while 1 single tune of OEM must work in millions of cars potentially

LTFT is anyway kept enabled in closed loop (low mid loads ) all the time as it is helpfull and can help diagnosis in case of problems ( that s the value that triggers the CELs for too lean or too rich)
and in open loop it just tries to compensate whatever condition is affecting the AFR
If it calculates that the fuel trims in closed loop are now averaging in whatever direction, it applies an LTFT in open loop too
but it just hopes to have done a positive thing, it doesn t know the result because it doesn't check, it is in fact an open loop

>2017 cars have closed loop also at WOT untill 6400rpm so they are leaner and less erratic

having closed loop at WOT can be dangerous as if the sensor gets fucked up and start to command lean afr at WOT at high rpm, engine can explode, if no failsafe is taken in account against this
but usually if afr gets so lean , exhaust temperature will raise and the ecu then triggers the closed-looping off and put a rich commanded afr in open loop

Sorry for this novice question, but where is the car measuring exhaust gas temp, and is that the CATEMP(F) 544.10 reading I see in my live data? Thanks in advance.

It's an estimation - based off the O2 sensors I believe.

yes it s extracted from lambda current
btw is surprisingly quite accurate