scareyourpassenger

It is typical for most stand alone systems but I haven't see anything about it in the flashpro. It may not exist

I didn't look into the logs with enough detail to see if that was it was doing 100% of the time.

maluch

from an engineering standpoint i would venture to say that it is very unlikely that the oem ecu does not have throttle acceleration fuel trims. The only way that these could be deemed unnecessary is if the target A/F fuel trims are very accurate and more importantly very responsive. since the stock ecu runs off the narrow band O2 sensor which has a very slow sampling rate the fuel trims are definitely not responsive.

this is not to say that i am certain that the oem ecu has throttle accel fuel trims, but it would seem really un-honda for it not to have them...maybe the flash pro just doesn't log them

Gernby

The '06+ S2000's all have wideband O2 sensors from the factory. I've been all through the FlashPro tables, settings, options, and datalogs, and have seen nothing about throttle accelleration fuel trims. However, I believe someone requested a new feature on the Hondata forum that would give fuel compensation by gear.

Gernby

Did you intend this double negative? It's not clear if you are saying it probably does have it, or probably does not have it ...

maluch

i meant that it probably does have such fuel trims...

Gernby

I think I understand what "throttle accelleration fuel trims" might be, but I believe they would probably be a separate fuel trim than STFT. It seems to me that STFT would be based solely on the input ffom the primary O2 sensor, while the "throttle accelleration fuel trim" would be a value that is solely calculated from the rate of change at the TPS. Is this correct? If so, then I believe that the limit that the FlashPro is applying to the STFT would probably (hopefully) NOT be limitting the throttle accelleration fuel trim.

maluch

throttle acceleration fuel trims are calculated solely from the TPS in AEM and DTA. This could possibly not be the case for flashpro...

i dont know too much about flashpro, how does it handle humidity change? How are these STFT different from LTFT in calculation? The only way to handle humidity apart from having a humidity sensor is by target A/F fuel trims, how does the flashpro know what component of the fuel trim is LTFT and STFT? this might be a moot point...

Gernby

That makes sense.

According to Hondata, LTFT is just a sort of rolling average of the STFT, and is stored in battery backed memory between driving cycles. Basically, if STFT is negative more than it is positive for X minutes, then the ECU decrements LTFT by 1. If it continues being negative more than positive, then it decrements LTFT by 1 again.

When in closed loop, the ECU applies LTFT and STFT to the current fuel value, but in open loop, only LTFT is applied. There is no humidity sensor, so I believe this is taken care of by STFT and LTFT via the primary O2 sensor.

maluch

Thanks for the info...

b.r.i.a.n.

i completely agree. there will always be subtle changes in afr's when running in closed loop because of many different factors that can throw off the initial fuel tables created.

as long as you fuel tables are within the right range and you don't have any major gaps between different map values you're good.