urBan_dK

Most certainly those are being applied. Though barometric pressure is not since we are MAP based and not MAF based.

urBan_dK

That is the number that comes up in my head. I read about it at some point. Hence the IIRC. I do know for certain that the CEL comes on at some LTFT value >10%.

Gernby

The MAP goes up and down with barometric pressure. IIRC, there is also a pressure sensor inside the ECU.

s2konroids

Interesting thread, IIRC just because the ECU throws a CEL for 'system too rich' it doesn't mean it goes into limp mode - I'm pretty sure about this.

I dont think anyone also mentioned in a simple way the STFT is gradually applied to the LTFT.

Also, i pretty sure our European F20c's dont have primary widebands o2 sensors

Gernby

I made a post in the Asian / European FlashPro thread asking if anyone can confirm whether their primary O2 sensors are wide or narrow band. I can't imagine why Honda would build 2 totally different ECU's for the DBW S2000's, and I really doubt Hondata would have supported both versions if they were that different too.

spectacle

Sigh. I've explained this concept almost a dozen times it seems like on this forum. Here's one more shot.

If you unplugged your o2, the car will throw a code and still run 90% fine. The o2 sensor and closed loop operation is not designed to make up any variances in wear and tear over time at all. Its singular purpose is to let the motor burn fuel at stoich under light loads for the best fuel economy+throttle response. That's it. Now let me clear a few things up.

1. Piggybacks like VAFC's do not function correctly in closed loop because that is the way the system is designed. If you make your corrections through the unit in open loop only, they will not be erased or tuned out.

Ok now I'm having deja vu. I just typed this all out like a month ago. Goes to search...

Man I just saved myself a whole 10 mins of typing


[QUOTE=spectacle,Jun 28 2010, 01:58 PM]Challenge taken.

Your ECU is either in one of two modes in operation: open or closed loop. 95% of the time in normal everyday driving, you're in closed loop. Closed loop is also a way of stating the ECU is taking feedback from the primary o2 sensor in order to keep the a/f mixture at stoich (~14.7 on gas). Stoich is air fuel mixture where gas burns the most efficiently and also where most motors are happy when crusing or under light load. There are two trims under closed loop feedback, short term and long term. As you drive over time, the ECU automatically adds or subtracts fuel (in closed loop) to keep the air fuel at ~14.7. How much it + or - is called the short fuel trim and it is expressed as a percentage. The closer the car is in health and the environment in which Honda programmed the stock ECU, the smaller this value will be. It is CONSTANTLY changing (every couple of secs) based on ambient temp, air filter restrictions, elevation, etc etc. Over time, the ECU is smart enough to know that within the last X amount of time (I don't remember the interval) that the average correction it had to make at certain load breakpoints was 'X'% and it applies that percentage across the board (again still in closed loop). This is called the long term trim. This doesn't change as often.

deibit

yes this I got it before.. I just don't find a logical explanation on *why* LTFTs would not be useful as corrective parameters in Open Loop.. but well if it's this way, then it's this way.

What I don't buy is the statment that in Open Loop "the fuel values are derived from the table in the ECU with no changes" theose values might be derived from the internal tables from the ECU but *must* be corrected with the information coming from some other sensors (like MAP, IAT, ECT, TPS. etc etc..). It can't be all static (for obvious reasons)

Gernby

The MAP, IAT, and ECT sensors are all definitely used to determine fuel at WOT.

spectacle

For clarification - IAT, ECT are static correction values that will affect the fueling regardless of closed or open loop. So for example in open loop the fuel value in the tables are what they are and do not change, but the amount of fuel delivered can be added or subtracted depending on where the parameter reference is in that respective table.