how funny, it's $555.55

http://www.hondaautomotiveparts.com/auto/j...NIT+%28CABIN%29

 

Actually, this isn't the case. I put my car on the dyno about a month ago, and did some pulls with a "learned" ECU, then reset the ECU and did another pull. The RWHP and Air / Fuel Ratio plots were EXACTLY IDENTICAL before and after the ECU reset. I don't think the long and short term fuel trim has any effect on WOT.

 

that's very interesting. perhaps honda changed this, but other OBD2 honda ECUs do apply the long term trim at WOT. it stands to reason that they would, since the long term trim is meant to correct for changes in the efficiency of the fuel system and the engines breathing abilities, which are affected by things like filters that are present at WOT too.

so either honda changed it, and the trim is no longer applied at WOT, or perhaps your trim was essentially perfect and nothing was learned at all.

this is an excerpt from a pretty good series of training documents on honda pgm-fi systems :

[QUOTE]
Another concept that is related to OL/CL operation is the ability of the ECM to "learn" an engine's PW requirements. The ECM's ability to learn an individual engine's PW characteristics is called adaptive learning by Honda. The deviation of the injector PW from the factory default base PW is stored in the ECM. PW requirements are only learned while the Honda is operating in CL operation. The information is stored as the parameter long term fuel trim (LT FT).
LT FT is given as a number with 1 being no fuel trim. When the PW is wider than the factory default the number of 1 is increased by that percentage. When the PW is narrower than the factory default the number of 1 is reduced by that percentage. For example, a Honda whose PW was 10% wider than the factory default would have a LT FT of 1.1 and a Honda whose PW is 10% narrower than the factory default would be .9. Screen Capture 9-6 is showing a Honda with a LT FT of .97, which means the PW is running 3% leaner than the factory default.

 

There was a bad batch of 2000 ECUs. Mine was replace with a 2002. There was a noticable difference at idle (smoother) and right before VTEC (less notchy engagement). Two others in the Bay Area had their's changed around the same time.

 

Do you think it would be worth it to check and see if the transmission is causing the difference? My friend said if the tranny was different then it would show up during engine braking. So he suggested we get two s2000's (an '00 - '01 and an '02 - '03) and drive side by side at around 60mph in 3rd gear and both let off and see who pulls ahead. His theory is that if you're losing less in the drive train then the '02 s2000 should pull ahead of the older ones.

Anyone think it's worth a shot? If so I'll post this in the FL forum and see if anyone in my area wants to meet up.

 

[QUOTE]Originally posted by PilotChris
[B]Do you think it would be worth it to check and see if the transmission is causing the difference?

 

[QUOTE]Originally posted by gernby
[B]

There would be too many variables that could account for such a small difference.

 

Take a look at the difference in timing between a 2000 and 2002 car on the dyno:

http://www.kpj.com/S2000/DataLog.xls

The 2000 is a turbo and had an AIT of 86. My car is a 2002 with a SC and had an AIT of 118. There are of course other factors that effect timing, but the difference was huge.

-YS

 

[QUOTE]Originally posted by Yellow Streak
[B]Take a look at the difference in timing between a 2000 and 2002 car on the dyno:

http://www.kpj.com/S2000/DataLog.xls

The 2000 is a turbo and had an AIT of 86.

 

The next time Curry's has a dyno day, I will bring my notebook and collect data. They are talking about doing it some time this month.

-YS