deibit

I am performing some tests with my setup.. the car is a MY08 DBW F20C (European).

Mods are:

- Giles pretuned e-Manage Black (the one with the wideband feedback),
- IFR8H-11 plugs (OEM gap, 1 step colder)
- Okada Coil Pack
- ASM 07 Header
- Berk HFC
- Tanabe Concept-G exhaust

I did some tests and I logged the OBD2 sensor information.

Following Giles indications, I activated the "race pipe" setting in the e-Manage, the switch is meant to be used for people with testpipe or with HFC (for example the Berk)

I did some tests with all the ignition settings deactivated and I could read slightly consistent negative LTFT (up to -3).. meaning that the car was decreasing the time the injectors were open (correcting a "rich" mixture). those values were very similar to my car in its previous stock form.

In the last days, I have activated the mild ignition settings switch and the LTFT's turned from negative to consistently positive (up to +3)..

Is there a explanation for that change? from what I understand, the fuel trim is based on the feedback from the O2, coolant temperature, air pressure, etc etc..) but I can't see why the activation of the ignition settings caused the car to change the trim values..

Gernby

LTFT is a sort of running average of STFT (short term fuel trim), which is calculated constantly while the ECU is in closed loop. If humidity goes from 0 to 100% on a hot day, I would expect LTFT to change a few points in the positive direction, but I don't see how a small change in ignition timing would do it.

deibit

maybe the ignition settings in this pretuned emanage do not touch only ignition.. (who knows.. the maps are password protected)

I also thought that it could be a "problem" of the hot weather we are having last days..

Does anyone else has this pretuned EMU? (holyroller BADAS Black).

Today I have logged again the sensors.. in my 30minutes way to work.

Today I have seen that 90% of the time the LTFT is exactly 0, and the STFT varies between -1,5 and +3

The rpm averaged between 3.000 - 4.000 (highway cruising)

I have never experience that many 0's in the LTFT with my pretuned car (at middle load).. is that suposed to be "normal"? (seems too perfect to be normal)

spectacle

Do you have a wideband? Monitoring fuel trims is pretty useless without one

Gernby

I assumed the European DBW F20C had the same wideband O2 that the USDM DBW F22C's have. Am I wrong?

I would be really happy with a pre-tuned piggy back that resulted in LTFTs and STFTs as small as you are seeing.

deibit

I know the fuel trims are not really useful for tuning, but i would not call them useless for monitoring purposes, at least they are valid as "trend" indicators.

The BADAS has one "rudimentary" gauge implemented.. while it detects stoichiometric mix it lights one green light in the cluster.

I have a innovate wideband XD-16 serial gauge, but I did not install it yet..I only wanted to install it if it was really necessary (thats why I was monitoring the trims first..)

deibit

as far as i know the euro DBW F20C has a narrowband OEM sensor (but don't quote me on that)

I have a separate wideband sensor on the header that is the one giving feedback to the e-manage.

I am really happy with how it's working now.. but the first day of installation (and after one hour drive) I activated at the same time the "race pipe" switch and the mild settings ignition switch... directly after I got some strong hesitation at 6500rpm (uuups).

I did reset the ECU and started again from scratch.. 5 days no switch, 5 days "race pipe" switch and now 5 days "race pipe" + mild ignition settings.. now I don't get hesitation and everything works very well at any rpm range...

Gernby

I will be VERY surprised if any DBW Honda has only narrowband o2 sensors. I believe that the 05 s2000 was probably one of the last hondas to get a wideband primary o2.

deibit

could be I have looked in the European EPC and the part number of the sensor is 36531-PZX-003 (not sure if its the same as the USDM version)

urBan_dK

Fuel trims only deal with closed loop operation (e.g. cruising). However, your long term fuel trim will apply when in open loop. If you look at an OBDII logger, you will notice the STFT goes to 0 when you hit open loop while the LTFT stays active. This is why people recommend letting the car "learn" the trims for a few days after resetting the ECU before going WOT, because it's possible the LTFT isn't correct and could result in an overly lean mixture.