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Old 01-30-2012, 02:41 PM   #43
roger 04 rt OP
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Joined: Nov 2011
Location: Massachusetts
Oddometer: 1,940
Open Loop AFR Results

Today I got a chance to pull the fairings, lift the tank and disconnect the O2 Sensor input to the Motronic. My goal was to see what the Open Loop Air Fuel Ratios (AFR) for the Motronic 2.4 looked like.

As a reminder, I have a Wideband LC-1 installed in place of the normal Narrowband O2 sensor. Usually it is set to 14.2:1, so when the motorcycle goes closed loop, I can't tell what the Motronic would do on its own, with the O2 Sensor disconnected.

I also pulled the Pink CAT Code Plug and looked at those results as well.

Procedure:
1) Disconnect Motronic O2 Sensor
2) Disconnect BoosterPlug
3) Reset Motronic by pulling Fuse 5, etc.

Results:
From Cold Engine (40F) to Warm Engine (140F-ish): AFR Range 13:1 to 14.7:1
Warm Engine Cruise (3rd, 4th, 5th gears; 3000 to 5000 RPM): AFR Range 14.5:1 to 15.2:1

Comments: There was no sign of a rich Limp Home Mode. Without O2 Sensor connected, mixtures got leaner than 14.7:1.

Next Test:
1)Pulled Pink CAT Code Plug
2)No BoosterPlug
3)O2 Sensor Disconnected
4)Motronic Reset

Results:
Warm Engine Cruise (3rd, 4th, 5th gears; 3000 to 5000 RPM): AFR Range 14.7:1 to 15.5:1.

Comments: Pulling the Pink CAT Code plug definitely created leaner mixtures than with it in, by an amount I would guess was about 0.4 AFR leaner. I would not ride without Pink CAT Code plug installed.

Summary:
It looks to me like the stock fuel tables in the cruise range for the Motronic MA 2.4 are centered around 14.7:1 and get leaner somewhere between 2,500 and 4,000 RPM depending on TPS. I often saw AFR readings in the low 15s.

It may be that without the O2 sensor installed, and with the E10 Premium fuel I'm running, the Motronic stock fuel tables result in leaner than 14.7:1.

As you can guess, I will be reconnecting the LC-1, reprogramming my Closed Loop O2 to 14:2:1 and reconnecting the BoosterPlug for Open Loop enrichment.

PS: I broke a tab on one of the fairings in my rush to open the bike. Any suggestions for how to glue to reattach a piece to the fairing (in the cylinder head area)?
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