Lambda sensor reading problem

[apiazza2010]

Hello all,

I have a m400 ECU running a 07 cbr600rr.
This is the second year we run this engine.
I am having trouble with the lambda sensor. Basically it's always reading rich. No matter what I do to the tune, it's it's always fluctuating around 0.8. I can cut fuel with overall trim all the way to 50% and it still shows rich.

I thought the sensor was bad, so I bought a new one. Same LSU 4.9. I checked heater voltage and all the grounds, and it seems fine. I try air calibration again and got the same value ( around 1200).

What am I do wrong? Is this a wiring issues, or a fundamentals issue. (Timing, fuel timing).

I tried running the car and decreasing fuel pressure at the rail, to rule out stuck injector. But it kept reading around
0.8

Any help is greatly appreciated!

[apiazza2010]

Hello,

Quick update for everyone. I was still not able to find the cause of the problem. I have looked at the logged data from the test session and can see what appears to be an offset.
I need to double check if the grounding or the 5/8v sensor wire are interfering with the lambda.

Fluctuations look correct, but everything is extremely rich. Changing the Overall Trim to even -30% does not change anything in the logs. Even tho i can hear the engine rev dramatically faster making me think it is going lean.

Log_rich_lambda.PNG (17.26 KiB) Viewed 6340 times

[David Ferguson]

Have you looked at the spark plugs? Any chance you have an injector stuck open? Anything on the Diagnostics screen?

BTW - your calibration number of 1200 seems high -- we would expect closer to 1000. Perhaps you have a bad connection / corrosion on one of the Lambda Sensor connections.