MoTeC Global Forum

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!

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.

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.