03-24-2019, 07:20 AM
Hi Max
The voltage meter hooked up to the O2 sensor is a great idea. There is 1 wire that you can back probe which sends the voltage signal to the ECM that you want to tap into. The wiring diagram will tell you which wire you want to back probe.
I thought the fueling on my 2014 CB was very good so never really dug into it. You sound like you are interested in this stuff. It might be worth looking at the calibration of the TPS, throttle position sensor. I am not specifically aware of it on the CB but I had a Bandit where it was possible to change the position of the TPS so the ECM thought the throttle was open more than it actually was so more fuel was added.
This stuff makes logical sense if you just understand the ECM is taking input from the various sensors, then references a vlook up table to see how long the injector needs to be on to provide the proper quantity of fuel to obtain the 14.7 to 1 ratio we have talked about. We used to put holes in the vacuum hose running to the MAP sensor, manifold absolute pressure, so the ECM thought the engine was under a greater load than it actually was and add more fuel to richen the mixture.
Where it gets tough is that some cars use a speed density system, some rely on the mass air flow sensor, and they all use different sensors. Without access to factory flowcharts or other documentation it is difficult to know where to start. I am sure it has gotten more complicated over the years but it is very logical from a cause end effect stand point. For instance at start up the ECM needs to know the temperature of the air to compute or infer the air density. Denser air needs more fuel to obtain the proper ratio we have been talking about. If the ECT, engine coolant sensor, has failed or is no longer calibrated properly than the ECM will use the wrong air mass quantity and thus add the wrong quantity of fuel.
Sorry for the long winded post I guess I am just trying to encourage anyone who is interested in this stuff not to be intimidated. Once you understand the basics it really makes a lot of sense.
The voltage meter hooked up to the O2 sensor is a great idea. There is 1 wire that you can back probe which sends the voltage signal to the ECM that you want to tap into. The wiring diagram will tell you which wire you want to back probe.
I thought the fueling on my 2014 CB was very good so never really dug into it. You sound like you are interested in this stuff. It might be worth looking at the calibration of the TPS, throttle position sensor. I am not specifically aware of it on the CB but I had a Bandit where it was possible to change the position of the TPS so the ECM thought the throttle was open more than it actually was so more fuel was added.
This stuff makes logical sense if you just understand the ECM is taking input from the various sensors, then references a vlook up table to see how long the injector needs to be on to provide the proper quantity of fuel to obtain the 14.7 to 1 ratio we have talked about. We used to put holes in the vacuum hose running to the MAP sensor, manifold absolute pressure, so the ECM thought the engine was under a greater load than it actually was and add more fuel to richen the mixture.
Where it gets tough is that some cars use a speed density system, some rely on the mass air flow sensor, and they all use different sensors. Without access to factory flowcharts or other documentation it is difficult to know where to start. I am sure it has gotten more complicated over the years but it is very logical from a cause end effect stand point. For instance at start up the ECM needs to know the temperature of the air to compute or infer the air density. Denser air needs more fuel to obtain the proper ratio we have been talking about. If the ECT, engine coolant sensor, has failed or is no longer calibrated properly than the ECM will use the wrong air mass quantity and thus add the wrong quantity of fuel.
Sorry for the long winded post I guess I am just trying to encourage anyone who is interested in this stuff not to be intimidated. Once you understand the basics it really makes a lot of sense.