Tuning for gas mileage
Tuning for gas mileage
I have been trying to figure out how to tune closed loop AFR from 14.7:1 whene cruising to 15.5:1. I have read that an AFR in the area of 15.5:1 is where the best for gas mileage.
I believe that to tune in closed loop you will have to trick the stock O2 sensor into thinking it is in open loop. So today I disconnected my stock O2 sensor to see what will happen. The AFR went rich to around 12-11.8:1 when cruising and when at idle. Now, I want to use the Xede to change the AFR to 15.5:1. When I cruise I am usually in the 1500-3000 rpm area and the 15-30 load point. That is the area that I will tune to 15.5:1 inorder to improve gas mileage.
My question is this: Are there any ill effects, besides a CEL, to running with the O2 sensor disconnected?
I believe that to tune in closed loop you will have to trick the stock O2 sensor into thinking it is in open loop. So today I disconnected my stock O2 sensor to see what will happen. The AFR went rich to around 12-11.8:1 when cruising and when at idle. Now, I want to use the Xede to change the AFR to 15.5:1. When I cruise I am usually in the 1500-3000 rpm area and the 15-30 load point. That is the area that I will tune to 15.5:1 inorder to improve gas mileage.
My question is this: Are there any ill effects, besides a CEL, to running with the O2 sensor disconnected?
WOW, I have been thinking about updating this post. Well, I tried disconnecting the O2 sensor and using the Xede to tune closed loop. The results were very inconsistent. soemtimes the AFR during cruising would hit the desired target of around 15.5:1 and sometimes it does not. The AFR was all over the place.
Not being someone who would give up, I did some more research and I found out that the Innovate LM-1 unit that I have can simulate a NBO2 sensor and send that signal to the ECU and make the ECU believe that it should run at 15.5:1 AFR. If you have an LM-1 use the Analog Out 1 and connect from the LM-1 to the ECU pin 76. Next, disconnect the O2 sensor signal from the engine bay. You must keep the O2 sensor heater connected. Then use the LM programmer software and program your Analog Out 1 to run at 15.5:1 in closed loop.
It WORKED. Now my car runs at the AFR of my choosing in closed loop. And get this, I did NOT get a CEL. The ECU thinks that it is still getting a signal from the NBO2, but in reality I am sending the ECU the signal that I want to control closed loop operation.
I have not done enough testing to see if I will get better gas mileage yet. I will run through a couple of tanks of gas in the next few weeks and then I could tell.
This is the AFR while cruising on the FWY @ 65 mph before I changed closed loop
And this is the AFR after I changed it
Not being someone who would give up, I did some more research and I found out that the Innovate LM-1 unit that I have can simulate a NBO2 sensor and send that signal to the ECU and make the ECU believe that it should run at 15.5:1 AFR. If you have an LM-1 use the Analog Out 1 and connect from the LM-1 to the ECU pin 76. Next, disconnect the O2 sensor signal from the engine bay. You must keep the O2 sensor heater connected. Then use the LM programmer software and program your Analog Out 1 to run at 15.5:1 in closed loop.
It WORKED. Now my car runs at the AFR of my choosing in closed loop. And get this, I did NOT get a CEL. The ECU thinks that it is still getting a signal from the NBO2, but in reality I am sending the ECU the signal that I want to control closed loop operation.
I have not done enough testing to see if I will get better gas mileage yet. I will run through a couple of tanks of gas in the next few weeks and then I could tell.
This is the AFR while cruising on the FWY @ 65 mph before I changed closed loop
And this is the AFR after I changed it
