Power Vision Information Thread
Intermediate
Joined: Mar 2014
Posts: 30
Likes: 0
From: WA
RD, Using autotune will calibrate your VEs. That's going to make it possible to make a pretty accurate (everything else being accurate) estimate of fuel needs for your throttle and rpm when you are in open loop (anything not stoich in your AFR map). When your AFR cell is at Stoich, the ECM will run in closed loop and tweak the fuel to give .98 lambda or 14.6 AFR as indicated by the O2 sensor. The advantage of using autotune is you can calibrate the VEs to make reasonable assurance of correct fuel settings outside of closed loop (in open loop). This doesn't necessarily need to be done if everything remains stock, but as we make changes to air cleaners and exhaust, we change how well the "air pump" (our engines) pump air. Cam, heads or head work, bigger throttle bodies, etc. make it even more important to properly calibrate the VE tables. More air means more fuel and that's where the volumetric efficiency tables come in to play. Do you really need stoich at cruise (or anywhere else for that mater)? No. But that's up to everyone's own thoughts. With a unit like the PV you can set up closed loop in any area by making the AFR 14.6 or Lambda .98, or operate outside of closed loop, but do so knowing that the PV has made the proper adjustments to your VE tables to provide assurance you're pretty close to the AFR you specified (as long as evverything is in good working order when the ATs are done). Hope this helps, and if I said something incorrectly, someone jump in and straighten me out.
Road Master
Joined: Dec 2012
Posts: 848
Likes: 30
From: CO
RD, Using autotune will calibrate your VEs. That's going to make it possible to make a pretty accurate (everything else being accurate) estimate of fuel needs for your throttle and rpm when you are in open loop (anything not stoich in your AFR map). When your AFR cell is at Stoich, the ECM will run in closed loop and tweak the fuel to give .98 lambda or 14.6 AFR as indicated by the O2 sensor. The advantage of using autotune is you can calibrate the VEs to make reasonable assurance of correct fuel settings outside of closed loop (in open loop). This doesn't necessarily need to be done if everything remains stock, but as we make changes to air cleaners and exhaust, we change how well the "air pump" (our engines) pump air. Cam, heads or head work, bigger throttle bodies, etc. make it even more important to properly calibrate the VE tables. More air means more fuel and that's where the volumetric efficiency tables come in to play. Do you really need stoich at cruise (or anywhere else for that mater)? No. But that's up to everyone's own thoughts. With a unit like the PV you can set up closed loop in any area by making the AFR 14.6 or Lambda .98, or operate outside of closed loop, but do so knowing that the PV has made the proper adjustments to your VE tables to provide assurance you're pretty close to the AFR you specified (as long as evverything is in good working order when the ATs are done). Hope this helps, and if I said something incorrectly, someone jump in and straighten me out.
Road Master
Joined: Jun 2006
Posts: 871
Likes: 7
From: Manchester, NH
So my question is, given these settings, when it's in closed loop is it actually aiming for the .977 I set, or is it aiming for stoich? Cuz if it's always aiming for stoich when in closed loop, there is no point in tweaking any of the tables that are within closed loop.
Road Master
Joined: Dec 2012
Posts: 848
Likes: 30
From: CO
Currently my PV's closed loop lambda range is .964 - 1.023. I didn't set this manually so it must be what dynojet set when they sent me the original custom tune for my setup. Does anyone know the lambda range of narrowband O2 sensors? Obviously I don't want the PV's range to be outside the sensing range of the sensors.
Road Master
Joined: Jun 2006
Posts: 871
Likes: 7
From: Manchester, NH
Currently my PV's closed loop lambda range is .964 - 1.023. I didn't set this manually so it must be what dynojet set when they sent me the original custom tune for my setup. Does anyone know the lambda range of narrowband O2 sensors? Obviously I don't want the PV's range to be outside the sensing range of the sensors.
In my particular case I can go to .976 and still be in closed loop. However when I look at the difference between .976 and .98 when converted to AFR ratio (14.33 and 14.39) I don't think that I'll notice any performance/efficiency gain on the .06 difference.
Road Captain
Joined: Nov 2012
Posts: 569
Likes: 0
From: USA
Cap and make a couple more runs.
If you still get that many maxed out then raise the CI 3% and lower the entire VE tables 3%. Then make a couple runs and see what happens. If raising the CI is the resolve only raise it enough to gain enough headroom to stay under maxing out.
Road Captain
Joined: Nov 2012
Posts: 569
Likes: 0
From: USA
Maybe you might want to contact Dynojet support and ask them. I have not reset the range that came with my setup. I would be guided by the note that is on the AFR table "Normally, using values between .98 and 1.02 allows the ECM to maintain closed loop fuel control." And from the Closed Loop Lambda Range table "A value lower than .98 will allow the ECM to operate at a ricer range for closed loop."
In my particular case I can go to .976 and still be in closed loop. However when I look at the difference between .976 and .98 when converted to AFR ratio (14.33 and 14.39) I don't think that I'll notice any performance/efficiency gain on the .06 difference.
In my particular case I can go to .976 and still be in closed loop. However when I look at the difference between .976 and .98 when converted to AFR ratio (14.33 and 14.39) I don't think that I'll notice any performance/efficiency gain on the .06 difference.
Road Captain
Joined: Nov 2012
Posts: 569
Likes: 0
From: USA
Ok good, this is what I was trying to confirm, because everyone seems to always say that closed loop is always aiming for stoich.
Currently my PV's closed loop lambda range is .964 - 1.023. I didn't set this manually so it must be what dynojet set when they sent me the original custom tune for my setup. Does anyone know the lambda range of narrowband O2 sensors? Obviously I don't want the PV's range to be outside the sensing range of the sensors.
Currently my PV's closed loop lambda range is .964 - 1.023. I didn't set this manually so it must be what dynojet set when they sent me the original custom tune for my setup. Does anyone know the lambda range of narrowband O2 sensors? Obviously I don't want the PV's range to be outside the sensing range of the sensors.
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Road Master
Joined: Dec 2012
Posts: 848
Likes: 30
From: CO
CL IS aiming for stoich. Thats where it works the best. In a cage or a water cooled bike it's fine. Not great for performance but great for mileage and emissions. Air cooled motor not so great. Thus my negativity of Closed Loop in general. If you're outside the range the Integrators will stay at 100% meaning youre not in closed loop any more.
So do you recommend just disabling CL?
Road Master
Joined: Aug 2012
Posts: 1,086
Likes: 5
From: London, UK
If you have a lambda-based tune, then closed-loop aims for your target lambda specified in the AFR table. If you have an AFR-based tune, then closed-loop aims for what it *thinks* is stoich, which you specify by voltage in the Closed-Loop-Bias table. Either way, you control where the target lambda is.