Someone please explain how the ECM sets up the AFR as it is input in the AFR tables if the AFR is out of the closed loop range. To rephrase my question, if I populate the cells in the AFR table with 13.8 how does the ECM know what to do to achieve this since there is no Closed Loop Feed Back? Am I correct in assuming that this requires a correct VE calibration as a point of reference?

Is there a Formula to derive efective AFR from CLB voltage?

 

Yes, the ve tables is what is used to calibrate the ecm so that the delivered afr matchs the requested afr. It uses the ideal gas law, more or less, to estimate the mass of air into the cylinder based upon conditions in the intake, i.e. map pressure and intake air temp. The ve table is basically a multiplier on that value saying what's likely to have actually made it into the cylinder.

I've not seen a formula for converting CLB voltage to an afr. Your best bet would be to find a chart. It is not linear. You can adjust to about +/- 0.5 afr, i.e. 14.1 to 15.1 afr. 15.1 afr is about 0.4V, 14.1 is about 0.8v nd 14.6 is 0.48v. It's a zirconia narrow band o2 sensor. Beyond the 0.4v to 0.8v range the sensor is very sensitive to variations in heat within the normal operating range of the engine and small changes in voltage represent large changes in AFR. Generally the CLB table is used to transition into open loop.

 

Narrow-band 02 sensors suck. Like LilBusyWizer says, the ECM is ESTIMATING, what the MAP pressure is. This translates to a guess as to what the what the correct timing should be given what the load/AFR is. Potentially not good. Sounds like you have a pretty good understanding of what going on, have you looked at a wide-band 02 and ECM capable setup?

 

Ok, I have done a data run with my SEST and tweaked the VE table in accordance w/the VE real data. Probably need to do a couple more runs to dial it in. Now what about VE values outside of the closed loop range? How do we get these?

I have considered a system such as ThunderMax Autotune. Don't really want to throw $900 at fuel management, but maybe in the long run it's the best option. I don't really have access to a tuner I trust.

 

I'm not sure VE New is quite what you think it is. I think you really need to use the O2 and O2 integrator values with the afr set in range of the O2 sensors. Regretably the SEST is bugged so that it doesn't show those values.

 

Would you please elaborate on this?

 

The easiest way to understand this is that the ECM uses math to calculate values. We can argue all day as to how good the ECM is but the truth is, that it runs the engines just fine. VE is the error correction in the math so that it calculates things properly, so once you have the VE set properly the rest of it works just fine from a fuel standpoint. So now you need to get the VE values setup correctly and how do you do it? With a dyno and test equipment you can adjust things until you get what your looking for as an average. Without a dyno you have to set things up to gather the necessary information and filter out all the unwanted/bad data. Make corrections then test again.

This is just what we designed Mastertune and V-tune to do for you. We correct the VE values using the range that the switching sensors can measure properly. Then, when completed set the AFR table back to what you want/need and allow the ECM to do it's job. Trying to do it without the knowledge of what the ECM is doing and what to filter out is a good guess at best.

 

Hum, well, looking at the manual it says the VE New is what should be in the VE Table based upon feed back from the O2 sensors. So I guess it is valid to use that way.

I don't believe you need to be in closed loop for the ve new, but, rather, just in range of the o2 sensor for it to be meaningful. I think it would be best if you weren't in closed loop while trying to calibrate the ve tables. So set it to like 14.3 afr across the board while doing calibrations. Really, until you have a map you are confident of you should only run the map for testing and return to the starting map when done testing. Once you feel confident of the map go buy a dyno run for like $50 to see how well you actually did.

Hopefully this is a hobby for you because it's likely going to be a long slow process. It takes a skilled technician several hours on a dyno. The dyno makes it easy to create controlled test conditions, like holding a cell to collect data. It's going to be a time consuming process on the road. No biggie if it's mainly entertainment.

 

Recorded a rather long run yesterday, varying conditions, some slow, some fast cruising, some spanking it kinda hard from a stop. Looks like this would be easier if the SEST software would put the VE new values into a matrix w/the appropriate TPS and RPM values. I looked at the structure of the run file, seems like it would be easy enough to parse out the appropriate data into something that could be put into a spreadsheet and then pasted into the VE cells. I take it Mastertune can produce something along these lines?

Interesting that I had put regular gas in the bike and didn't see a trace of knock.

 

boy do i feel like a moron...