randman2011
10+ Year Contributor
- 552
- 282
- Feb 26, 2012
-
Indianapolis,
Indiana
I am running Megasquirt MS3X but as far as I can tell, this is hardware behavior and not part of the tune. I'm losing my mind chasing this so I'm hooping that others running Speed Density might be able to help.
Tuning on 93. I used the stock spark map and all of the table axes have been adjusted to match the factory table spacing. All AFT targets in this region are 14.7:1 stoich. Here's the latest VE table:
It doesn't fully show up here because I smoothed the line out in the lower RPMs and have only tuned/logged on the highway since, but if I let the ECU autotune or enable EGO correction I always end up with a thin line of high VE from 500 RPM 80% load out to 3700 RPM 50% load. The values along that line can get as high as 109% VE even though the cells above and below are between 60% and 80%. Simply removing that line and smoothing the table always results in the exact same line reappearing, as shown by the region between 2600 and 3700 RPM above.
Here's a section of a log from that tuning session. RPM stayed between 3100 and 3300 for the duration of the log. All I did was try to get MAP to cross above and below that line a bunch of times to see what the ECU is doing.
I started out above the line at 65% load 3150 RPM and reduced throttle to cross the line down to 46% load 3100 RPM before adding throttle and crossing the line again. As MAP drops down to this high VE line, the engine leans out all the way to 17.2 AFR indicating that VE value isn't high enough, but as soon as it crosses this imaginary line it plummets to 11.3 AFR indicating that VE value is too high. So on and so forth as I cross this line across the entire VE table.
I'm logging every single parameter that MS3X has so I can display whatever might be helpful, but checking through inputs like Baro, coolant temp, MAP, manifold temp show perfectly smooth curves with the only step change input being from the wideband. CLT was a constant 175F for this entire log and MAT only varied between 57.7F and 58.5F.
Helmholtz resonances would manifest as vertical lines, not horizontal. What am I missing?
EDIT: zipped tune and log attached since they're not allowed filetypes.
Tuning on 93. I used the stock spark map and all of the table axes have been adjusted to match the factory table spacing. All AFT targets in this region are 14.7:1 stoich. Here's the latest VE table:
You must be logged in to view this image or video.
It doesn't fully show up here because I smoothed the line out in the lower RPMs and have only tuned/logged on the highway since, but if I let the ECU autotune or enable EGO correction I always end up with a thin line of high VE from 500 RPM 80% load out to 3700 RPM 50% load. The values along that line can get as high as 109% VE even though the cells above and below are between 60% and 80%. Simply removing that line and smoothing the table always results in the exact same line reappearing, as shown by the region between 2600 and 3700 RPM above.
Here's a section of a log from that tuning session. RPM stayed between 3100 and 3300 for the duration of the log. All I did was try to get MAP to cross above and below that line a bunch of times to see what the ECU is doing.
You must be logged in to view this image or video.
I started out above the line at 65% load 3150 RPM and reduced throttle to cross the line down to 46% load 3100 RPM before adding throttle and crossing the line again. As MAP drops down to this high VE line, the engine leans out all the way to 17.2 AFR indicating that VE value isn't high enough, but as soon as it crosses this imaginary line it plummets to 11.3 AFR indicating that VE value is too high. So on and so forth as I cross this line across the entire VE table.
I'm logging every single parameter that MS3X has so I can display whatever might be helpful, but checking through inputs like Baro, coolant temp, MAP, manifold temp show perfectly smooth curves with the only step change input being from the wideband. CLT was a constant 175F for this entire log and MAT only varied between 57.7F and 58.5F.
Helmholtz resonances would manifest as vertical lines, not horizontal. What am I missing?
EDIT: zipped tune and log attached since they're not allowed filetypes.
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