Hey guys, I'm trying to figure out an issue with seeing throttle angle error at idle. The throttle angle will fluctuate between ~3.5* and ~4* while idling. I would like it to be steady and have as close to zero error as possible.
So far, the only solution I have found is to adjust the throttle body data. Using that approach I was able to achieve results that I was satisfied with. However, knowing that I have a stock throttle body, I question if this is the proper solution. I have attempted to adjust DD up and down in the idle area with no positive results. I have also attempted to adjust the torque/inverse tables in the idle area, which only led to IPC Errors and a worse idle, whether I adjusted up or down.
Seeking some guidance on this, I'm still learning so I'm scratching my head at this point. If adjusting the throttle body data is the correct solution I'm cool with that, I just don't want to be doing this the wrong way.
Attached is a log showing the idle issue, and its corresponding tune.
No ideas? I want to believe my error lies in the torque/inverse tables, and perhaps I am just adjusting them improperly. Upon further logging there is ETC Error riddled throughout the entire RPM/Load Range, but little to no IPC Error.
Throttle angle errors are unavoidable. These angle errors go unnoticed unless you have IPC Wheel Torque Error fluctuating as well. All of your tables interpolate. As you accelerate, your load increases, your mapped point weights will flow, your torque/inverse tables interpolate with in calculating many formulas. Engine Brake Torque is one. This checks your throttle body angle, how much air mass is flowing. Essentially, driver demand or driver request through ETC. This is where you get the values for throttle angle error PID. It's the difference between driver request and actual calculated torque but converted into different units. Both ETC Area and Predicted Throttle Angle can be adjusted. Changing your Torque/inverse tables can keep you angle error closer to 0 too. I recommend sticking to one. ETC is less difficult.
Well something I am noticing is that when idling and returning to idle , the greater my throttle angle errors are , the more of that ‘oscillation’ I see. Going down the ETC route I’ve got my errors to less than .1* and it helped the car not overshoot target idle as much when clutching in and returning to idle, particularly with AC turned on.
I guess the only question I’m left with is , how to I properly adjust torque tables using data I gather from logging ?
I have attempted to try two methods as seen in another thread.
1. Logging ETC Error against rpm and air load , and using that data to apply changes to the torque table, then calculating inverse.
2. Logging Air load against rpm and etc torque request, putting these load values in the inverse table, smoothing and then calculating the inverse for the torque table.
Both methods I filtered by mapped point. After not getting anywhere with either of those methods , and perhaps that is of my own error in some way. I simply attempted to make slight changes to the idle area to see if I could achieves any results at all, changing numbers by maybe 10-25% through the several files I tried. All achieved nothing but more errors.
This is why things aren't adding up for you. You created your own angles in your mapped points and assigned those angles to optimal stability and emissions reduction and also included them in your fuel economy table. You have a repetive cycle.. Attempting optimal stability, and you're not logging throttle angle source but I'm sure it's in torque control since your spark source in idle feedback. To reach Optimal Stability, your mapped point weights would have to flow 0 through 6. it's only getting .2% of Mapped Point 1, but that's enough to rise your air load from mapped point 1. The torque tables are set up for a different set of angles rated at different torque. I'll just leave a screen shot. angleerror.JPG
Disable the oscillation switch in the Torque Management. Change your distance tables back to stock and if it changes your results any. Emission reduction normally uses mapped point 10 which has IVO -30, EVC 0 which is a type of EGR, Advancing the intake at low RPM also help get rid of blow back which increases fuel economy and stabializes your idle.
If you don't want to use 10, then use 0 VCT, timing, torque, everything will desire 0 instead of 7.
Thanks for pointing that out. I went ahead and made the changes, put VCT distance tables and MPs back to stock , also disabled the Oscillation Switch as you recommended. Did a quick drive to test it out, I will say that I think there is slightly less ETC Angle Error but it is still there. Attached is the log with its corresponding calibration. Perhaps next I should try to adjust torque tables and see if I can net any positive results?
As well there is still a strange oscillation that you can see when I am parked and idling, where Throttle Angle is flat and spark is relatively flat AC is off, and then where it begins fluctuating is AC on.
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