Discussion and questions related to the course Practical Diesel Tuning
I'm wondering what these tables do specifically and when making changes to them what effects does it have on the engines operation. I learned the transmission uses these tables in some capacity by trail and error making changes to them and data logging. I then re-scaled and increased them by the same percent i increased my torque to fuel amount. This really seemed to smooth out the pedal to power delivery making the truck feel more like stock. I had made many changes to the pedal map and other tables trying to achieve this feel but it wasn't previously possible until adjusting these tables. I recently purchased the newly released diesel course and didn't see any mention of them. Granted it is a new course i just thought there would be some mention that'd point me in the right direction. These pics are from a 2018 F250 6.7L diesel using HPTuners.
I'll be as transparent as I can be on this topic. I've not played with these tables before on the Powerstroke. I can only think of 3 reasons why the ECM would want to convert fuel rate in a percentage of load.
1. When controlling or making small adjustments to the fuel rate for shift de-fuel or throttle smoothing it may be helpful to the ECM to work in load percentages.
Example a : Load percentage change rate cannot exceed x% per second during throttle transitions.
Example b : If the shift duration is not meeting the target time, the ECM may find it useful to adjust the load % on the entrance or exit of the shift
2. The Toyota Camry case. The ECM is monitoring desired load vs. actual and making the sure it stays within it's allowance. I think this case is less likely to be the culprit here as the ECM already knows desired torque and actual.
3. Load percentage is an SAE PID if memory serves. It may be as simple as satisfying that calc.
I have some docs that might be more helpful on the topic. I'll take a look through them next week and see if I can line the HPT name of this table up to the factory definition.
Hope this get helps a bit, maybe get your wheels turning. Wish I could offer more off the top of my head.
Yeah i don't know how to explain what the changes do, i can't find any definitive data on the engine side of what it's doing. I can say this, if you look at ford's mustang ECU's they do look for actual load to match desired based on these tables, but instead of being a percentage like the diesel tables it's a actual torque number. I had issues with the ECU throwing a reduced engine power because of a torque related issue, this would only occur when i increased fuel and started making more power. So to solve it i set "allowed difference" from 50% to 100% and Level two offset from 12% to 100%. I haven't had an issue thus far, but I don't think it's the proper way to do it though, more of a band-aid IMO. I'm leaning towards these tables having something to do with because where else would i alter the engines theoretical torque output? I don't feel as though the torque to fuel is the only thing the ECU uses for calculating torque, But i could be wrong. I'd love to see anything on this topic from the OE's.