Discussion and questions related to the course Practical Standalone Tuning
I've looked at the webinar on this topic, but i want something clarified wrt the VE model tuning on the haltech elite platform. Andre, you touched on the fact that with a VE based fuel model, filling out the lamda target tables for base table, air compensation and coolant compensation is critical for proper operation. What I'm wanting clarified is the cold start fuel tuning process on this VE model. If the base VE table is properly tuned at normal operating temperature, can I zero out the air and coolant fuel % compensation tables and the ecu should track my corrected lamda targets on its own even without closed loop control activated? Its a bit confusing, Andre sort of hints to this being the case but then he goes on to say the approach is to fill the target tables as well as then come back and tune the compensation tables.
The ECU only corrects the VE table using the lambda targets IF you're on closed loop control. On open loop, the ECU won't compensate on its own, only by the defined compensation tables.
To answer your question: No, even if the ECU compensates by reaching the lambda target, you still need fuel compensation for cold starts. The problem is that your VE table closed loop control only focus on reaching the desired lambda target. That's OK at operating temps but things change on cold starts. Basically, you'll find that your engine runs happier with a richer AFR when cold.
The job of the closed loop is to keep the desired AFR but these compensation tables are trying to add fuel regardless of the AFR so you're always aiming to a different AFR (let's say, richer) because the situation (different coolant temp, air temp, boost, knock, etc) requires it.
I understand what you're saying fully...but I believe a VE based fuel model is supposed to be able to do what I'm asking even in open loop once the injector characterization data is accurately inputted to the ECU.
Once you tune the base VE table properly to hit your targets from the lamda target table, and your injectors are characterized properly then I believe (this is what i want clarified by the likes of Andre) if you then command a change in lamda target from the target table, being VE modelled, the ecu should be able to automatically hit the new target even if it is not running in closed loop mode.
I almost sure of the above...the purpose of this post is does it continue to work like this for the air and coolant temp lamda corrections?
It depends on the ECU. Some have multiple mixture target tables. So you can target a richer mixture when the coolant temp is colder.
For example, the MoTeC M1 ECU will uses the "richest" of the Fuel Mixture Aim tables, as the current target. There are tables for Alternate Fuel, Aux Timer, Coolant Temperature, Load Average, Exhaust Temperature, and Inlet Air Temp.
This is all independent of Closed Loop Fueling, which will just add/subtract additional trim to get you to the target.
Thanks for the respons Dave,
Yea I am aware of all of that...the question surrounds the VE modelling. A VE based fuel model is a bit different than traditional millisecond based where you would definitely need to manually tune the compensation tables to run richer for cold start and/or air temp...hoping Andre can chime in with some more insight for VE based.
The compensations might still be needed due to other issues such as poor fuel atomization at cold temperatures. They would then be needed to cause the effective fuel mass yield to match the modeled air mass in a VE based system. So the system can hit whatever target it wants without closed loop control.