Blip Response Time

[VtrSp1]

@Adamw i try to learn how the Blip end mode set to predictive - blip response time change versus the Blip End mode set to Shift end in a sequential gearbox with lever closed loop shifting..

I search on the help manual but it's not explained very well.

On a Sequential Gearbox with closed loop shifting gear position sensor and loadcell knob

- Blip End mode set to Shift End mean that blip is removed when the next gear is engaged

- Blip End mode set to Predictive what mean? The ecu can't monitor the Rpm change vs a target Rpm because there isn't a Gear ratio table filled with the ratio but there is a voltage table

[Adamw]

It does still use the gear ratio table but there is a bit of a trick to set it up:  

With gear detection mode set to analog position, drive the car through all gears while logging (can be on dyno or just jacked up in air).  

After the run, look at the parameter "Gear Ratio Calc" in the log and note down the ratio for each gear.  Then go to gear detection settings, temporarily set gear detection mode to "RPM/Speed" and gear detection type to "user defined".  Enter the ratio numbers that you just noted down from your log.  Do a store, then change gear detection mode back to analog.  The gear ratio table is still stored and used in the back ground, just it is no longer visable.  

[VtrSp1]

@Adamw this is very helpfull information!

So after this setup and Blip End set to Predictive :

- the ecu when i do the downshift  open the throttle as the value in the Gear Throttle trim

- the ecu monitor the Rpm change and do a background calculation for the Rpm target in the next gear

- the ecu work to remove the Blip when the RPM in the next gear is at target

It's the ecu logic for the Blip set to Predictive?

and.. the Blip Response table , what change?

 

[Adamw]

24 minutes ago, VtrSp1 said:

So after this setup and Blip End set to Predictive :

- the ecu when i do the downshift  open the throttle as the value in the Gear Throttle trim

- the ecu monitor the Rpm change and do a background calculation for the Rpm target in the next gear

- the ecu work to remove the Blip when the RPM in the next gear is at target

It's the ecu logic for the Blip set to Predictive?

Yes that is correct. 

 

25 minutes ago, VtrSp1 said:

the Blip Response table , what change?

The blip respoonse time is the time it takes for the engine RPM to respond to the removal of the blip (The manifold is already full of air and the throttle takes time to move, so the RPM keeps going up for a little while after you turn off the blip).  

So lets say the ECU has calculated based on the current RPM rate that the engine will reach the target RPM for the next gear in 100ms.  If your blip response time is set to 40ms, it will turn off the blip after 60ms. 

[VtrSp1]

@Adamw this sound good..

In a typical downshift from 4th to 3rd under hard braking condition with Blip set to end mode as Shift end the e-throttle take about 100 ms for reach the target and  80 mS for close when the Gear Throttle trim is removed from my log.

This cause me a engine push forward after the downshift when i re-engage the clutch

This is a PID setting wrong for e-throttle or change the setting to blip set as predictive can solve me the issue?

[Adamw]

Predictive end will probably help the pushing effect, it doesnt always solve the problem with some engines.  The more modern strategy is to apply a cut right after the blip but you dont have that option in G4+.

[tbase]

On 8/4/2021 at 4:12 AM, Adamw said:

Predictive end will probably help the pushing effect, it doesnt always solve the problem with some engines.  The more modern strategy is to apply a cut right after the blip but you dont have that option in G4+.

@Adamw Does it has in G4X?

[Adamw]

It will soon, there is a much more complete gear shift control function coming for G4X, I was in the middle of testing it before NZ went into lockdown so it has been delayed a bit.  Maybe a couple of months away. 

[VtrSp1]

@Adamw,I recently had the opportunity to do some circuit tests and tried different Blip response time settings for the Blip Predictive. But I can't see big differences going from 60-80-100 mS as if nothing really changed. The downshift is now smooth and doesn't push the car forward as much as it did when I used Blip end mode to shift end. I had also tried to use a second e-throttle table controlled by a Virtual aux and the car was pushed forward as with the blip end to shift end. The predictive Blip after having calibrated the gears with the gear ratio table as you suggested now works well. The only doubt is that I don't see anything change as the predictive time changes.

I upload three screenshot, 60 , 80 and 100 mS in sequence...

 

 

[Adamw]

In all of those screenshots above the shift has ended before the RPM has even increased, so blip has been terminated at the same time.   

[tbase]

On 11/10/2021 at 5:12 AM, VtrSp1 said:

@Adamw,I recently had the opportunity to do some circuit tests and tried different Blip response time settings for the Blip Predictive. But I can't see big differences going from 60-80-100 mS as if nothing really changed. The downshift is now smooth and doesn't push the car forward as much as it did when I used Blip end mode to shift end. I had also tried to use a second e-throttle table controlled by a Virtual aux and the car was pushed forward as with the blip end to shift end. The predictive Blip after having calibrated the gears with the gear ratio table as you suggested now works well. The only doubt is that I don't see anything change as the predictive time changes.

I upload three screenshot, 60 , 80 and 100 mS in sequence...

 

 

@VtrSp1 I guess this is downshift without using clutch right?

@Adamw So means the blip on predictive mode will works smoother with using clutch so shift end will take longer. Am I correct?

[Adamw]

18 hours ago, tbase said:

So means the blip on predictive mode will works smoother with using clutch so shift end will take longer. Am I correct?

Clutch shouldnt make any difference, the shift will end whenever your end conditions are met, this could be gear barrel position, a timer based shift or a DI.