HE351ve install / retrofit 2nd Gen Cummins

[Vais01]

It "hiccups" rather than barks now. I still need to work out a way to delay the turbo from closing fast on let off. Shouldn't be hard once I look into since I know what my throttle position is. I might just raise my walkdown rpm or the rpm that the turbo tried to walk the vane position down so idle rpm is around 12k

I'll try to get a video soon here.

The trick is to allow the vanes to suddenly open up upon throttle lift this prevents the so called bark. It kind of makes a pulsating whooshing noise when the drive pressure is still high. This is another reason I finally got away from this VGT because the inputs to correctly operate the vane controller are immense. Try limiting boost levels to 32 PSI max and see if that helps. That's what I did with mine and it prevented the turbo from barking.

[Me78569]

        if (ThrottlePosition < 2) {  // Idle Section
            if(turbo_rpm <= idle_rpm) { //idle rpm is 12000
             vane_position = idle_position;
             idle_walkdown_mode = false;
          } else {
            if (turbo_rpm <= idle_walkdown_rpm) { idle_walkdown_mode = true; } else { idle_walkdown_mode = false; } //walk down rpm is 20000
            if (idle_walkdown_mode) { vane_position = constrain((final_vane_position - 10),idle_position-two_cm, 800); }
            else {vane_position = min_position;} // if turbo rpm is above 20000 then it will set vanes to full open  ( min_position is full open for some reason haha)          
          }

Here you can see what I am doing when there is no throttle input.

 

In short.

 

-no throttle and turbo is below 12000 rpm it will go to about 12cm

-no throttle and turbo is above 12000 but below 20000 then it will walk from whatever the last position was to 12cm slowly to bring turbo speed down slowly

-no throttle and above 20000 rpm it will walk the turbo position towards full open.

 

The vane positions will move no faster than 1/4 cm per movement so it will "walk" to the commanded position unless turbo rpm is above 100000 in which case it will jump.   

 

That is how I am handling the full throttle to off throttle.  If turbo RPMS are high enough to not be considered idle/walkdown idle (20000) it will always increase turbo size until turbo speed drops below 20000, then it will start to walk down to 12cm

 

I wouldn't call what the turbo does a "bark"  more of a whoosh or huff.  

[Vais01]

        if (ThrottlePosition < 2) {  // Idle Section
            if(turbo_rpm <= idle_rpm) { //idle rpm is 12000
             vane_position = idle_position;
             idle_walkdown_mode = false;
          } else {
            if (turbo_rpm <= idle_walkdown_rpm) { idle_walkdown_mode = true; } else { idle_walkdown_mode = false; } //walk down rpm is 20000
            if (idle_walkdown_mode) { vane_position = constrain((final_vane_position - 10),idle_position-two_cm, 800); }
            else {vane_position = min_position;} // if turbo rpm is above 20000 then it will set vanes to full open  ( min_position is full open for some reason haha)          
          }

Here you can see what I am doing when there is no throttle input.

In short.

-no throttle and turbo is below 12000 rpm it will go to about 12cm

-no throttle and turbo is above 12000 but below 20000 then it will walk from whatever the last position was to 12cm slowly to bring turbo speed down slowly

-no throttle and above 20000 rpm it will walk the turbo position towards full open.

The vane positions will move no faster than 1/4 cm per movement so it will "walk" to the commanded position unless turbo rpm is above 100000 in which case it will jump.

That is how I am handling the full throttle to off throttle. If turbo RPMS are high enough to not be considered idle/walkdown idle (20000) it will always increase turbo size until turbo speed drops below 20000, then it will start to walk down to 12cm

I wouldn't call what the turbo does a "bark" more of a whoosh or huff.

On my old configuration I had wrote one map that never made any noise when rapidly releasing the throttle even at max boost. The truck ran strong but the top end was lacking until I added some additional boost (32 then up to 35). For some reason with the additional boost the turbo would create a rapid chirping/whooshing noise with 3 additional PSI of boost. My current turbo and truck configuration has no chirping/whooshing or barking. Then again I do believe there are too many necessary parameters to monitor to correctly operate one of these VGT turbos.

[Me78569]

The code is starting to get really good.  I am now seeing 35psi on a hard run without any barking. 

 

I have also cleaned up most of the off idle smoke, and cruising to wot smoke.

 

you need to know shaft speed, TPS, boost and drive to tune this turbo.

[Vais01]

The code is starting to get really good. I am now seeing 35psi on a hard run without any barking.

I have also cleaned up most of the off idle smoke, and cruising to wot smoke.

you need to know shaft speed, TPS, boost and drive to tune this turbo.

I agree. The trick also is air density from altitude or temperature.

[Me78569]

Thankfully I can tune the curve to the "normal" altitude and temp.  

 

 

I would love to talk with a Cummins/Holset tech about how they tune the turbo.  

[bjytech]

On the Cummins ISX's that have the VGT turbos, I know it uses the following for controlling the turbo. 

• Intake manifold pressure 
• Intake manifold temp
• Engine load
• Exhaust back pressure (in the manifold)
• Turbo shaft speed
• Turbo compressor intake temp

 

There could be a couple others such as the TPS and fueling rate that play in as well but I'm not sure about those, and of course there are times the ECM will control the turbo/whole engine very differently than normal like when it runs a re-gen or is in engine warm-up operating mode on a cold day.

[Me78569]

Yea I would assume they have a pretty in depth map for it.  

 

I wonder how far off base I am haha,