Ranger 3.2 VNT control

[Huskydog78]

Hi all.
PX2 2016 (DPF model)
Cars in the workshop again with another dead turbo. Exhaust turbine has lost fins. VNT components are intact but jammed up with wheel schrapnel.
Have a local turbo workshop inspecting it this time to hopefully identify the root cause.
Mods: DPF delete. Cat delete. Open 3" exhaust with glass pack muffler. EGR off in software. Intercooler. High flow turbo (PX1 with GTX 44mm wheel). Custom tune.
From day 1 I've had issues with low load bucking/shudder. Not obvious in manifold pressure logs but under light accel or decel it will buck as if I'm in too high a gear for the rpm. Tuner is at a loss to identify the issue and control it.
Turbo guy has backed my suspicions that it could be due to the VNT closing down too much, effectively exhaust braking the engine.
So questions: Do my thoughts seem plausible? Could the EGR disable have upset the minimum exhaust turbine flow? Is the VNT 0% - 100% control range adjustable from the ECU, or is it flashed into the actuator? Is there a difference in the internal calibration of the PX1 and PX2 actuators?
Many thanks
Peter

[Aus_spec_ranger]

Send me your tune I would love to compere it to mine....I think your correct with the turbo vane closing too much causing bucking and this might of killed your turbo....I never had this issue at all....tuned my car at 17,000km.....now I have 124,000km....turbo sounds in very good condition by hearing it spin a long time when I shut it off. I also have E gR and dpf off.....egr off will never cause this....unless it was never turned off completely and u put in a block off plate.

Worst case I'll send u my tune..... you should be sweet adding my tune on your ranger considering u have slightly same turbo....if anything your car will be low on power but a super clean burn and no smoke

[email protected]

[Aus_spec_ranger]

Send me your tune I would love to compere it to mine....I think your correct with the turbo vane closing too much causing bucking and this might of killed your turbo....I never had this issue at all....tuned my car at 17,000km.....now I have 124,000km....turbo sounds in very good condition by hearing it spin a long time when I shut it off. I also have E gR and dpf off.....egr off will never cause this....unless it was never turned off completely and u put in a block off plate.

Worst case I'll send u my tune..... you should be sweet adding my tune on your ranger considering u have slightly same turbo....if anything your car will be low on power but a super clean burn and no smoke

[email protected]

[JaegerWrenching]

Bucking is typically caused by hitting the turbos surge line. Hence the name surge line.

[Huskydog78]

Thanks for reply guys.
Long story here. Was using a reputable master tuner initially who turned out some good numbers but they couldn't resolve the bucking.
Next dyno workshop were confident they could sort it but still same problem, low load light/trailing throttle bucking. They suggested it was common for the 2016s with manual trans to do it.
@JaegerWrenching it doesnt sound at all of compressor surge when its bucking, and no boost peaks evident in logs or watching gauge. Tacho needle jumps around a lot though. MAF generally always looks a little lumpy but i have nothing to compare to. Exhaust note at the tailpipe at idle has a weird hiss to it that i always thought a bit odd. Intake is low restriction with big airbox inlet and oiled foam filter.
@Aus_spec_ranger yeah i can send you the hpt file for comparison. Its cost a bloody fortune to get this far so if it can be of any help to anyone then great!
Cheers

[CamTom]

I'm not familiar with your vehicle's specifics, but I've got some experience with low load bucking in a gasser. Try pulling some timing from that area. Doing that plus fattening the mixture a little worked on an LS1.

[happyhallsy8]

Happy to have a look if you'd like to send?

What year? Mines 2012 PX no DPF.

[happyhallsy8]

Thanks for reply guys.
Long story here. Was using a reputable master tuner initially who turned out some good numbers but they couldn't resolve the bucking.
Next dyno workshop were confident they could sort it but still same problem, low load light/trailing throttle bucking. They suggested it was common for the 2016s with manual trans to do it.
@JaegerWrenching it doesnt sound at all of compressor surge when its bucking, and no boost peaks evident in logs or watching gauge. Tacho needle jumps around a lot though. MAF generally always looks a little lumpy but i have nothing to compare to. Exhaust note at the tailpipe at idle has a weird hiss to it that i always thought a bit odd. Intake is low restriction with big airbox inlet and oiled foam filter.
@Aus_spec_ranger yeah i can send you the hpt file for comparison. Its cost a bloody fortune to get this far so if it can be of any help to anyone then great!
Cheers

That exhaust note hiss is identical on mine with the foam filter.