B3350 Turbo Boost Pressure - Solved!

[90cummins]

Wastegates are used for various reasons.
1 it prevents over boost to protect the engine and/or turbo.
excessive boost can over speed the turbo causing major damage to engine.
2 it’s part of the emissions package.
3 it allows a smaller turbo to be installed which allows the engine to build boost (torque) at lower engine speeds (tractor use) while preventing over boost when engine is at max speed & power.
It is possible that the fuel rate is less than factory specifications.
If that is the case you will never build boost

If you were to install a turbo on an engine that was not originally equipped with one you would see little if any horsepower increase.
In order to build boost you must increase the fuel rate by adjusting the injection pump. More fuel = more boost = more power.
If your turbo was defective I would suspect that at full speed full load your engine would be rolling some serious black smoke. Is your exhaust clean or hazy or black?
I installed a wastegated turbo on my Ford 1720 years ago. I wired the waste gate closed and increased the fuel rate and top engine speed.
What use to be barely adequate (in my opinion) is now a torque monster that will roll coal if allowed to lug. It will build 10 lbs boost when pushed hard.
I mention this only to bolster my opinion. 90cummins

 

[Travis616]

I'm wondering if Kubota limits fuel rack travel to de-rate the engine? I originally thought they would lower rpm but after thinking about it I'm not getting any smoke under full load and it's maxing out at 4psi boost. I took some stuff apart to get a better look at the wastegate actuator and it takes exactly 8psi for it to move. Going to get it to the dealer and see what the laptop shows! I have been wondering if it would be worth it to make some stuff up that I could use my land and sea snowmobile dyno as a small tractor dyno? I would need to speed up the input into the absorber and reverse the direction but I think it could be done fairly easily with chain/sprockets for all the hp I'm looking at

 

[Jerry/MT]

I'm wondering if Kubota limits fuel rack travel to de-rate the engine? I originally thought they would lower rpm but after thinking about it I'm not getting any smoke under full load and it's maxing out at 4psi boost. I took some stuff apart to get a better look at the wastegate actuator and it takes exactly 8psi for it to move. Going to get it to the dealer and see what the laptop shows! I have been wondering if it would be worth it to make some stuff up that I could use my land and sea snowmobile dyno as a small tractor dyno? I would need to speed up the input into the absorber and reverse the direction but I think it could be done fairly easily with chain/sprockets for all the hp I'm looking at

If lack of power is the problem and the air intake system is unrestricted then have you considered that inadequate fuel delivery could be the problem? check out the engine fuel delivery system.
All the boost in the world is no good if you don't have the extra fuel to go along with the extra airflow. Remember it takes fuel at the right time, air, and compression to make power in a diesel.

 

[Doughknob]

Yeah, no idea what pressure should be. But even 8 seems low. My car makes 15-18psi nominally. The smaller the nominal boost, the less economically feasible it is to even build that engine.

 

[ZetorSteve]

You really need a service manual. Don't go chasing a problem that does not exist. Are your new Holland's the same transmission as the Kubota?

You will not have any black smoke out of the exhaust on the Kubota due to the DPF catching all the soot.

 

[Travis616]

If lack of power is the problem and the air intake system is unrestricted then have you considered that inadequate fuel delivery could be the problem? check out the engine fuel delivery system.
All the boost in the world is no good if you don't have the extra fuel to go along with the extra airflow. Remember it takes fuel at the right time, air, and compression to make power in a diesel.

I believe it is a fuel delivery issue, one that's controlled by the ecm though. Replaced the dpf pressure sensor with an aftermarket one and it was actually starting off negative and then going to 0psi when the throttle was wide open. I have an emulator that I'll try for now and see about getting a new sensor.

 

[Travis616]

Yeah, no idea what pressure should be. But even 8 seems low. My car makes 15-18psi nominally. The smaller the nominal boost, the less economically feasible it is to even build that engine.

With the wastegate opening at 8psi (using a handheld pump) I would assume that should be loaded/working operating pressure

 

[Travis616]

You really need a service manual. Don't go chasing a problem that does not exist. Are your new Holland's the same transmission as the Kubota?

You will not have any black smoke out of the exhaust on the Kubota due to the DPF catching all the soot.

I have the factory Kubota service manual however it isn't very in depth in the things I would like to know. The dealers around here aren't sure what typical boost is because it isn't published was what I was told..they're all hst transmissions with very similar top speeds so should perform very closely if all is correct. My dpf will let smoke out after some work was done..

 

[Travis616]

Had the dealer come out to check/clear codes, which is a story in itself, but found that the dpf pressure sensor was actually reading a vacuum instead of pressure so sensor is faulty. Had him reset the soot load in the ecm and then hooked up the dpf emulator after he left. It ties into the CAN high & low, keyed power, ground, dpf pressure, and all three exhaust temp. I didn't bother with the exhaust temp for now but hooked the rest up and my mil light is now out, regen lights are out, and boost is up to 8psi under load. Just some info for anyone who might be thinking of gutting the dpf that the emulator would work to fool the ecm..