Power Problem with FM260

[gait]

just tilted the cab and had a look at my FG. I think the guy that wrote the manual must have been dreaming.

At least now I know why the actuator arm has a kink in it.

The actuator is nicely sealed so no real chance of messing with the spring. Sorry for red herring.

Amesz thingy would work! The adjustable arm also would work. Both shift the set point.

Fascinating stuff!

Having now read my (FG) manual more thoroughly I guess I'd also want to know in what test conditions to expect the 22 psi.

 

[gait]

just tilted the cab and had a look at my FG. I think the guy that wrote the manual must have been dreaming.

At least now I know why the actuator arm has a kink in it.

The actuator is nicely sealed so no real chance of messing with the spring. Sorry for red herring.

Amesz thingy would work! The adjustable arm also would work. Both shift the set point.

Fascinating stuff!

Having now read my (FG) manual more thoroughly I guess I'd also want to know in what test conditions to expect the 22 psi.

 

[kerry]

Depending on which FG you have, you probably won't see 22psi. That threat on Ih8mud which I linked says that the 4DB4 engine has a pop off valve set at 15psi.

Ooops, you may be referring to the FM. I'd expect to see the highest boost at highest rpm's up a hill with a heavy load.

 

[gait]

...
Amesz thingy would work! The adjustable arm also would work. Both shift the set point.
..

sorry about the double post. A bit slow from Nepal.

Even worse, a senior moment and my edit didn't work.

I meant to say Amesz thingy would work. I'm struggling with how an adjustable arm would effect the set point.

 

[charlieaarons]

John,

the link to the little blue device i posted earlier, is for that exact application. its a manual boost controller. you would put it in the actuator line, then adjust to the boost you want (in this case 22psi). it works by a teeny tiny hole that bleeds out excess pressure, up to the setpoint, after that air pushes past the spring and into the actuator.
im still not convinced that the turbo is the real source of the power loss. as i have said, if it was getting the same fuel, but 18% less air (due to say a wastegate malfunction) then it would just run 18% richer... but would make similar power figures.

That was the point of my post. If there is a an inlet pressure sensor, the signal would go to the ECU which would adjust fuel injection downwards to compensate for decrease boost. Otherwise, as in your example, EGT would increase due to decreased air.

Charlie

 

[JRhetts]

sorry about the double post. A bit slow from Nepal.
Even worse, a senior moment and my edit didn't work.
I meant to say Amesz thingy would work. I'm struggling with how an adjustable arm would effect the set point.

gait

Yes, an adjustable arm would work.

Andrew/Amesz00

Thanks for posting again re the Turbosmart device. I spent some time yesterday noodling how to adjust pressure on the actuator side so as to adjust pressure over on the intake manifold side.





John

 

[westyss]

John, I have heard of "kinugawa waste gate actuators" not sure where they come from but I have seen them mounted onto Isuzu engines.

 

[westyss]

Also, if the actuator fails, will the actuator fail in the safe manner, ie. open position as opposed to closed and further damaging the engine with over boost? I think that would be the smart way to arrange it, no?


Amesz, thanks for the explanation for EGT.

 

[JRhetts]

Also, if the actuator fails, will the actuator fail in the safe manner, ie. open position as opposed to closed and further damaging the engine with over boost? I think that would be the smart way to arrange it, no?

From what I can tell, probably not. Unless the spring fails [as opposed to the diaphragm] the waste gate valve should remain closed rather than open, potentially allowing excess boost to go undumped.

On the other hand, the ECU has a turboboost sensor at the intake manifold, and if this registers a too high voltage then the ECU puts the whole system into 'limp' mode, saving the engine from over boost harm. I know this system is working on my motor, as I have thrown a number of #54 turbo over boost codes while doing various tests to find a reliable solution.

John

 

[kerry]

Also, if the actuator fails, will the actuator fail in the safe manner, ie. open position as opposed to closed and further damaging the engine with over boost? I think that would be the smart way to arrange it, no?


Amesz, thanks for the explanation for EGT.

Not necessarily. I think that's why the FG has the 15psi overboost blow off valve at the back of the intake manifold.

 

[kerry]

Not sure if the 4DB4 can go into limp mode? Does anyone know? If it does, is there any Viagra available to resolve it?

 

[westyss]

Not necessarily. I think that's why the FG has the 15psi overboost blow off valve at the back of the intake manifold.

So kerry are you saying that the boost in the FG will be limited to 15psi? When John was stating he was not getting the rated 24psi boost I was a bit surprised as I had read somewhere that the boost was 16psi? So my initial reaction was that the boost that the Mitsu mechanics found was normal, did I miss it somewhere that the FM turbo is confirmed to be 23-24psi

 

[kerry]

So kerry are you saying that the boost in the FG will be limited to 15psi? When John was stating he was not getting the rated 24psi boost I was a bit surprised as I had read somewhere that the boost was 16psi? So my initial reaction was that the boost that the Mitsu mechanics found was normal, did I miss it somewhere that the FM turbo is confirmed to be 23-24psi

Yes, the 4DB4 is limited to 15 psi by that pop off valve but standard boost on the 4DB4 is significantly less than that I think. If you read the link to the IH8MUD thread (written by a member of this forum also) the numbers are discussed there. I think the standard boost on a 4DB4 is around 10-12psi. Not sure about the figures on the FM.

Boost gauge on my 6.5GM never hits 10psi.

 

[JRhetts]

So kerry are you saying that the boost in the FG will be limited to 15psi? When John was stating he was not getting the rated 24psi boost I was a bit surprised as I had read somewhere that the boost was 16psi? So my initial reaction was that the boost that the Mitsu mechanics found was normal, did I miss it somewhere that the FM turbo is confirmed to be 23-24psi

Yves

I think I can set some numbers straight.
the factory turboboost specs are different for the FG and FM

from the FG 2005-2007 manual, boost limit is 67.8 kPa {20 in. Hg, 509 mmHg} /3100 rpm
from the FM 2005-2007 manual, boost limit is 73 kPa {21.6 in.Hg, 545 mmHg} /3180 rpm

[As an aside, it is interesting to note that the intercooler test pressures are also different. While the turbo boost is higher in the FM, the intercooler test pressure is higher in the FG. FG≥29 psi, FM≥22psi; what do we make of that?]

John

 

[kerry]

Just to be clear, I think the FG figures from 2005-2007 are not the figures for a 4DB4 engine but a later model engine. My figures apply to my USA 99FG with the 4DB4.

Those intercooler numbers are weird.