Let's discuss Smarty rail pressure settings

[atlas59]

I thought since the torque management thread I started got an ok discussion going that maybe we could look a little deeper into the rail pressure settings.....

So what are we actually manipulating with the rp settings.....obviously rp but how is smarty doing it? can the cp3 be manipulated electronically to up the pressure....can the fca be manipulated electronically to up the pressure....or is the rp setting actually manipulating the injectors to change how much pressure it takes to fire them.....
I have not played with the rp settings at all so I have not been able to see what driving characteristics change when the rp settings change....Since i have not used the rp settings I do not know if you can actually see higher numbers or lower numbers on rp gauges.

[WyoMike6.7]

To the top, I am curious as well.
Also curious as to what the timing does as far as performance.

[atlas59]

i had planned on starting a timing thread, but i thought that maybe rail pressure and smarty rp settings had more to discuss.... but i guess i was wrong.

[atlas59]

btt

I am would like some insight on this if anyone cares to share what they know before I go find out

[dirtmovr]

maybe its a big SECRET I am curious also

[atlas59]

It must be a big secret. Well since I can't get anyone to spill the secret I am just going to post what I think about it and go from there.


I have not changed RP settings on smarty so I do not know if it increases pressure or decreases it. i would only imagine it increases pressure. What I want to know is how it is doing this. I know the secret is not in the rail. Since there is nothing electronic about the rail except the rp sensor I feel comfortable in suggesting that smarty i not directly manipulating the rail. So that leaves injectors and cp3....... I think I hear helicopters and see black suits with MADS badges at my front door.

So is the cp3/fca sending more fuel to achieve higher rp or are the injectors being told to not fire until a higher pressure is achieved?

[Shibbyutman]

If you have a rail pressure gauge you can probably make the analysis by yourself, but here's the long and the short of how it's done on the 5.9 (from my observations with a RP gauge anyway, others may have differing stories but this is mine and I'm stickin' to it )

As you should know the rail pressure isn't constant across the rev range and throttle load of the engine. It has it's own map printed out in the ECM and it can be altered just as timing and duration can be. One way to inject more fuel is to increase the pressure same duration of pulse will inject more fuel if it is at higher pressure. With that in mind I believe the smarty takes the stock curves and reindexes them down a bit so idle pressure is the same, but as the load/RPM goes up the pressure rises sooner. (the higher the # in the smarty, the more advance it gives) I think they also do raise the max pressure a bit on the 5.9, but again I don't know about the 6.7. The raised max level would take the reindexed curves and add more pressure in the higher load/rpm where it would have previously topped out.

The amount of fuel commanded by the ECM is controlled by the FCA, the lower the duty cycle of it, the more fuel is passed through, the more fuel that is passed through the FCA the pressure goes up in the pump/rail.

[bthanks]

I believe it to act like the mp-8 or like a boost fooler etc etc, it changes what the computer feels the maximum top pressure can be. Thus instead of the computer shutting her down at 26K psi it will allow 27k or 28k psi before it backs it down. The numbers are not a real number just an example. Anyways the mp8 manipulates the signal that the rail sensor is letting the ecm see so therefor it allows more pressure to be made with the ecm thinking all is golden. Basicly the smarty does the same thing but it does it at the ecm.

[dirtmovr]

Originally Posted by Shibbyutman

If you have a rail pressure gauge you can probably make the analysis by yourself, but here's the long and the short of how it's done on the 5.9 (from my observations with a RP gauge anyway, others may have differing stories but this is mine and I'm stickin' to it )

As you should know the rail pressure isn't constant across the rev range and throttle load of the engine. It has it's own map printed out in the ECM and it can be altered just as timing and duration can be. One way to inject more fuel is to increase the pressure same duration of pulse will inject more fuel if it is at higher pressure. With that in mind I believe the smarty takes the stock curves and reindexes them down a bit so idle pressure is the same, but as the load/RPM goes up the pressure rises sooner. (the higher the # in the smarty, the more advance it gives) I think they also do raise the max pressure a bit on the 5.9, but again I don't know about the 6.7. The raised max level would take the reindexed curves and add more pressure in the higher load/rpm where it would have previously topped out.

The amount of fuel commanded by the ECM is controlled by the FCA, the lower the duty cycle of it, the more fuel is passed through, the more fuel that is passed through the FCA the pressure goes up in the pump/rail.

Well they must raise the rp on the 6.7 because I got a code last night POOOf for the pressure relief valve actuated. They got the low pressure code, POO87 and P1011. I do not have my rp gauge installed yet so I do not know exactly what is done.

[Shibbyutman]

for the record, what settings where you running at the time of said codes? (it may allow others to avoid popping their relief at an in opportune time)

[atlas59]

Well I feel better that I was at least on the right track. It makes better sense that the cp3/fca is raising the pressure. Will it raise cylinder temps? Will the added pressure and more fuel that is being delivered reduce cylinder temps?

[corey08cummins]

how much pressure is to much pressure in the rail for the injectors to handle?