it's scary what can be found in an ECM

[SHughes]

May I interject with a possibly dumb question?

What is the output pressure of the CP3? Generally, obviously there will be differences. And is it tunable at all or simply chaged via a pump swap? And the output is ALL through he FCA? Correct?

Epically posted via Tapatalk...

 

[Cummin-a-long]

PHUCK IT, feel like I'm beating down the local retard and everyone is watching.

Dan picked it out of simple knowledge of diesel systems and controllers and actuators, not from direct experience with this system!!!

You're right everyone is watching....and you haven't proved your point....except that you're too stubborn to listen what actually is.

The system IS NOT volume based.

Unless you can show the output volume of the CP3 in each circumstance, your theory isn't valid. The ONLY thing the CP3 does is pressurize the fuel and send it to a resevoir.

 

[LReiff]

I kinda assume that's what a controller would do. Most trucks with duals probably will never see 100% away.

The control box only only splits the control signal equally. What happens if the pumps do not flow equally?

 

[triton]

The control box only only splits the control signal equally. What happens if the pumps do not flow equally?

ok 10-4. I'm forgetting about the mechanical part.

 

[Joesixpack]

WTF are you guys arguing about? You two just said the same thing with the faucet analogy... Rich said the FCA controlls pressure, which is CORRECT. Yes, this translates into fuel flow, BUT there is nowhere in the system that flow is measured. Fuel flow is calculated, thats why aftermarket pumps and injectors whack up the whole system. Im not sure what point you are trying to get across, but you are both right. The FCA allows more fuel to "flow" and increase "volume" but all it does in maintain "pressure".

Now back to what you were doing bif

OK one more crack.

Fuel flow through the metering valve or FCA can VERY well be represented and repeated and is IN FACT represented by the "Pressure regulator base duty cycle" table.

YES this table "almost" can reflect how much duty cycle the FCA needs to maintain the correct flow to meet the required mm3's commanded by the ecm.

Again, the closer this table matches the actual flow of the pump/pumps, the easier it will be for the pressure regulator to track its setpoint.

 

[zstroken]

PHUCK IT, feel like I'm beating down the local retard and everyone is watching.

Dan picked it out of simple knowledge of diesel systems and controllers and actuators, not from direct experience with this system!!!

One question I have is do you know the output of the cp3 at a certain FCA setting on the modded cp3? If so do you get max flow from the cp3 modder? Then assume that it is linear throughout the FCA range of 0-100%?

 

[triton]

May I interject with a possibly dumb question?

What is the output pressure of the CP3? Generally, obviously there will be differences. And is it tunable at all or simply chaged via a pump swap? And the output is ALL through he FCA? Correct?

Epically posted via Tapatalk...

at the risk of a complete dumb answer.....

that is dictated by what's being talked about. A modded pump will flow more but, it still has to be told how much through the FCA.

 

[LReiff]

One question I have is do you know the output of the cp3 at a certain FCA setting on the modded cp3? If so do you get max flow from the cp3 modder? Then assume that it is linear throughout the FCA range of 0-100%?

Flow will only be as linear as the flow control ports in the valve. I know this because I have modded fcas myself and have created problems that tuning could not easily correct.

 

[TheBigNasty]

May I interject with a possibly dumb question?

What is the output pressure of the CP3? Generally, obviously there will be differences. And is it tunable at all or simply chaged via a pump swap? And the output is ALL through he FCA? Correct?

Epically posted via Tapatalk...

The cp3 doesn't put out a pressure, it puts out a volume that is restricted(pressurized) up to the maximum psi the system can handle...or which is relieved via pressure regulator. This is why you have low rp, the volume of the pump is less than what is allowed through the injectors. No restriction=no pressure.

The PID is reactive based on its only means of input (feedback). The PID has to apply less "reaction" if the FCA duty cycle is already calibrated to how much volume the FCA passes in relation to how much the system uses.

 

[Cummin-a-long]

at the risk of a complete dumb answer.....

that is dictated by what's being talked about. A modded pump will flow more but, it still has to be told how much through the FCA.

Ty,

There is another control that hasn't been mentioned and that's the cascade overflow valve.

It has three functions. All are mechanical and all are PRESSURE based.

1 - regulation of fuel to lube the pump.
2 - regulation of fuel pressure supplied to the FCA.
3 - returning excess fuel to the tank.

The only thing TOLD to the FCA is "open this much".

 

[Flashscan]

Your mistaking a pressure control valve....(That is mounted on the rail instead of our mechanical relief)......With a volume control valve or "metering valve" that we have mounted to our pumps.

Sorry, I was trying to put a little water on the fire by quoting from a book written by Bosch engineers, re-reading it though I might have made things worse as they talk about pressure and flow.

 

[JWhite]

OK one more crack.

Fuel flow through the metering valve or FCA can VERY well be represented and repeated and is IN FACT represented by the "Pressure regulator base duty cycle" table.

YES this table "almost" can reflect how much duty cycle the FCA needs to maintain the correct flow to meet the required mm3's commanded by the ecm.

Again, the closer this table matches the actual flow of the pump/pumps, the easier it will be for the pressure regulator to track its setpoint.

Yes, everything you said about the table is true. Nobody said you were completely wrong, Rich is just saying how the ECM works off of pressure readings not flow, which is either "calculated" or "commanded". This is why the 6.7L ECM uses injector trim codes so that it can better calculate fuel flow...

 

[LReiff]

Ty,

There is another control that hasn't been mentioned and that's the cascade overflow valve.

It has three functions. All are mechanical and all are PRESSURE based.

1 - regulation of fuel to lube the pump.
2 - regulation of fuel pressure supplied to the FCA.
3 - returning excess fuel to the tank.

The only thing TOLD to the FCA is "open this much".

I think all here realize that modded pumps put out more flow than a stock pump, otherwise this thread wouldn't have gone as far as it has. Cascade valves are mechanical not tuneable!

 

[Joesixpack]

One question I have is do you know the output of the cp3 at a certain FCA setting on the modded cp3? If so do you get max flow from the cp3 modder? Then assume that it is linear throughout the FCA range of 0-100%?

YES! if they measured it....there might be some mismatch through control hardware however.

In reality you populate this table through experimentation comparing commanded FCA duty cycle and what is in this base table through data logs.

Flow will only be as linear as the flow control ports in the valve. I know this because I have modded fcas myself and have created problems that tuning could not easily correct.

Yes Yes Yes!!! Another example, non linear pump flow, again if you had access then you could have corrected this in the ecm.

 

[Amish Elegance]

Ok, you guys arent saying the same thing, but I think you're both right.

The system does control pressure. The end result is a desired VOLUME of fuel injected into the cylinder. This volume can be achieved by knowing how much fuel your injectors flow at a given pressure and duration. Your timing starts the duration event, you stop it x degrees or ms later. This is duration. In order to get the volume of fuel in the cylinder you want, if you know what the injector flows, you know how long its open, the only element left to calculate is... Pressure.

The goal is a volume of fuel in the cylinder. We get that from injector duration and pressure. To achieve that pressure, we vary the volume the pump produces.(with respect to volume depleted by the injectors.)

Are we all friends yet?

 

[LReiff]

I'm sure a better understanding of the PID control would have aided me as well. I'll study it some more and keep improving my skills!

 

[Joesixpack]

Ok, you guys arent saying the same thing, but I think you're both right.

The system does control pressure. The end result is a desired VOLUME of fuel injected into the cylinder. This volume can be achieved by knowing how much fuel your injectors flow at a given pressure and duration. Your timing starts the duration event, you stop it x degrees or ms later. This is duration. In order to get the volume of fuel in the cylinder you want, if you know what the injector flows, you know how long its open, the only element left to calculate is... Pressure.

The goal is a volume of fuel in the cylinder. We get that from injector duration and pressure. To achieve that pressure, we vary the volume the pump produces.(with respect to volume depleted by the injectors.)

Are we all friends yet?

I'm not denying pressure at all!!! Show me were I did?

He just didn't have an inkling of how the system actually gets there. Still repeating volume is meaningless!!!! Where is it measured!!!!!*bdh*

Included a free schooling on the whole pressure control system to boot.

Sorry, I was trying to put a little water on the fire by quoting from a book written by Bosch engineers, re-reading it though I might have made things worse as they talk about pressure and flow.

Quoting the bible....know it well and do it time to time.

 

[Cummin-a-long]

And I'm not denying volume! Obviously if there isn't sufficient volume, you won't be able to maintain pressure....at least for any usable period of time. BUT, PRESSURE is the systems control. PERIOD!

And at NO POINT have I said volume is meaningless. Not sure where Mr JSP is pulling that from. Please feel free to quote me where you found that.

As far as his "schooling" on pressure control.....uhh, no....there was no schooling involved. More like feeding an over-inflated ego. I'm more than familiar with the systems at hand.

 

[Joesixpack]

I've shown ten times now the ecm exactly has a very good idea of what volume flow our cp3 flows and this is contained in the Pressure regulator base duty cycle table. The PID for controlling pressure very heavily draws from this exact table.

Your STUCK on the closed loop PID controlling pressure, and completely ignoring the open loop feed forward term is KNOWN VALUES!!!!!

Just not going to try and beat it into your head any more.

Even non laymen to the system are picking this up, have no idea why your not catching on.

 

[triton]

well with what you guys probably consider some messed up internet back and forth.....you and others have generated a unbelievable amount of great info.

I for one would like to thank all for their input. This is better than sitting in class at a diesel school.