it's scary what can be found in an ECM

[Delinquent]

man, I'm a twelve valve guy that has never messed with any EFIlive. What I'm about to do will make me look dumb but:


In my mind, this is what you guys are trying to say:

You alter the duty cycle (time) to try and give the rail the amount of fuel it needs before the FCA valve closes, then the PId reads pressure and will adjust the duty cycle of the FCA accordingly to maintain the proper pressure as set in the Tables.

 

[Smoken Gun]

This is a heated debate, but a good one. I enjoy learning about this stuff, as much as I can with my limited knowledge base on the subject that is. Thank you for putting this info out there guys! One of the best threads on here in a while IMHO.

And damn those boxer tuner tables looked nasty...

 

[Big Swole]

Tacos anyone??

 

[Schrowang]

Tacos anyone??

nom nom nom

 

[homewrecker]

It sounds like you two are saying the same thing, just using different terminology. Lol.

tapatalking from droidx

 

[triton]

I'm new to this dudes so I may be off base a little with this but, here's how I see it..... if I'm wrong, please correct me.


A PID is basically a fancy intelligent "regulator" that's not infalable. You set your psi in the base table where you want it. Drive the truck and over time the PID learns where the averages are from the values you set in the table ( commanded ) and the actuals.

So, in a sense it is a limiter because you can adjust it's values to see what you want it to see..... through the roof or nothing.

It seems, you both are right and basically talking about the same thing... just using different terminalogy. <<<< I had the exact same thing in mind as homewrecker

That 36K can mean everything and be very dangerous if the limiters and PIDs were adjusted to let the truck get there.

The thing about the tune in question is, it's probably like that in most box tuners. No, the values didn't need to go to 36K cause they were never gonna get there in the first place. But, putting them that high enable the psi to go as high as the PIDs and/or limiters would let them. Who ever wrote that tune may not have known exactly what the limit was or it might not have been accessible to them at the time ???? It still means that at WOT, the truck is looking for that psi..... luckily for those writting box tunes, the limiters are there or there'd have been lots more blown motors.

 

[Cummin-a-long]

We're saying the same thing.

So, like I said, we're both seeing the same thing, you just seem to think that duty cycle is an estimation of volume, when its not. Is it allowing a greater VOLUME of fuel to flow with increased duty cycle? Yes, thats a given. If the valve is open longer, you get a greater volume of fuel through it.

It sounds like you two are saying the same thing, just using different terminology. Lol.

It seems, you both are right and basically talking about the same thing... just using different terminalogy. <<<< I had the exact same thing in mind as homewrecker

In my mind, this is what you guys are trying to say:

You alter the duty cycle (time) to try and give the rail the amount of fuel it needs before the FCA valve closes, then the PId reads pressure and will adjust the duty cycle of the FCA accordingly to maintain the proper pressure as set in the Tables.

Ya think...... :lolly:

Drama, drama, drama.....

*bdh*

 

[MotoCraneGuy17]

The base table if it were to be set perfectly would perfectly match the volume of fuel required to maintain pressure at a specific mm3...(oh yes again volume fuel).

You do know mm3 is just a reference the ECM uses right? A reference to command 'X' amount of pressure and time to meet the specific requirements that the engine is being demanded.

 

[Flashscan]

A PID is basically a fancy intelligent "regulator" that's not infalable. You set your psi in the base table where you want it. Drive the truck and over time the PID learns where the averages are from the values you set in the table ( commanded ) and the actuals.

The Rail Pressure P.I.D (not to be confused with the term PID used in scantool terminology) is very similar to how a cruise control works. You set the desired cruise MPH (say 70), on the flat it's nice and easy for the cruise to maintain the speed with minimal to no adjustments needed. But then if you come to a hill the cruise control has to do something to maintain your desired speed, first it will try pushing the pedal down more, if that fails it might drop back a gear, all the while it's trying to maintain that 70MPH, once you reach the top then start to go down the hill it has to do the opposite, lift the throttle, maybe drop back a gear again for some engine braking. That is known as P.I.D control, trying to maintain a set value through trial and error. It doesn't learn as such (though some can), it just spends it's whole life adjusting things.

Now imagine you could enter in to your cruise control via a keypad your desired speed, you put in 230 MPH (thinking about that 36K rail pressure value in discussion), it's pointless, the cruise control will forever be stuck trying to get to 230MPH and do nothing else, including as you coast down a hill it will keep accelerating. So this is why the people that design these computers have limiters built in, just to make sure for some reason the ECM doesn't have the chance to calculate out some crazy number and try to apply it.

 

[triton]

The Rail Pressure P.I.D (not to be confused with the term PID used in scantool terminology) is very similar to how a cruise control works. You set the desired cruise MPH (say 70), on the flat it's nice and easy for the cruise to maintain the speed with minimal to no adjustments needed. But then if you come to a hill the cruise control has to do something to maintain your desired speed, first it will try pushing the pedal down more, if that fails it might drop back a gear, all the while it's trying to maintain that 70MPH, once you reach the top then start to go down the hill it has to do the opposite, lift the throttle, maybe drop back a gear again for some engine braking. That is known as P.I.D control, trying to maintain a set value through trial and error. It doesn't learn as such (though some can), it just spends it's whole life adjusting things.

Now imagine you could enter in to your cruise control via a keypad your desired speed, you put in 230 MPH (thinking about that 36K rail pressure value in discussion), it's pointless, the cruise control will forever be stuck trying to get to 230MPH and do nothing else, including as you coast down a hill it will keep accelerating. So this is why the people that design these computers have limiters built in, just to make sure for some reason the ECM doesn't have the chance to calculate out some crazy number and try to apply it.

Thank you for the great laymen explanation! Sounds like I'm some what on the right track. I figured because of the PID using 3 variables to determine what to do, one of the 3 was a average it fell back to so it didn't have to work as much.

So, in this case.... how is the fuel psi PID affecting the table ?

 

[Joesixpack]

In terms to pressure regulation and the PID I can't explain it better than I already have.

The base duty cycle is ABSOLUTELY the best estimation of volume flow PERIOD. Bosch and others call it "Estimated duty cycle" in reference to fuel volume....:nail:

The base table if it were to be set perfectly would perfectly match the volume of fuel required to maintain pressure at a specific mm3...(oh yes again volume fuel).

NOW in the real world you can never perfectly match that, so that why we have a PID to track pressure and make corrections to VOLUME FLOW to maintain pressure.

TO DO THIS, the PID directly uses the values in the base table as a reference and to more quickly and precisely make adjustments.

WHEN you are working the pressure regulator base table you absolutely are working with volume whether you know it or not.

Compd....educating the nOOb's the hard way since.......LOL Hey thats what needs to be up top...LOL

You do know mm3 is just a reference the ECM uses right? A reference to command 'X' amount of pressure and time to meet the specific requirements that the engine is being demanded.

Ummm.... You do know mm3 IS a reference to fuel VOLUME that the ecm uses right????
Now think about what pressure vs time gets us????

It sounds like you two are saying the same thing, just using different terminology. Lol.

tapatalking from droidx

After re-reading his posts this morning not even close.....but he'll come around......:stab:

 

[Cummin-a-long]

So, in this case.... how is the fuel psi PID affecting the table ?

Ty, which table are you referring to?

 

[triton]

Ty, which table are you referring to?

this 36K table we're taking about. I wanted to see what he though about what you guys have said. If anyone would know, I would think Flashscan would. Sorry forget your name.... Greg, Gary

 

[Cummin-a-long]

After re-reading his posts this morning not even close.....but he'll come around......:stab:

Mmmm....yeeeeeah, NO.

You go on and keep thinking that the FCA's duty cycle will over ride what the ECM is being told to do in the tables.

bif

Like I said, if you want to test your theory, I'll gladly build ya 2 tunes that have IDENTICAL values, except the pressure limiter. You go ahead and load that on your truck and see what happens when it's allowed to command 36k+ PSI.

No FCA duty cycle is going to keep you from needing new injectors.

The ONLY reason....the one and only reason to adjust FCA duty cycle is if you're draining the rail. THAT's IT. The ONLY reason.

IT's....A...."F'n".....VALVE! It simply does what it's told. Open more / open less....THAT's IT.

 

[Joesixpack]

Ooof.....last grapple full of posts had nothing to do with this 36k table.....were on the Pressure regulator base duty table......


And after that last post, I wouldn't use a "doghouse diesel" tune for no money as he has a complete lack of understanding of how the pressure regulator works.

Pressure regulation is closed loop control unless there is a sensor or actuator failure.

Another bought efi yesterday and I R TUNER come lately.....:nail:


Flashscan has a great analogy I"ll expand on when I'm free today.......

 

[Cummin-a-long]

this 36K table we're taking about. I wanted to see what he though about what you guys have said. If anyone would know, I would think Flashscan would. Sorry forget your name.... Greg, Gary

Ty, the values in that table are the "goal". When mm3 value and RPM's are in those ranges, the ECM is commanding that pressure.

To keep that pressure, the PID controller commands adjustments to the FCA to increase or decrease fuel.

THIS is where the FCA duty cycle comes into play. As long as the FCA's duty cycle is high enough, it'll meet the demand being commanded by the ECM. If the duty cycle isn't high enough, you'll see the rail pressure fall off. To correct that, you modify the duty cycle (or you simply need a larger pump if it just can't keep up).

 

[Cummin-a-long]

Ooof.....last grapple full of posts had nothing to do with this 36k table.....were on the Pressure regulator base duty table......


And after that last post, I wouldn't use a "doghouse diesel" tune for no money as he has a complete lack of understanding of how the pressure regulator works.

Pressure regulation is closed loop control unless there is a sensor or actuator failure.

Another bought efi yesterday and I R TUNER come lately.....:nail:

Yeah, you do that chief.

I won't lose sleep over it.

You wanna prove your theory, I gave you the choice.

If you think FCA duty cycle is ANYTHING more than telling the valve to open or close, or open longer, you're kidding yourself.

Go ahead and make you a tune that only adjusts FCA duty cycle and let me know how that works for ya.

*bdh*

 

[triton]

Ty, the values in that table are the "goal". When mm3 value and RPM's are in those ranges, the ECM is commanding that pressure.

To keep that pressure, the PID controller commands adjustments to the FCA to increase or decrease fuel.

THIS is where the FCA duty cycle comes into play. As long as the FCA's duty cycle is high enough, it'll meet the demand being commanded by the ECM. If the duty cycle isn't high enough, you'll see the rail pressure fall off. To correct that, you modify the duty cycle (or you simply need a larger pump if it just can't keep up).

Aahhh 10-4. I got that about the tables but, wasn't clear on how the PID played it's part. Thanks

You two should get into about combustion next :clap: I can only imagine the info I'd get out of a debate on that :Cheer:

 

[SINNER]

By definition a valve only controls volume. Pressure is a secondary result of the amount of substance a valve passes. Plumbing 101. LOL

 

[triton]

thing is, there's nothing in the ECM or tuning software that say..... this is the "volume" per millisecond or what ever. My understand is the FCA is told what to do based on the duty cycle it's set at. It can be called a valve, limiter, restrictor, taco, Dennis's boat.... what ever you want. It's still not "measuring" any type of volume going through it. It's just doing what it's told.