Timing between Pilot and Main event

[B00STJUNKY]

Man, this is frustrating...

If that preface didn't give it away, the theory turned out to be a dud.

A static "Adder" value of 5 allowed pilot pulse to function as normal at idle and very light load where main timing is below 1* (give or take), but any time you start getting up in the RPMs or put a bit more fuel to it with the skinny pedal, commanded main timing of course would increase, and pilot pulse would drop out.

Another weird thing is that pilot timing and pilot mm3 still log as if it's active, although now that I have set the adder table to a value of 5, logged pilot timing no longer follows the base table. It seems to be adding as much as 20* on top of the base table, and no idea where it's coming from.

For example, commanded idle pilot timing base table is 12.75*, and all the varying density tables are currently set the same. Adder is set to 5* static, Coeff is set to 1.0 static. But logged pilot timing is reading 23*, while main timing is at -2.3*. 23 (pilot) - -2.3 (main) = 25.3* BMI.

25.3 (BMI) - 12.75 (base table) = 12.55* added to base. Where the hell is all that extra timing coming from???

It would sure be cool to pick the brain of a Cummins Calibration engineer right about now to find out what the actual definitions and functions of these tables really are...

[Kill]

That bias only applies to the rail pressure adder table, all the other ones seem to follow the table values. I'm predicting the 5* limit will shut pilot off between 1500 and 2000 rpms pending on what the pw commanded is. Damn, wasn't quick enough lol

[Kill]

Set the adder table to 10 across the board, put the coefficient to 8 and see if pilot timing follows the base table.

[B00STJUNKY]

That bias only applies to the rail pressure adder table, all the other ones seem to follow the table values. I'm predicting the 5* limit will shut pilot off between 1500 and 2000 rpms pending on what the pw commanded is. Damn, wasn't quick enough lol

Mind expounding on how you came to that prediction?

Also, where do you suppose all this extra timing is coming from? What am I missing here?

[B00STJUNKY]

Set the adder table to 10 across the board, put the coefficient to 8 and see if pilot timing follows the base table.

K, I'm going to give that a shot. But in my finite mind, doesn't that imply that I'm adding 10* across the board, multiplied by a coefficient of 8, or in other words, adding 80* across the board?

By the way, I'm no longer running a static base table, instead I've reverted to a dynamic base table where all the various density tables are identical to the base. I mention this because I'm not sure if your 10 x 8 suggestion was specific to having a static 20* base table. My dynamic base table ranges from as low as 10* and as high as 25*, just for reference.

[Moparmatty]

Man, this is frustrating...

If that preface didn't give it away, the theory turned out to be a dud.

A static "Adder" value of 5 allowed pilot pulse to function as normal at idle and very light load where main timing is below 1* (give or take), but any time you start getting up in the RPMs or put a bit more fuel to it with the skinny pedal, commanded main timing of course would increase, and pilot pulse would drop out.

Another weird thing is that pilot timing and pilot mm3 still log as if it's active, although now that I have set the adder table to a value of 5, logged pilot timing no longer follows the base table. It seems to be adding as much as 20* on top of the base table, and no idea where it's coming from.

For example, commanded idle pilot timing base table is 12.75*, and all the varying density tables are currently set the same. Adder is set to 5* static, Coeff is set to 1.0 static. But logged pilot timing is reading 23*, while main timing is at -2.3*. 23 (pilot) - -2.3 (main) = 25.3* BMI.

25.3 (BMI) - 12.75 (base table) = 12.55* added to base. Where the hell is all that extra timing coming from???

It would sure be cool to pick the brain of a Cummins Calibration engineer right about now to find out what the actual definitions and functions of these tables really are...

The pilot timing tables work as labeled.

(Coefficient x adder) + pilot timing table = actual pilot timing

(1 ? 5?)+20?=25?

[Kill]

Mind expounding on how you came to that prediction?

At 1500 rpm each degree of crank rotation takes 125us, multiplied by 5 that gives you a 625us injection window for pilot, but you have to subtract the 250us min time between pilot and main. This gives you enough time for a 375us pulse. At 2000 rpm each degree of crank rotation takes 83.333us, multiplied by 5 that gives you a 417us injection window for pilot, subtracting the 250 minimum nets you enough time for a 166us pulse. I figured your pilot PW would be between those two values.

[B00STJUNKY]

The pilot timing tables work as labeled.

(Coefficient x adder) + pilot timing table = actual pilot timing

(1 ? 5?)+20?=25?

Did you read my post? My base table was not set to 20. It was set to 12.75 in that example. I was no longer running a static base table at that point.

[Kill]

K, I'm going to give that a shot. But in my finite mind, doesn't that imply that I'm adding 10* across the board, multiplied by a coefficient of 8, or in other words, adding 80* across the board?

By the way, I'm no longer running a static base table, instead I've reverted to a dynamic base table where all the various density tables are identical to the base. I mention this because I'm not sure if your 10 x 8 suggestion was specific to having a static 20* base table. My dynamic base table ranges from as low as 10* and as high as 25*, just for reference.

If it is a limiter, it is setting the limiter to 80 degrees where you should never hit it. You are pretty much going through the same routine I did a few days ago. With those settings, and a flat 20* pilot timing table my truck would stay at 20* most of the time besides cruising it would still drop to around 12 or 13* for some reason. I quit messing with it because I decided there was something else affecting it that we don't have access to, kind of like the misfire minimum timing for the main event.

[Moparmatty]

Did you read my post? My base table was not set to 20. It was set to 12.75 in that example. I was no longer running a static base table at that point.

Alright. Can you post a screen shot of your log at an rpm you like to figure out what the pilot timing is doing? Also need a screen shot your you tune showing the pilot timing, pilot IAT coefficient and pilot IAT adder tables.

[B00STJUNKY]

At 1500 rpm each degree of crank rotation takes 125us, multiplied by 5 that gives you a 625us injection window for pilot, but you have to subtract the 250us min time between pilot and main. This gives you enough time for a 375us pulse. At 2000 rpm each degree of crank rotation takes 83.333us, multiplied by 5 that gives you a 417us injection window for pilot, subtracting the 250 minimum nets you enough time for a 166us pulse. I figured your pilot PW would be between those two values.

Man, my head is spinning... The math is understandable, that's not where I'm getting confused. I'm confused because I have one person saying the tables function as they're defined, meaning that they add degrees of timing on top of the base table. But what you're suggesting here (or seem to be suggesting) is that these tables are not adding on top of the base table, but rather, are defining the maximum duration that pulse is allowed to be active.

Am I understanding that correctly?

Or is it that you're suggesting the "Adder" table is really a "Maximum" degrees of pilot table?

[Kill]

Man, my head is spinning... The math is understandable, that's not where I'm getting confused. I'm confused because I have one person saying the tables function as they're defined, meaning that they add degrees of timing on top of the base table. But what you're suggesting here (or seem to be suggesting) is that these tables are not adding on top of the base table, but rather, are defining the maximum duration that pulse is allowed to be active.

Am I understanding that correctly?

It's not defining the maximum pulse, it's defining the maximum pilot timing. The pulse only tells me if it will shut off pilot because of a too small of an injection window. I know for a fact on my truck that the pilot timing adder table does not add to my pilot timing base table. The 04.5 up trucks may be different but so far from what I have seen I believe they work the same way, I just don't have a truck to test it on.

[B00STJUNKY]

Alright. Can you post a screen shot of your log at an rpm you like to figure out what the pilot timing is doing? Also need a screen shot your you tune showing the pilot timing, pilot IAT coefficient and pilot IAT adder tables.

Base Table.png

Discrepent_Pilot_timing.png

[B00STJUNKY]

It's not defining the maximum pulse, it's defining the maximum pilot timing. The pulse only tells me if it will shut off pilot because of a too small of an injection window. I know for a fact on my truck that the pilot timing adder table does not add to my pilot timing base table. The 04.5 up trucks may be different but so far from what I have seen I believe they work the same way, I just don't have a truck to test it on.

Yeah, sorry... I had edited my previous post after re-reading yours to see if it was actually that you were suggesting it was a maximum degrees table.

I think you may be on to something.

[B00STJUNKY]

Alright. Can you post a screen shot of your log at an rpm you like to figure out what the pilot timing is doing? Also need a screen shot your you tune showing the pilot timing, pilot IAT coefficient and pilot IAT adder tables.

Here's the idle example I had explained previously:

idle_discrepency.png

Base Table.png

[Kill]

Here is a log and the tune from when I was playing around with this. It still didn't do what I wanted it to, but lets see what you guys think.

[Moparmatty]

Base Table.png

Discrepent_Pilot_timing.png

It shows right in your log what is controlling your pilot timing.

Post a screen shot of your ECT coefficient and adder tables.

[B00STJUNKY]

It shows right in your log what is controlling your pilot timing.

Post a screen shot of your ECT coefficient and adder tables.

Uhm... I did... Didn't I?

[Kill]

Base Table.png

Discrepent_Pilot_timing.png

The fact that pilot got turned off supports what I have been saying, but your log still shows 28.2* of pilot timing...weird.
I wonder where it is getting that number, even if you add the 5 from the adder to the base table its still not right.

[B00STJUNKY]

You posted the IAT tabs like I asked.

Now I'd like to see your pilot ECT tables.

Those are ECT x IAT tables. I don't have individual IAT and ECT tables. They're combined.