2800 RPM Fuel Drop-Off

[68showngo]

I've heard that there is an issue with the fuel drop-off after 2800 RPMs, but lately I haven't heard much about it.. Is there a fix for this already? Unless I've been looking at things wrong, I've got this problem too. Don't notice much when driving, but can see it when logging. Would like to get it fixed either way. I also heard something about the operating system had something to do with this. Can this simply be re-flashed or is this a more complicated fix yet? Also, where would I get the proper tune file for this?

[2007 5.9]

Beta testers are feverishly working on it....

~Les

[68showngo]

Ok just didn't want to have the issue if there was a fix already.. haven't been able to even go to the track lately anyway so it doesn't make me too big of a difference yet, but would love to fuel to 3400-3500 if there was a benefit and if it was alright on a stock truck.

[GMPX]

One of the beta testers reported back that a new table we added has cured he's fuelling drop off's at about 3,600, he's now seeing good fuel up to 4,200RPM.

[68showngo]

Awesome! Can't wait to try it out

Sent from my DROIDX using Tapatalk

[IdahoRob]

Appears to be an OS issue also. Some do it and some don't with the same tuning in simular set-ups. Only difference is OS that I can see. Continuing testing this week to weed out the problem OS's.

[68showngo]

One more question, can an OS be flashed onto another truck or am I stuck with what I have?

[IdahoRob]

Yes, you can flash in a different OS. Will have to change the vin to correct the anti-theft.

[2007 5.9]

Is the calibration id important??

That OS you posted rob, has a different cal id than my OS...

[GMPX]

Don't take this list as the be all end all, it is taken from a pdf Chrysler/Dodge stopped updating some time ago on the service website.

2006 Models:
35325833 = Auto, Mega Cab, California
35325533 = Auto, California
35325853 = Auto, Mega Cab, Federal
35325553 = Auto, Federal
35325531 = Manual, California
35325551 = Manual, Federal

2007 Models:
45325833 = Auto, Mega Cab, California
45325733 = Auto, California
45325853 = Auto, Mega Cab, Federal
45325753 = Auto, Federal
45325731 = Manual, California
45325751 = Manual, Federal

Where they have the letters is like a revision of the calibration I would guess. Eg, 45325751AG is the calibration after 45325751AF.
These numbers don't appear to have anything to do with the OS number.

[2007 5.9]

Understood...my '07 has a 5733 designation and the '06 has a 5533...except for the middle 5 being a 7 on mine...it's close.

Any forseen issues with putting a 5533 in a 5733???

[TexasCummins]

I used to have this issue and fixed it unknowingly when I got the truck up to 3,400rpm today.

I went to the injection quantity pedal position to desired fuel normal and transient graphs and changed the mm3 value for 25%, 50% and 100% values for every rpm to 200.

[TorqueDieselLLC]

ok so after fighting this same fuel cut off i have a truck fully fueling to 4300rpm which is where i have the limiter set

could not get it there using the stock tune as a base

used SW9(non-4000rpm) as a base then ran my script over it and now it spins 4300 no problem at all, even tho the SW9 base tune was not capable of the rpm

my conclusion is that there is a table that we cant see right now that the SW9 is changing that is fixing the defuel

[chizwizdiz]

ok so after fighting this same fuel cut off i have a truck fully fueling to 4300rpm which is where i have the limiter set

could not get it there using the stock tune as a base

used SW9(non-4000rpm) as a base then ran my script over it and now it spins 4300 no problem at all, even tho the SW9 base tune was not capable of the rpm

my conclusion is that there is a table that we cant see right now that the SW9 is changing that is fixing the defuel

I'm curious to see what the EFI team finds.

[comnrailpwr]

X2

Spray & Pray

[bean]

ok so after fighting this same fuel cut off i have a truck fully fueling to 4300rpm which is where i have the limiter set

could not get it there using the stock tune as a base

used SW9(non-4000rpm) as a base then ran my script over it and now it spins 4300 no problem at all, even tho the SW9 base tune was not capable of the rpm

my conclusion is that there is a table that we cant see right now that the SW9 is changing that is fixing the defuel

Through extensive testing and data logging I too have come to the same conclusion, there is a table we dont have yet. Smarty files do not cut back on desired fuel but anything EFI I have tried will start cutting it back around 2400rpms and peaks power at 2800. This would include copy and pasting every single table from a Smarty file into a fresh EFI tune.

Pretty sure its a torque limiting table, if the % of maximum TQ PID goes over 100% it will immediatly start cutting fuel. The current TQ limit table doesnt do anything, you can put it at 1 or max it out and it changes nothing.

[dansdieselp]

We have our truck full fueling to 3,600rpm, but commanded pulse width drops off starting at 2,800rpm and can really hinder the power above 3k. Is everyone else seeing this same problem? In testing we've upped the pulse time and timing and it's neither a pulse multiplier table or pulse timing limiter. It has to be a max pulse vs rpm table as another form of engine protection.

[2007 5.9]

We have our truck full fueling to 3,600rpm, but commanded pulse width drops off starting at 2,800rpm and can really hinder the power above 3k. Is everyone else seeing this same problem? In testing we've upped the pulse time and timing and it's neither a pulse multiplier table or pulse timing limiter. It has to be a max pulse vs rpm table as another form of engine protection.

To me it also seems like a uS vs rpm limiting table....weather I command 3000uS or 5000uS, it always pulls back to 2000-2200uS at 2800......but commanded mm3 stays at 145mm3 the entire pull up to 4100rpm's.

~Les

[Dmaxink]

One of my issues was the pressure duty cycle... We could see the pressure start taking its effect as the dc% was going above 28. Being able to keep that at >24% allowed me to keep pressure and hold it and kept pulse (2450) all the way up to 3800 and then it takes a drastic drop. I have a customer logging a 3450 pulse this evening and i will report back the verdict. I have him a tune with stock DC and modified DC... I'm on vacation in panama, Fl so as soon as i get back on i will post the verdict! I will say without the necessary fp table modifications not timing, desired pressure, nor any other tables have had an effect on the limiter..the only one i have found in my case has been the duty cycle which is dependant on rpm. Again, i will report back. Thanks

[MQ105]

To me it also seems like a uS vs rpm limiting table....weather I command 3000uS or 5000uS, it always pulls back to 2000-2200uS at 2800......but commanded mm3 stays at 145mm3 the entire pull up to 4100rpm's.~Les

Interesting. My Commanded volume drops above 2900 rpm, with a corresponding change in duration. At times, the duration is a lot less than what is in the table. Also, I've seen the commanded volume go as low as 70mm3 at 3200 rpm and WOT.

[2007 5.9]

Interesting. My Commanded volume drops above 2900 rpm, with a corresponding change in duration. At times, the duration is a lot less than what is in the table. Also, I've seen the commanded volume go as low as 70mm3 at 3200 rpm and WOT.

I'm running a beta sw that is due to be released soon that was focused on getting commanded mm3 to hold through the rpm band.

When it comes out, you'll be able to see what I'm talking about.

~Les

[MQ105]

Will the new stuff address the duration drop also?

[2007 5.9]

It has a little but mainly fixed the dropping mm3.

~Les

[68showngo]

Kind of sucks that I busted up my bed and lost a tail light, but I might still try some testing soon too since I'm out in the country. Hopefully this will get me a little more power. Really need to take it to the track already to compare times with the Smarty.

Is 3500 RPM the limit on a totally stock motor? That's what I've gathered from reading so far, and then you need springs for 4k, possibly a cam to get the extra power up top... I want to get springs, cam, studs, and maybe a little head work done on it one day, but don't know what 4200 RPMs would do with stock fuel system and turbo.

[68showngo]

double post

[DoghouseDiesel]

What turbo are you running?

3500 RPM's is "okay" under stock boost conditions, but really you won't see squat with that stock cam anyways. It's pretty pathetic above 2800 RPM's.

A stock Cummins is rated at 4200 RPM's for a 15 seconds in an over speed condition from the factory, but that's assuming valve springs that aren't already tired.

If you're running anything more than a 62mm charger or more than 45 psi of boost, you won't want to run past 3500 without heavier springs or you'll be floating some valves.

Like I said though, with a stock cam, you're kinda wasting your time anyways.

[68showngo]

Stock turbo. Thanks for the info. I've been wanting a cam, but want to wait until I can do springs, studs, and maybe some head work all at once and then be ready for more fuel and boost.

[DoghouseDiesel]

I normally tell guys to do the springs, studs and injectors at the same time. Otherwise you're just repeating labor.

With a cam....you want to do that ALL BY ITSELF.

It you start doing a cam, sticks, turbos, etc., all the same time, it makes it a PITA to weed out issues.

The only other thing I like to swap when we do cams are the pushrods, just because they need to come out anyways.

[68showngo]

I was thinking injectors and turbo later.. just some head work, springs, studs, and cam for now.. where you recommend starting and how much at a time? I plan on waiting with injectors until they go out, and turbo whenever I decide to I guess.

[comnrailpwr]

If they go out your engine could possibly go with them if the nozzles go aswell.

Spray & Pray

[FUBAR]

After modding the new tables, I'm able to command my fuel to 140mm3 up to 3200rpm. I didn't try to see how far past 3200rpm given the driving conditions I was in. I know someone said even though the logs was showing their commanded fuel was staying up, my seat of the pants meter was verifying the log. A dyno would come in very handy right about now...

[FUBAR]

Have you guys been seeing a set number where the pulsewidth has been cutting back to after 2800rpm?

[LReiff]

I've noticed that right around 2800rpm it hits 51.4 psi boost and CMD FUEL and Engine Load% drops off drastically. Command fuel instantly cuts to half and steadily drops as rpm climbs, Engine load does similar. Although this happens the engine continues to rev to the set rpm limiter but with greatly reduced power.

[MQ105]

I've noticed that right around 2800rpm it hits 51.4 psi boost and CMD FUEL and Engine Load% drops off drastically. Command fuel instantly cuts to half and steadily drops as rpm climbs, Engine load does similar. Although this happens the engine continues to rev to the set rpm limiter but with greatly reduced power.

Is this with the new tables and limits set properly?

[dansdieselp]

Is this with the new tables and limits set properly?

Yes

[FUBAR]

I was seeing duration getting cut back to 2400uS above 2800rpm consistently at the track tonite. Changed a few (butt load of) things to bump it up a little. She's definitely a different truck now with more fueling up in the Netherlands.

[dansdieselp]

I was seeing duration getting cut back to 2400uS above 2800rpm consistently at the track tonite. Changed a few (butt load of) things to bump it up a little. She's definitely a different truck now with more fueling up in the Netherlands.

Where you able to command anything higher than 2,400ms in the 3,000-3,500 range? The fact we have a table that is limiting commanded pw means we need to figure out what it is. There is more hidden power in them yet.

[DoghouseDiesel]

Correct me if I'm wrong, I never claimed to be a math wiz, but....

If you're turning 3500 RPM's, which gives you 58.33 RPS, which gives you 19,600 degs per sec, which gives you .196 degs per uS, even with 52 degrees BTDC and 25 degrees ATDC, that gives you a usable duration of 1411 uS.

Anything beyond that is going to hit the cutoff.

This was an 817 hp pull and at 3900 RPM's I was able to bring in 1920 uS of main duration with a command rate of 112. This spot on the main duration table correlates to 2012 uS, so it's within 5% of what I was asking for. This was gving me plenty of fuel to spare for a nitrous hit.

This was with a time of BTDC of 52* and ATDC of 22* for a total of 74* total usable duration.

http://i288.photobucket.com/albums/ll189/Cumminalong/Truck Pictures/DynoDataLog.jpg

Like I said, please correct me if I'm wrong in my math, but the fuel is there.

[Dmaxink]

What size injectors are you running Rich? That PW is smaller than stock and with stock injectors will not get a fella too far.. The problem many folks is that they are still asking for their desired pw@145mm3 and it is still getting cut. I'm assuming on your 817 pull the truck was at a much larger pulse when it made those numbers or you have large injectors. If a fella is asking for say a 3200 pulse @ x rpms that will give him x crank angle degrees. You can split this how you wish (dont forget about pressure) 40%btdc,50%btdc,60%btdc..ect however one would wish. The rollers (as you have stated) is the only way of seeing where timing is at its best... But if you have that 3200 duration the whole 3200 should be an efficient burn depending on how you have it timed in the chamber... just my .02 and trust me, im no math wizard either:grin:

[DoghouseDiesel]

My injectors are actually fairly small....they're only 37 LPH (160 hp).

The pulsewith I was asking for was 2012 and it was at 1920...within 5% of actual.

The problem is, you don't have 3200 uS of duration at those RPM's. 3200 uS of duration at those RPM's would be almost 150 degrees (very roughly) of crank angle.

If you look at the total time before and after TDC, you can see what your usable duration is.

If the injectors are small or large that has no impact on how much duration you have to work with. The only thing you can do there is increase / decrease total timing before and after or increase / decrease rail pressure.

Duration, unless you want less, is a pretty fixed number based on RPM and total timing and doesn't care what size the sticks are.

[FUBAR]

Where you able to command anything higher than 2,400ms in the 3,000-3,500 range? The fact we have a table that is limiting commanded pw means we need to figure out what it is. There is more hidden power in them yet.

The most I could get up to 3k RPM is 3000uS. After 3k RPM it cuts back to 2450uS. Initially I couldn't get past 2450uS AT ALL 2500-3000 rpm, but roughed in a few things to at least get it up to 3000uS. More fine tuning and refining to be done. And I'm sure you're all absolutely right about another hidden table.

[Dmaxink]

i was all excited because we kept a 2450 pulse all the way to 3800 rpms as we were commanding...but hopefully i will know by the end of today when the customer sends me back a log if the truck will keep a big pulse sustained off the race tune...im sure i will be in the same boat as everyone else, but wishing for the best... we will see...He said it is a constant pull until he hits the rev limit, but the butt-o-meter has been known to lie!

[FUBAR]

My injectors are actually fairly small....they're only 37 LPH (160 hp).

The pulsewith I was asking for was 2012 and it was at 1920...within 5% of actual.

The problem is, you don't have 3200 uS of duration at those RPM's. 3200 uS of duration at those RPM's would be almost 150 degrees (very roughly) of crank angle.

If you look at the total time before and after TDC, you can see what your usable duration is.

If the injectors are small or large that has no impact on how much duration you have to work with. The only thing you can do there is increase / decrease total timing before and after or increase / decrease rail pressure.

Duration, unless you want less, is a pretty fixed number based on RPM and total timing and doesn't care what size the sticks are.

So for my stock sticks, what you're saying is timing is more revelant to tuning it. My logic of thinking goes back to the basics: small sticks=longer pulse, more timing. Big sticks=short pulse, less timing. But from what I'm gathering from you Rich is regardless of sticks, you still have a set window to work with.

[DoghouseDiesel]

So for my stock sticks, what you're saying is timing is more revelant to tuning it. My logic of thinking goes back to the basics: small sticks=longer pulse, more timing. Big sticks=short pulse, less timing. But from what I'm gathering from you Rich is regardless of sticks, you still have a set window to work with.

Not necessarily.....

Yes, you are correct in that duration is a fixed number based on RPM and timing. The lower the RPM's and the more timing you have, the more usable duration you have to work with.

Now, do you NEED all that duration?....that's a matter of injector size. On small sticks, you may need all that duration to get the same power as a slightly larger injector. BUT, if the time you need isn't available, your only options are to either increase timing on the front and back ends OR increase the pressure (which I'm not a fan of).

The biggest key to power in these trucks isn't necesarily the duration...it's TIMING. Timing is power and the only way to see just how much you have is strapping it down. Doing it on the street or track can have BAD results, as it's a lot easier to damage the motor in conditions that aren't set.

You can sit at the computer and figure out all of your duration table before even going to the dyno. This will tell you the max you have to work with...UNTIL you start messing with timing. If you add 2* on the front and 1* on the back, you've given yourself more usable duration time. It's real simple, duration is time. If you don't have the time, you don't have the duration.

Rail pressure is easy...set it where you're comfortable with.

Strap it down and work on timing. Once you see no more gains from timing (or you see a decrease) back up 2 - 3* and you're good. From there, work on your duration and total time AFTER TDC.

What you'll see in the rollers is as you come up 2 - 3 degrees of timing per run, you'll see 10 - 35 hp jumps. Eventually, you'll stop gaining. That's your timing limit. Go farther than that and you'll get detonation.

Once you see your total timing, you can adjust the duration to give you your total usable time in uS.

Timing is key.

[dansdieselp]

The point I'm making is that we don't have full control over duration above 2,800. Doesn't matter if we can or can't use it all. I know there does come a point where more fuel stops adding power. We've had our test truck on the rollers and hp kept climbing until we hit the mystery table then it just leveled out. So there is more power to be had with a wider duration on stock sticks.

[DoghouseDiesel]

At what RPM and how much total timing is it leveling out at?

Actually, how much duration are you asking for at a given RPM?

Like I said, if the engine speed and timing don't allow for the duration you're calling for, those high duration numbers won't matter as you won't be able to get to them.

Doing the math will tell you if your outside the usable parameters.

[TwoStroke]

At what RPM and how much total timing is it leveling out at?

Actually, how much duration are you asking for at a given RPM?

Like I said, if the engine speed and timing don't allow for the duration you're calling for, those high duration numbers won't matter as you won't be able to get to them.

Doing the math will tell you if your outside the usable parameters.

How are you figuring the usable "window"?

[DoghouseDiesel]

All you're doing is breaking down the RPM's into degrees vs time and that gives you the total degrees per uS.

Once you have that, it's just multiplying that by your total timing to get the usable duration.

I have a tool that I use that all I do it plug in the RPM and the total timing and it gives you your MAX duration value.

[dansdieselp]

The dyno showed it peaked at 2,500 Leveled out til around 3000 then slowly tapered off. We've increased timing and duration to see if we would get a higher duration above 3k, but the logs were identical above 2,800 for duration.

[FUBAR]

Usable time to proper tuning makes sense to me. If you only got a certain size window to work with, it won't matter if you command twice as much time..i.e. How would you fit 3000uS in a 2000uS window? Ever heard of trying to fit a Cadillac in a Doghouse? (No pun intended)

[DoghouseDiesel]

The dyno showed it peaked at 2,500 Leveled out til around 3000 then slowly tapered off. We've increased timing and duration to see if we would get a higher duration above 3k, but the logs were identical above 2,800 for duration.

But, what are you asking for in duration and whats the total timing for that value?

I don't need the whole table, just give me 3200 RPM's at whatever pressure you're asking for.

[DoghouseDiesel]

Here's an example of what I do with the duration....pretty sure it looks nothing like what you have right now.

I completely change the fuel and pressure axis' so that they represent the actual values the engine operates within. With the stock tables, you have almost 25% of the tables that are TOTALLY unusable and aren't operated in at all.

I also change them so the daily driving ranges are much more accurate than the full throttle ranges.

And yes I did remove my values for this.....

In the daily driving conditions, I want smoke control...period. Narrow bands of adjustment, decent response, low smoke, okay power.

In the passing ranges, I'll deal with a haze, but I don't want it rollin' coal just to get around a semi. Here I want response, good power, light haze is acceptable.

In the WOT range, I make the adjustments farther apart as smoke control isn't really a concern. I want max response, full power, fairly dark smoke on throttle and light haze on bottle is okay.

http://i288.photobucket.com/albums/ll189/Cumminalong/Dohouse%20Diesel%20Pics/EFI%20Live%20Screen%20Shots/Slide1-11.jpg

http://i288.photobucket.com/albums/ll189/Cumminalong/Dohouse%20Diesel%20Pics/EFI%20Live%20Screen%20Shots/Slide2-11.jpg

[Dmaxink]

Nice explantion with the pic Rich, i would image it would help some guys out. I think Dan is saying regardless of timing no matter what uS he is demanding the truck is still limiting him past 2800 rpms. Rather timing is set at 0 or 54, the fueling should still be desired uS as timing plays no key on fuel quantity, but yet what time to start injecting it...Sorry if my statements come out funny, im not the best at explaining on the internet.

[DoghouseDiesel]

I certainly agree that there is something that is still unseen, but you can work around it.

Without seeing his tables, logs and dyno sheets though, it's a total guess.

I will say the fuel is there though. It took some tweaks, but it's there.

[DoghouseDiesel]

Just for giggles, if you're still having commanded fuel issues, check your pedal postion to desired fuel in your logs.

See if its actually commanding full fuel.

[comnrailpwr]

This is some great info. Keep up the good work and the updates coming

Spray & Pray

[dansdieselp]

Log shows 145mm3 all the way to 3600 where it falls off from there. One tune we tried sled pulling was 3000us at 180mpa at 47 degrees at 3200rpm. Log shows pulse was cut down to 2370 at 3100 rpm. The next tune we upped it 500us and 5 degrees and duration at 3100 was the exact same. Truck had more power with the added timing, but no extra fuel even though rail held 180mpa at 60%dc. I know what you're talking about that we only have such a small time to create an efficient burn, but even though smoke is black it is still getting burned and making power. In the duramax if I want to command lets say for example 3000us at 160mpa at 100mm3 I will get that number as long as rail keeps up. Cummins right now 2800 is the limit where it starts getting pulled regardless of how much timing and rail pressure there is. I think it's a for of engine protection. The mm3 falling off at 3,600 may be caused since a lot of the fuel limiting tables are only mapped up to 3,600.

[Dmaxink]

Sorry if I come off haste, but what I consider the fuel being there is if I'm desiring 3200uS of fuel@180mpa and it is letting me hold that 3200uS. The issue lies within I'm asking for it and its not.giving it to me, and its capable of it...the soft limiter is like a bully taking our candy and our hands are tied! We tried head butting..but our failure rate is substantial due to the bully being invisible. Lol (a little humor)..Rich, are you able to hold more than 2500uS at high rpms@145mm3? If so you have accomplished what we are after

[FUBAR]

Lol. Gotta love your analogies Kory.

[DoghouseDiesel]

Rich, are you able to hold more than 2500uS at high rpms@145mm3? If so you have accomplished what we are after

Honestly, there are only 2 spots on my duration map that are USABLE I'm asking for 2500+.

Let me go look at the logs real quick.

[DoghouseDiesel]

Okay, lets see.....

1900 RPM, 2949 Main Dur, 138 Commanded
2000 RPM, 2987 Main Dur, 151 Commanded
2100 RPM, 2934 Main Dur, 153 Commanded
2200 RPM, 2922 Main Dur, 153 Commanded
2400 RPM, 2912 Main Dur, 154 Commanded
2500 RPM, 2912 Main Dur, 156 Commanded
2600 RPM, 2790 Main Dur, 156 Commanded
2700 RPM, 2704 Main Dur, 155 Commanded
2900 RPM, 2581 Main Dur, 153 Commanded
3000 RPM, 2501 Main Dur, 150 Commanded
3100 RPM, 2400 Main Dur, 145 Commanded
3300 RPM, 2344 Main Dur, 142 Commanded
3400 RPM, 2230 Main Dur, 137 Commanded
3500 RPM, 2117 Main Dur, 135 Commanded
3600 RPM, 2071 Main Dur, 132 Commanded
3700 RPM, 2027 Main Dur, 130 Commanded
3800 RPM, 2012 Main Dur, 128 Commanded
3900 RPM, 2004 Main Dur, 126 Commanded
END OF RUN

Looking at my tables, even where the duration drops, it's within 5% of what I'm asking for. The lowest I ask for in those runs is 2012 on the main duration and those also correspond with the drop off that I have on the high side of my RP map. Aftter 3600, I start bringing the RP down.

[Dmaxink]

Did you set up the tune to drop duration and mm3 with the limiter tables..or is it in fact doing as everyone else's and still pulling duration and mm3 as ours?

Fubar- in tuning it gets so wild at times ya just have to throw some humor in sometimes! Haha if anyone meets me at world finals you will see I'm all bout fast trucks and good times!

EDIT: Rich, just seen you said you bring frp down which would mean the drop in duration..so I'm assuming its giving you the duration your commanding or is it dropping from the ghost limiter?

[DoghouseDiesel]

This is 3 pulls before the high pull. This was approx 730 hp....

2000 RPM, 2220 Main Dur, 136 Commanded
2100, 2231, 141
2200, 2329, 150
2400, 2353, 155
2500, 2340, 155
2700, 2362, 156
2800, 2329, 153
2900, 2283, 151
3000, 2285, 148
3100, 2261, 147
3200, 2224, 144
3300, 2209, 139
3500, 2113, 131
3600, 2071, 129
3700, 2008, 125
3800, 2004, 124
END OF RUN

[DoghouseDiesel]

EDIT: Rich, just seen you said you bring frp down which would mean the drop in duration..so I'm assuming its giving you the duration your commanding or is it dropping from the ghost limiter?

I peak my RP at 3600 and then taper it off to prevent spikes.

I normally don't shift any higher than 3600 on a run, so that's where I cut the pressure down.

Yes, the drops in mm3 are corresponding to the RP drop.

[LReiff]

@ 1rpm there is 6 degrees of rotation per second (dps)

Therefore the equation is dps@1rpm X desired rpm = dps at desired rpm

One microsecond (µs) looks like this> .000001

6dps X 3000rpm = 18000dps

18000dps X .000001 = .018 degrees per µs (dpµs)

I have a data log of 2422µs main and 223µs pilot and 45 degrees Injection Timing @ 3000rpm

2422 + 223 = 2645µs total

.018dpµs X 2645µs = 47.61 degrees, which is within approx. 5% of 45 degrees

Is 5% variation acceptable? Am I just running circles? This shows logged timing to be correct?

Add a 300µs post shot in the mix and you'd end up with 53 degrees injection timing?

How does C7003 relate to C7001?

[comnrailpwr]

Thats very interesting...

Spray & Pray

[Dmaxink]

the equation will give us "x" amount of Crank Angle Degrees...how we so choose to split the CAD btdc/atdc would make these tables make a little sense. If we have say 50 crank angle degrees, and slit it by 50% btdc and 50% atdc, that would give us 25* (aka in the cummins table '45*' given the 20* offset)

[2007 5.9]

@ 1rpm there is 6 degrees of rotation per second (dps)

Therefore the equation is dps@1rpm X desired rpm = dps at desired rpm

One microsecond (µs) looks like this> .000001

6dps X 3000rpm = 18000dps

18000dps X .000001 = .018 degrees per µs (dpµs)

I have a data log of 2422µs main and 223µs pilot and 45 degrees Injection Timing @ 3000rpm

2422 + 223 = 2645µs total

.018dpµs X 2645µs = 47.61 degrees, which is within approx. 5% of 45 degrees

Is 5% variation acceptable? Am I just running circles? This shows logged timing to be correct?

Add a 300µs post shot in the mix and you'd end up with 53 degrees injection timing?

How does C7003 relate to C7001?

If i do mine...2500uS at 3000...I get 45* which is 12% more than I am commanding....

[FUBAR]

Lee,

I can tell you this is how I setup my timing and duration table. I found that to be a very good rule of thumb save for it was a little much (timing rattle.)

When I asked for 45 deg.....scratch that, 25 deg actual (man I hope they straighten this Bias thing out soon) BTDC, I was getting a faint rattle. Backed it down to 22 deg BTDC, balanced it out a little heavier ATDC a few more deg (22* BTDC, 27* ATDC) gives me a 45%BTDC, 55%ATDC. I'm able to attain 3,000uS a 3,000RPM and egt's are in check as well as smoke (haze.) Now if you do the math, I should have to have 54 deg of total timing to pull that off, but I'm only using 49 deg total timing in the tune for a total of 9% difference less than theory. Oh, and 3200uS is what I'm commanding as well. I just need to work the rest of the area of tables now.

-Andrew

[2007 5.9]

One question I have is...with you running more % of total timing ATDC, is it worth any power?? The game as I have always played it, is more timing BTDC to a point yields the best power...

Essentially if I am understanding you correctly...your running 22*BTDC and 27*ATDC at 3000rpm's...with no pilot event??

So in essence your running a "Split Main Event"???

~Les

[FUBAR]

Well, yes and no. I was running a just a Main shot but then I started running Pilot again to eliminate any variables. My reasoning is, tune Main, and Pilot's just there to help get it to work. Another words, I think Pilot has a minuscule effect on the tuning side of things, that I focus just on tuning main. After all, pilot is dependent on what Main does. If I thought the other way, I would think one would be able to fully control when pilot starts independent of main. Because if you look at the timing numbers pilot is before main, they're just plain crazy even with 20* bias taken out.

I AM very much interested on what you and other people think about this as well.

-Andrew

[LReiff]

Andrew, is it possible that C7003 is the 20 degree bias? I have not changed it so I have no clue what it does.

[MQ105]

How does C7003 relate to C7001?

C7003 is the earliest all injection events can finish, C7001 limits the latest the main event can finish.

[68showngo]

Looks like my fueling issues are fixed! Saw up to 144 mm3 at 3000 Rons I think it was and never saw 140 or above anywhere before.. all I did was mess with the limiters on the latest release.

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[GMPX]

That new parameter didn't directly affect the commanded mm3, it was causing issues on the final pulse time.
Eg, you might have seen 144mm3 being commanded, you may have been calling for 3,000uS pulse time, but when logging you were only getting a 1,900uS pulse. The new parameter ensured the desired high pulse times didn't get scaled back.

[68showngo]

Ok I wasn't even sure but either way it works.. not sure if I messed something up or forgot a few things about logging but had some issues with some of the stuff.. hopefully rob will get me dialed in a bit better soon! :)

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