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Thread: timing or fuel

  1. #1

    timing or fuel

    Im looking to make my truck a little more responsive in-between shifts on my six speed. I have adjusted my governors and gotten my limiters out of the way. adjusted my wastegate duty cycle and added timing in the upper mm3 area. My question is do you recommend me adjusting the factory timing in my low mm3 and boost areas or add more pulse width to achieve my goal? What would be a good starting point?
    im leaning towards messing with my pulse width because the worst case scenario its just smokey? versus timing is still a mystery to me

  2. #2
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    Quote Originally Posted by bradshaw106 View Post
    Im looking to make my truck a little more responsive in-between shifts on my six speed. I have adjusted my governors and gotten my limiters out of the way. adjusted my wastegate duty cycle and added timing in the upper mm3 area. My question is do you recommend me adjusting the factory timing in my low mm3 and boost areas or add more pulse width to achieve my goal? What would be a good starting point?
    im leaning towards messing with my pulse width because the worst case scenario its just smokey? versus timing is still a mystery to me
    I have noticed getting timing up and mostly positive across the map has helped my truck a lot.. also for stock injectors I only mess with the pulsewidth in bottom right of the table (high mm3/high rail pressure)

  3. #3
    Quote Originally Posted by bradshaw106 View Post
    Im looking to make my truck a little more responsive in-between shifts on my six speed. I have adjusted my governors and gotten my limiters out of the way. adjusted my wastegate duty cycle and added timing in the upper mm3 area. My question is do you recommend me adjusting the factory timing in my low mm3 and boost areas or add more pulse width to achieve my goal? What would be a good starting point?
    im leaning towards messing with my pulse width because the worst case scenario its just smokey? versus timing is still a mystery to me

    What does the log say during the shift?

    Set the rail pressure how you want it, then reset the timing to match. Once thats done then go evaluate performance during shifts. If you want throttle response... light weight wheels, aluminum driveshaft and light weight pulleys on the motor. And if your really motivated, electric water pump. I have all this and have dialed fuel back significantly in an effort to gain the most mpg for my daily driver and throttle response is still "fun". (21~23 mpg on winter fuel, 2005 ram 2500 4wd, stock height with 33" tires and late G56 trans)

    leave duration alone...
    Last edited by steve05ram360; 01-24-2020 at 11:48 AM.

  4. #4
    Advanced Tuner JaegerWrenching's Avatar
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    Quote Originally Posted by steve05ram360 View Post
    What does the log say during the shift?

    Set the rail pressure how you want it, then reset the timing to match. Once thats done then go evaluate performance during shifts. If you want throttle response... light weight wheels, aluminum driveshaft and light weight pulleys on the motor. And if your really motivated, electric water pump. I have all this and have dialed fuel back significantly in an effort to gain the most mpg for my daily driver and throttle response is still "fun". (21~23 mpg on winter fuel, 2005 ram 2500 4wd, stock height with 33" tires and late G56 trans)

    leave duration alone...
    Are you using a timing calculator? Is that what you mean by reset the timing after a fuel pressure change?

  5. #5
    Tuner MAIDENCR's Avatar
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    forget timing calculator....when you add pressure....injector open faster and more fuel is injected so timing need to be adjusted.....took me 2 summer to get the dialed in...and will need to do it again since installed really big injectors

    look at my video to see the responsiveness https://youtu.be/N_2Jx-mMTP8

    Quote Originally Posted by JaegerWrenching View Post
    Are you using a timing calculator? Is that what you mean by reset the timing after a fuel pressure change?
    03 cummins,100hp nozzle,dual cp3,s467.7/83 1.00
    Nv5600 with valair triple disc clutch

  6. #6
    Advanced Tuner JaegerWrenching's Avatar
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    Quote Originally Posted by MAIDENCR View Post
    forget timing calculator....when you add pressure....injector open faster and more fuel is injected so timing need to be adjusted.....took me 2 summer to get the dialed in...and will need to do it again since installed really big injectors

    look at my video to see the responsiveness https://youtu.be/N_2Jx-mMTP8
    I'm simply asking a question, i'm curious what he is doing to "reset" his timing. I never said to use a timing calculator now did I? Your statement about getting more fuel in because of higher pressure alone is Only true if you are commanding more fuel while increasing fuel pressure simultaneously, or if your injector is too small and you're maxed out spraying as much as you can in your set window of allowed injection. The ironic part to all this is, this is the one time i'd actually see the use of a calculator be plausible to keep my current split window as close to previous after a fuel pressure change. But you'd have to know your current split is optimal to even be able to want to match it after a pressure change.

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    Tuner MAIDENCR's Avatar
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    You asked if he use the calculator...i said to not use it...my split i do it with some math equation ...you will inject more fuel if you raise pressure for a given mm3....

  8. #8
    Quote Originally Posted by MAIDENCR View Post
    You asked if he use the calculator...i said to not use it...my split i do it with some math equation ...you will inject more fuel if you raise pressure for a given mm3....
    I have been trying to find the math formula online, but haven't had much luck. Can you post it please?
    Their is a comment on this forum where I saw it but cant find it again

  9. #9
    Tuner MAIDENCR's Avatar
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    (RPMx360)/60000=crank rotation for 1ms
    Crank rotationXduration=total degree of injection
    Then you multiply your total degre by % you want before tdc and it give your timing

    Exemple:
    (4000rpmX360)/60000=21?
    21?x 2.5ms(2500is)=52.5?
    52.5?x .65(65%)=34? before tdc

  10. #10
    Advanced Tuner Jim P's Avatar
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    Exactly what timing calculators are set up to do...

    Truly tells you nothing about timing being correct or not.
    Last edited by Jim P; 01-25-2020 at 08:17 AM.

  11. #11
    Advanced Tuner JaegerWrenching's Avatar
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    Quote Originally Posted by Jim P View Post
    Exactly what timing calculators are set up to do...

    Truly tells you nothing about timing being correct or not.
    Exactly, it gives you 0 information on flame speed or pressure rise rate. But it's all mathy and stuff so it must work.

  12. #12
    Advanced Tuner Jim P's Avatar
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    Lol I second that.

  13. #13
    Advanced Tuner Jim P's Avatar
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    To the original question, if running stock truck, majority of the duration table you can leave alone. Messing with the duration table really depends on your ultimate goals. Sure you could tweak the table throughout its entirety to match it to your injectors actual flow rate, can send your injectors in to be mapped out but with stock injectors it?s pretty much fine as is. If you got high mileage injectors, about a 3% increase in duration across the board can ?restore? responsiveness and power. Can increase duration in the upper mm3 and rail pressure range for higher torque output, 70mm3 and up and 120MPa and up, this can increase responsiveness. You?ll have to play around with rail pressure, timing, etc in the spots you want better response in to find what your truck likes and what works well for you. Getting these truck to put out 20-23mpg every day of the year with custom tuning isn?t overly daunting or trivial and doesn?t require light weight pulleys, electric fans, wheel well ducts or any other gizmo when working with custom tuning, whether stock engine or a 700hp twin turbo engine or stock tires or 33? tires which are barely larger than stock. All it takes is time getting your truck dialed in through custom tuning. Most add-ons that claim +1-3mpg are nothing but marketing hype, even going as far as installing manual locking hubs to keep the front drivetrain from rotating when not being used. I never seen any discernible difference it ECM output in data logs showing that free spin hub kits put less load on the engine to reduce fuel output. They have high upfront cost for cheaper bearing replacement down the road is all. Electric fans and such just move load to the alternator which is pulley driven by the engine, more electrical load puts more work load on the engine to create the current needed to drive electrical components. The stock fan will flow more air when needed compared to electric fan and it is duty cycle driven, using an electric pulse to control the engagement of the fan from basically free spin to full locked, kind of like an electronically controlled torque converter in an automatic transmission. Cold air intakes really do nothing for you below 550hp or so, stock air filter flows more than enough air to push a stock turbo to its extreme limits. Ultimately just make small changes in your tuning till you find the feel you like and get the results you like. Your duration, rail pressure and timing are all going to play an effect in achieving your end game.

  14. #14
    Quote Originally Posted by JaegerWrenching View Post
    Are you using a timing calculator? Is that what you mean by reset the timing after a fuel pressure change?
    Nope... no timing calculator. Using the stock duration table, the goal for me is to find the point at which there is a slight haze of smoke out the back.

    My process overall
    1) set the rail pressure (RP) on the transient RP table, onces set, copy over to the High altitude table

    2) set the timing (T) for the updated RP table at a fixed rpm with a wider load range
    * this is a 12 mi route down the hiway going over hills at a set speed using cruise (CC)
    * adjust timing as need to find the haze @ all load values (requires an eye on the exhaust)

    3) Fine tune it by looking at the Calc Load (CL) values across the steady state of the data log run.
    * look at adjusting timing one way or the other and repeat data log run. lowest CL values wins (this is repeatable)

    4) drop the duration by 1% increments until the haze is gone.
    * this requires the duration table to be set back to the stock values each time 1% decrement, meaning the 2% drop comes from the stock setting, 3% drop comes from stock setting


    So what does that do for me... based on my research the peak pressure is put somewhere in the 12~16* ATDC range giving me the best MPG (my goal).

    After that first dial in session... ANY follow up changes requires a base run the day of the changes. I've found that the variation from day to day is enough to throw things off so a base run is a must. "how do you know where to go unless you know where you've been (or at)"


    This is my process, allows me to get what I want out of it (currently 21~23 mpg year round, yes in the winter and on winter fuel, receipts to back it up). Note that there is a significant amount of rotating mass reduced from my truck... driveshaft, wheels, pulleys and an electric water pump. I leverage it all.

    A final note... when I go to tweek a tune in the rail pressure area... when I drop 1 mm3, I increase timing in the corresponding cell by 0.25* to keep things close. This is with rail pressure all the way down in the 11~13k psi range, higher rail pressures may take more to keep it close to where it needs to be.

    Hope this helps...

    btw, dont forget the timing correction tables, if they are not set right or close to right you can be chasing your tail...

  15. #15
    Quote Originally Posted by Jim P View Post
    To the original question, if running stock truck, majority of the duration table you can leave alone. Messing with the duration table really depends on your ultimate goals. Sure you could tweak the table throughout its entirety to match it to your injectors actual flow rate, can send your injectors in to be mapped out but with stock injectors it?s pretty much fine as is. If you got high mileage injectors, about a 3% increase in duration across the board can ?restore? responsiveness and power.

    Can increase duration in the upper mm3 and rail pressure range for higher torque output, 70mm3 and up and 120MPa and up, this can increase responsiveness. You?ll have to play around with rail pressure, timing, etc in the spots you want better response in to find what your truck likes and what works well for you.

    Getting these truck to put out 20-23mpg every day of the year with custom tuning isn?t overly daunting or trivial and doesn?t require light weight pulleys, electric fans, wheel well ducts or any other gizmo when working with custom tuning, whether stock engine or a 700hp twin turbo engine or stock tires or 33? tires which are barely larger than stock. All it takes is time getting your truck dialed in through custom tuning.

    Most add-ons that claim +1-3mpg are nothing but marketing hype, even going as far as installing manual locking hubs to keep the front drivetrain from rotating when not being used. I never seen any discernible difference it ECM output in data logs showing that free spin hub kits put less load on the engine to reduce fuel output. They have high upfront cost for cheaper bearing replacement down the road is all.

    Electric fans and such just move load to the alternator which is pulley driven by the engine, more electrical load puts more work load on the engine to create the current needed to drive electrical components. The stock fan will flow more air when needed compared to electric fan and it is duty cycle driven, using an electric pulse to control the engagement of the fan from basically free spin to full locked, kind of like an electronically controlled torque converter in an automatic transmission.

    Cold air intakes really do nothing for you below 550hp or so, stock air filter flows more than enough air to push a stock turbo to its extreme limits. Ultimately just make small changes in your tuning till you find the feel you like and get the results you like. Your duration, rail pressure and timing are all going to play an effect in achieving your end game.
    Had to break this up to be able to read it...

    Duration table, I would think you should be able to slope the table differently so there is less on the lower MM3 demand (higher duration) & more on the upper MM3 (lower duration). I thought about doing this but I dont need high fueling so why bother? If my needs change, so will the tune. You change the tune on the bottom end, not to the top end (MM3 demand) to improve responsiveness. I can advance my timing on the bottom end right out of the ideal sweet spot and loose boost. When I reach that point I know I've gone too far and pull it back, ideally until I find that slight haze I spoke of.

    20-23 mpg comments, can you get the guys who you know who have done it in here so they can chat about what they have done? RE: my truck, sure none of that (fans, pulleys, drive shaft etc) is needed however getting into the 20's year round before making those changes has never been a feat my truck has possessed ... in all the area's I've worked and daily driven my truck in. E-fans are definitely the way to go, towing heavy, light or not at all. The only time the fans come on is when they are needed, then the load shifts to the ALT and may not even match what the mechanical fan draws from the motor. The mechanical fan will always draw air, engaged by the ECU or not... had I had my anemometer back when I found out, I would have take measurements and posted them up. All the load that is removed from the engine affects performance, driveshaft, pulleys, fan. Its up to the programmer to decide to leverage it or not. The biggest change noted each time the load was taken off the motor was throttle response. If timing is not set right, boost can be lost. How do I know??? I lost boost with the driveshaft install. Boost started @ ~1100 rpms before the install, then was something like 1300 rpms. This is where I discovered the slope of the timing can affect motor output... Fixed it and learned from it. Then had boost starting as low as 900 rpms. Yes it all matters an its up to the programmer to take advantage of it.

    Cold air intakes, agreed, only hurt performance unless up in the higher rpm range. When I did one I lost spool rpms and never caught on until I went back to the stock intake years later. Then the eyes were open to the bottom end throttle response. A few years after that I switched to the MT from the 48RE and then had the opportunity to see what does what for throttle response (AL parts). It was 2~3 years later that that opened my eyes again, and fully leveraged all of that.



    Anyways, if you can get those in here who have had great success getting 20+ mpg year round, I'd like to chat with them.

    Anyone else reading this who wants to see the journey I took, its all on cummins forum, search my screen name & you'll find it, its all there, good & bad.

    Edit: BTW, there is nothing flat about the Seattle area (where I live) so there is always a hill your either going up or down... Longest flat stretch that I have on my commute is 2~3 miles. 31 miles one way...
    Last edited by steve05ram360; 01-26-2020 at 08:52 PM.

  16. #16
    Advanced Tuner Jim P's Avatar
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    Back when custom tuning first came out for the 3rd gens, 2012 I believe it was, only thing available was crude UDC tuning on the smarty handhelds. Main timing, duration, rail pressure, wastegate (which was useless for me as I didn?t run a stock turbo) and some nonsensical table for torque management that no one knew what it actually adjusted as about all you had available to tune, no correction factor tables and all the other stuff available now. It was crude. Ran a pretty average 21mpg everyday of the year on the transmission eating 2005 6 speed manual I had at the time, passing through the Rockies or whatever, it was pretty consistent on mpg above 20.

  17. #17
    I did UDC back then as well... was able to get into the 20-21 range during the warmer months only. Managed 20.3x during a "cold weather" effort I did where I learned 100*f + IATs & 200*f CTs were king. That was out there in MN during a mild winter. MN is mostly flat, nothing here is flat. Had a bet with a co-worker in 2018 that I could not get 5 tanks to average 23.0+ mpg. Learned a lot during that bet as well. Anyways, sounds like I still have some to learn if UDC can get you 20+ year round...

  18. #18
    Advanced Tuner Jim P's Avatar
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    I find the 5.9?s easier to get a steady 20-23mpg compared to the 6.7?s like my 2012. I have a single event tune written for it that gets steady in that mileage range but when mixing in pilot and post it?s more challenging.

  19. #19
    Interesting, I know a tuner who has an easier time getting higher #'s out of his 6.7 & struggles with clean 5.9 mpg tunes. he also pushes a single event tune. Maybe I need to go revisit it (single event tune) knowing what I know now. Last time I had one it was a mixed tune, Pilot was enabled up to 800 rpms then single event after that. The driver to send me back to the 3 event tune was being stuck in an airport parking lot in 29*f temps and the motor being very unhappy beyond the 800 rpm mark. Had to sit & wait for it to build enough heat in the motor to roll out, and even then I was limited to the back roads until more heat was into the motor.

    As for post, its use is limited in the current tune and is only in a select # of cells in the 1200-1600 range, basically to help spool. I probably dont even need it now with the way the throttle response has changed with the rotational mass reduction.

    I will go back and revisit the last single event tune I had and see how far off things are compared to what I have now (compensation wise), maybe its time to dive back into it.
    Last edited by steve05ram360; 01-27-2020 at 08:52 AM.

  20. #20
    I also have a much easier time getting clean good milage tunes out of a 6.7. The 5.9's just aren't quite as easy to get it out of. The 3rd gen 6.7's especially I've been able to be in the 21-22 pretty consistently.