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Thread: Post injection delete questions

  1. #1

    Post injection delete questions

    Those of you who have deleted only the 3rd event, what sort of gains did you see? Cleaner oil? What did you adjust in the main timing and duration after zeroing out the post event? Any other thoughts?

    Thanks
    2004.5 Cummins.
    Borgwarner 13009097047 s300sxe 63-73 compressor 63/80 super core turbine housing 80mm .83 A/R Twin Scroll Housing,
    50HP BMS/Exergy Injectors
    BD T4 manifold,
    BD CAI,
    5" turbo back exhaust,
    turbosmart ext wastegate,
    BD lift pump with 2 mic filter and h2o separator,
    banks intercooler, Banks intake horn,
    slightly built tranny.......

  2. #2
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    No difference really. Might see a slight, very slight increase in main injected quantity commanded by the ecm. Eliminating post injection is so unnoticeable that if you were drive a truck with it then without it and not be told which one had the post event removed, you wouldn?t even know which one was which. One of the thoughts people remove the post event is injector life, 1 less pulse per cycle to reduce needle wear on the injector. I don?t see any real need to adjust main timing just for eliminating post event. Post event is there for emissions and has probably very little influence on the combustion of the main injection event unlike the pilot event. Improperly tuned post event can result in poor fuel economy. On a stock tune stock truck the mpg difference having a post event and no post event is negligible.

  3. #3
    Quote Originally Posted by Jim P View Post
    No difference really. Might see a slight, very slight increase in main injected quantity commanded by the ecm. Eliminating post injection is so unnoticeable that if you were drive a truck with it then without it and not be told which one had the post event removed, you wouldn?t even know which one was which. One of the thoughts people remove the post event is injector life, 1 less pulse per cycle to reduce needle wear on the injector. I don?t see any real need to adjust main timing just for eliminating post event. Post event is there for emissions and has probably very little influence on the combustion of the main injection event unlike the pilot event. Improperly tuned post event can result in poor fuel economy. On a stock tune stock truck the mpg difference having a post event and no post event is negligible.
    Great explanation! Thank you!
    2004.5 Cummins.
    Borgwarner 13009097047 s300sxe 63-73 compressor 63/80 super core turbine housing 80mm .83 A/R Twin Scroll Housing,
    50HP BMS/Exergy Injectors
    BD T4 manifold,
    BD CAI,
    5" turbo back exhaust,
    turbosmart ext wastegate,
    BD lift pump with 2 mic filter and h2o separator,
    banks intercooler, Banks intake horn,
    slightly built tranny.......

  4. #4
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    Quote Originally Posted by Jim P View Post
    Improperly tuned post event can result in poor fuel economy. On a stock tune stock truck the mpg difference having a post event and no post event is negligible.
    How do you properly tune a non post tune?
    And how could it result in bad economy. I did hear it could effect spool.

  5. #5
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    You misread. If you are running post event, an improperly tuned post event can have large effects on fuel economy and reduce economy

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    Having the post too close to the main or having it too large is going to drive turbo speed up. When running in a state where you are wanting fuel economy, cruising, you want to get your turbo speed down. You can use post to ?extend? the main injection to help with spooling up large single turbos. The post, the way it is intended to be used, for emissions is to have just enough of it injected at the right time when there is still enough heat to ignite it to burn up any remaining fuel, soot, etc from the main event. Wish I could find a really good research article on the effects of pilot, main and post to post up a link to

  7. #7
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    Good explanation. I am currently running no post and havent really noticed any mpg gains but I am also messing with other stuff like no pilot and I feel like I might be loosing economy by not tuning that right

  8. #8
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    You won?t see any gains in the mpg department by running zero post. Try this if messing with single injection events.

    Take a data log at completely stock tuning. Log main injection quantity. Remove post and log again. Any increase observed in main quantity try raising entire pulsewidth table a few microseconds at a time till main quantity and everything else is back down to where it was before removing the post event. This is all assuming removing the post event causes a noticeable change, increase in main quantity commanded.

    Now start turning down pilot quantity and timing a little bit at a time, main timing will need a small bump up every little bit as well. As you take away pilot, log and observe main quantity and as it comes up from after any main duration adjustments to have the main quantity back to where it would be stock, add a few more microseconds of duration to bring main quantity back down to where it would otherwise normally be.

    Observe your pilot timing initially. While end result your main timing won?t need to be that high on a CR 5.9 it should give you an idea of how that main timing needs to be increased because as pilot is being removed you are removing that ?pre-heat? flame front that allows for the closer to TDC main injection event, you are increasing ignition delay when removing pilot.

    Keep going through the cycle till you get a smooth running engine on single event.

    See how it goes for you anyways.

  9. #9
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    Quote Originally Posted by Jim P View Post
    You won?t see any gains in the mpg department by running zero post. Try this if messing with single injection events.

    Take a data log at completely stock tuning. Log main injection quantity. Remove post and log again. Any increase observed in main quantity try raising entire pulsewidth table a few microseconds at a time till main quantity and everything else is back down to where it was before removing the post event. This is all assuming removing the post event causes a noticeable change, increase in main quantity commanded.

    Now start turning down pilot quantity and timing a little bit at a time, main timing will need a small bump up every little bit as well. As you take away pilot, log and observe main quantity and as it comes up from after any main duration adjustments to have the main quantity back to where it would be stock, add a few more microseconds of duration to bring main quantity back down to where it would otherwise normally be.

    Observe your pilot timing initially. While end result your main timing won?t need to be that high on a CR 5.9 it should give you an idea of how that main timing needs to be increased because as pilot is being removed you are removing that ?pre-heat? flame front that allows for the closer to TDC main injection event, you are increasing ignition delay when removing pilot.

    Keep going through the cycle till you get a smooth running engine on single event.

    See how it goes for you anyways.
    When I increase my duration do I add it to the whole table, like say a 10% increase to every box? And where is quantity commanded? Isnt that my pedal map?

  10. #10
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    poor choice of words on my part, what I mean by quantity commanded is actual main quantity injected. You can apply to whole table or just to specific areas. Specific areas you will be covering a limited area, the whole map you?ll be covering it all but some areas may need a touch of duration taken away instead of increased. Don?t take large amounts off or on at a time like 10%, you?ll be chasing tails with that amount. For example on my 2012 before removing post it was running around 10-11mm3 main Injection quantity at idle, remove post and its up at 13-14mm3 main injection quantity, like 3 1% bump ups on the duration table brought it back to 10-11mm3 main injection quantity and seems to be working well for me. Granted a 4th gen 6.7 works way differently than a 3rd gen 5.9. Now if I did 10% that would have been way too much and that?s where tail chasing can start happening.

    Personally I?ve never bothered to play around with single injection tunes but the above post is how I would approach it.

    Pedal map is user desired fuel. Doesn?t mean if you put 15mm3 at 25% throttle and 1600 rpm that you get just that. It?s like a starting point to engine running through algorithms to determine final amount of fueling.

  11. #11
    I was hoping to keep this to a post/ 3rd injection event thread only. There are plenty of single injection threads out there, however not a lot of explanation on what needs to be changed to run a post delete. There are also not a lot of threads out there with any real data regarding the 3rd event removal. Anyone else have good or bad results from this? I still wonder if the cleaning up the oil myth is true. Not much info on that.
    2004.5 Cummins.
    Borgwarner 13009097047 s300sxe 63-73 compressor 63/80 super core turbine housing 80mm .83 A/R Twin Scroll Housing,
    50HP BMS/Exergy Injectors
    BD T4 manifold,
    BD CAI,
    5" turbo back exhaust,
    turbosmart ext wastegate,
    BD lift pump with 2 mic filter and h2o separator,
    banks intercooler, Banks intake horn,
    slightly built tranny.......

  12. #12
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    It?s just that, a myth. Where people have noticed oil staying cleaner longer is on a single event top. Results between having post event and not having post is so little that like I said, if you weren?t told, you wouldn?t notice a difference at all and if told, you wouldn?t notice a difference at all. You can take a log of both and compare and may see some differences but those differences are so so tiny it takes a data log to even notice it.

  13. #13
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    One thing to note with oil, just because it?s black doesn?t mean it?s bad

  14. #14
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    I got my no post down with 7% increase in main pw and it was actually really cool to tune lol. Now I just want to try and do the same for pilot and try and get a true single injection tune just for giggles. I think I will start by reducing pilot then run it and add main pw and a little timing to go with it until I get no pilot. Only thing is that I do not know how to properly do timing, can I just use a timing calculator and then just work from there?

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    There is no magic number or percentage with timing. There?s rules of thumbs for percentage on the upper end for street tunes(non-dyno tuned). Start with 0.5* increase at time, give more if needed or less. Listen to videos of 12 valves then listen to the sound of your engine

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    Even better to listen to how a VP truck sounds as technically that?s what you are working towards. A 12 valve has static timing and dynamic injection pressures. A VP has dynamic timing and pressures just no pilot or post event. Maybe take a look at a stock VP tune as well.

  17. #17
    Quote Originally Posted by Jim P View Post
    Even better to listen to how a VP truck sounds as technically that?s what you are working towards. A 12 valve has static timing and dynamic injection pressures. A VP has dynamic timing and pressures just no pilot or post event. Maybe take a look at a stock VP tune as well.
    I don't think a stock vp tune will help at all since the common rail is a whole different animal. Maybe im wrong though.
    2004.5 Cummins.
    Borgwarner 13009097047 s300sxe 63-73 compressor 63/80 super core turbine housing 80mm .83 A/R Twin Scroll Housing,
    50HP BMS/Exergy Injectors
    BD T4 manifold,
    BD CAI,
    5" turbo back exhaust,
    turbosmart ext wastegate,
    BD lift pump with 2 mic filter and h2o separator,
    banks intercooler, Banks intake horn,
    slightly built tranny.......

  18. #18
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    Pistons are different, injectors are different, Injection pump is different, not mistaken turbo is different as well but will give an idea of what a single injection tune looks like on the 24 valve engine. Will it be exactly the same for a CR engine? No, but there will be similarities to degrees. Timing will need to be increased kinda like how you see a VP truck.

  19. #19
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    But how will I know if I have two much timing or not enough

  20. #20
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    Too much timing will be quite rattley. No pilot injection the combustion event will be louder regardless. Not really sure how to describe the sound other than if it sounds like you have rod knock you probably got too much timing.