That's fine and dandy as long as you don't modify the injection pulse table. Even then, you have to take any of those calculations with a grain of salt.
Mileage Timing??
- Thread starter wdino73
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From what I have seen, the factory injection pulse width tables aren't really that accurate to begin with. It will get you in the ballpark, but that is it. That is why the LB7's had a "DIC Fuel Used Adjustment" table. Mine had as much as a 23% adjustment stock, and over 85% after modifying the PW. This is to make the dash accurate when using the reported mm3 values.
IMO the LBZ and newer have pretty close PW tables stock, but even then they are not perfect.
how does one go about correcting and optimizing the tables? I've been playing with some past logs and creating maps in efilive scan software.. it makes some pretty charts but nothing that I know how to use just yet in actually "tuning" a diesel. I come from the gas world and knoiw all about correcting MAF and VE tables. For instance.. how is it determined the optimal injection timing for a given RPM vs fuel delivery? Or now with VVT diesels, the optimum vane position? I know both probably have that "sweet" spot. If I've missed some good reads on the subject by all means point me to them!
Mike what do you mean by 70/30 timing map??
70% injection event before TDC and 30% after if I'm not mistaken.
Why is it we cant have the cake and the icing? See no reason we cant merge many tunes into one super tune. For instance.. the throttle position map should be setup more like a J-curve.. so daily driving wont take a toll on economy but mash on the throttle more and the engine will definately wake up. Second, timing and boost maps can be altered where only unloaded light throttle driving has gobs of timing and off these areas can be tuned for aditional power. I've seen the timing calc excel spreadsheet but I see no reason to apply a 70/30 or 50/50 or any other combination to the entire map
lets go from another angle.. without the feedback from a cylinder pressure transducer or even a dyno for most of us, what data can be used to get acceptable realtime engine effeciency? maybe load % at a steady speed? what i'd like to do to speed up the tuning process is to load my dsp5 with say five different injection maps say at 1 degree increments to get that dialed in first.. then do the same with boost, fuel pressure etc.
Timing for mileage:
Start with the factory mm3 table. (keep in mind not even the factory is "correct")
Build a DSP5 tune with nothing changed but the timing on the 4 extra tunes.
Datalog the mm3 with the cruise control set as you flip through the switch.
Vary speed and load and repeat.
Start with the factory mm3 table. (keep in mind not even the factory is "correct")
Build a DSP5 tune with nothing changed but the timing on the 4 extra tunes.
Datalog the mm3 with the cruise control set as you flip through the switch.
Vary speed and load and repeat.
so the mm3 data log is only comparable between tunes using the exact same pressure base? is that it? same procedure could be used to fine tune the other tables as well?
Mike what do you mean by 70/30 timing map??
Just what was said before, 70% BTDC and 30% ATDC. Naturally you DO NOT cary that amount of advance outside the areas where the truck is cruising, but it has given the best gains that I have seen personally. This and a few other tuning changes netted an LLY an average of 20 MPG at 80 MPH on the interstate over a trip of about 1500 miles, hand calculated. :thumb:
This is exactly how I do my tunes. I have a DSP2, but I don't ever use it, because my DD tune does everything from mileage to tow to (weak-ass) race, depending on how much pedal I give it.
FYI, there is a version of the timing calculator that lets you enter a percent for each cell, that's the one I use. It is WAY more useful than the old one with a straight percent.
I've been meaning to do that. I believe you could also use a modified mm3 table, so long as the only variable between the tunes was the timing.
I d/l the timing calc v3 and see the selectable % table now. So I loaded the current tune I'm working on into it and ouch! very high timing.. 100% in the cruising areas"1500-1800, 20-35 mpa". .. so I loaded a couple other tunes and even the stock tune to compare and they too have 100% events. Now I'm at a loss.. here I thought 70/30 was the way to go but even stock tune has more timing advance. I'n not sure where to go next.
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something cant be right.. either my truck is about to blow up with this current tune "runs pretty nice actually" or this calculator is making some screwed calculations. My current timing from 1400-2000, 20mpa is
6.8 7.9 8.8 9.3 9.6 9.7 9.7
If I put in a desired 100% timing I get
4.9 5.2 5.6 5.9 6.3 6.6 7.0
thats a 28% decrease!
if I put in the magical 70% desired BTDC i then get
3.4 3.7 3.9 4.1 4.4 4.6 4.9
doesnt that seem a little low?? whats going on here?
6.8 7.9 8.8 9.3 9.6 9.7 9.7
If I put in a desired 100% timing I get
4.9 5.2 5.6 5.9 6.3 6.6 7.0
thats a 28% decrease!
if I put in the magical 70% desired BTDC i then get
3.4 3.7 3.9 4.1 4.4 4.6 4.9
doesnt that seem a little low?? whats going on here?
No it doesn't sound low. What is your pulse width in those areas? You have to remember that there is a pilot injection event that will be getting pushed out by the same amount that you advance main timing injection as well. You don't want the pilot to occur at something like 60 degrees...something to think about.
pulsewidth at 20 mm3
0.000000 1500 1144 845 700 630 580 509 466 435 435 435 435 429 415 401
so what timing looks correct?
also, here is my FRP @ 20mm3 from 0 to 2000rpm
32.07 32.07 32.17 33.74 38.54 46.21 53.3 58.18 63.86 74.3
like I said earlier, even the stock tune has timing above 100%
1400-2000
7.008 6.141 5.906 5.906 5.906 5.906 5.906
true 100% according to the timing calc would be
4.9 5.2 5.6 5.6 5.5 5.8 6.1
but thats odd.. original values are decreasing and recalculated values are increasing?!
this calculator must be botched. anyone care to look? I'll upload the calculator with all values from stock 07 LBZ 6128 tune
0.000000 1500 1144 845 700 630 580 509 466 435 435 435 435 429 415 401
so what timing looks correct?
also, here is my FRP @ 20mm3 from 0 to 2000rpm
32.07 32.07 32.17 33.74 38.54 46.21 53.3 58.18 63.86 74.3
like I said earlier, even the stock tune has timing above 100%
1400-2000
7.008 6.141 5.906 5.906 5.906 5.906 5.906
true 100% according to the timing calc would be
4.9 5.2 5.6 5.6 5.5 5.8 6.1
but thats odd.. original values are decreasing and recalculated values are increasing?!
this calculator must be botched. anyone care to look? I'll upload the calculator with all values from stock 07 LBZ 6128 tune
Well you have to keep in that the different generation work differently. I guessing by your name you have a 06-07? I have my mileage tune posted in the library and have ran 12* before and it didn't rattle real bad. If you try my tune just make sure to run the other scripted I post later in the thread too.
did you d/l my attachment of the timing calc with data in it? Trying to figure out if I entered something in wrong or if there is a problem with the calulator.
I believe the timing calculator is working right. My tune also has above 100% for much of the cruise range. I wouldn't even worry about it if the timing is less than 10 degrees.
Do what McRat said and try different timing values. If you hear a rattle, back it off some. That is going to get you the best mileage. I personally don't use the 70/30 rule for cruise, I get better mileage with a bit more timing than that.
Do what McRat said and try different timing values. If you hear a rattle, back it off some. That is going to get you the best mileage. I personally don't use the 70/30 rule for cruise, I get better mileage with a bit more timing than that.
Thanks Dave, just wanted to make sure I didnt have some tables that were so far out of wack. There are no horrible rattles crusing.. although on a couple occasions runing cold shortly after cranking I heard a couple small "knocks".. in the data log it occured during a pilot injection event when decelerating. going to lower 0-10mm3 timing and also load up my dsp5 with 3 tunes with -10%, current, and +10% timing tables and observe mm3 during highway cruise to see where I need to move to next. I'll keep everyone posted
Oh, what you can do to keep the truck running right when it is cold, is adjust the timing modifiers by the same amount that you adjusted the bast timing tables.
I made a spreadsheet to do that, if you are interested. That way, your truck uses stock timing when cold, and transitions to the new timing as it warms up.
I made a spreadsheet to do that, if you are interested. That way, your truck uses stock timing when cold, and transitions to the new timing as it warms up.
I decreased the low alt ECT multiplier's by 25%.. so far so good.. didnt notice any pilot injection pings tonight. I also did some interstate logging today with my -10 and +10 timing tables.. with just a few miles I didn't see any significant fueling difference.. so this timing table must be pretty close on the money. I had to add another 5% to my T-vane tables because it was searching a little bit.. seemed to have that ironed out. anyone care to help build a custom PID so that we can get a more accurate fuel flow measurement and can tune the pulsewidth and fuel tables and not have to rely on a bad mm3 reading? I was thinking a conversion to gph so that a realtime mpg PID could be created as well. Any available flow data from bosch on our injectors?