Mileage Tune ???
If someone would be so kind as to explain to me how injection timing can effect mileage...
If someone would be so kind as to explain to me how injection timing can effect mileage...
Mileage Timing??
- Thread starter wdino73
- Start date
Start the injection event too late and the piston is running away from the fire (less push on the pistons... less efficient) Start the injection event too early and it will push on the piston before or at TDC and hurt power (efficiency)
Playing with injection timing can result in slightly better mileage due to having timing at it's most efficient spot... hard to know exactly what that is though!!
Playing with injection timing can result in slightly better mileage due to having timing at it's most efficient spot... hard to know exactly what that is though!!
^^ what he said
But it gets more complicated, because there is a lag for the injector to actually start spraying fuel, and the fuel sprays slightly differently at different pressures. So you have to correct a lag which is in ms, and convert it to degrees, and then think about what fuel pressure does to things.
It is no easy task! That being said, generally start bumping the timing up a little at a time until your mileage stops going up (or you get a rattle). Then back it off a hair. I have had good luck with 5-7 degrees in the cruise range (20-60 mm3 and 1600-2400 RPM), but it varies engine to engine some too. Some people (I am told) run 9+ degrees in cruise, so play around.
Good luck! Econ tuning can be a slow process; I like to run 1-2 tanks of various driving styles through each tune before coming to any conclusions.
But it gets more complicated, because there is a lag for the injector to actually start spraying fuel, and the fuel sprays slightly differently at different pressures. So you have to correct a lag which is in ms, and convert it to degrees, and then think about what fuel pressure does to things.
It is no easy task! That being said, generally start bumping the timing up a little at a time until your mileage stops going up (or you get a rattle). Then back it off a hair. I have had good luck with 5-7 degrees in the cruise range (20-60 mm3 and 1600-2400 RPM), but it varies engine to engine some too. Some people (I am told) run 9+ degrees in cruise, so play around.
Good luck! Econ tuning can be a slow process; I like to run 1-2 tanks of various driving styles through each tune before coming to any conclusions.
I want to say I'm up around 10-11 degrees during cruise iirc..... But I haven't looked at it with my HP Tuners scanner (because it blows).. just watching the insight. I'm also near 7000ft altitude. I have seen 24.5mpg on the highway
Wow! I never worked mine up that far, I stopped seeing useful gains after around 7 here at sea level. I'll bet your elevation has a bit to do with it. On a side note, I am always amazed how quiet my truck is when I get above 6000 feet.
Maybe I'll crank my timing up some more, I haven't messed with my tuning in over a month, I'll bet my FlashScan is lonely :spit: I'll try a couple tanks with the timing cranked and see what it does. Honestly, though, I am very happy with the mileage I do get (about 17 to 18 at 75+ MPH, with 285/75R16 tires and 8500-9000lbs curb weight).
What does your truck weigh?
Maybe I'll crank my timing up some more, I haven't messed with my tuning in over a month, I'll bet my FlashScan is lonely :spit: I'll try a couple tanks with the timing cranked and see what it does. Honestly, though, I am very happy with the mileage I do get (about 17 to 18 at 75+ MPH, with 285/75R16 tires and 8500-9000lbs curb weight).
What does your truck weigh?
You know I just looked at my maps and I'm only calling for around 7-8 degrees depending on rpm, mm3 etc in the cruise areas.... but I swear my edge was reading a couple higher than that... either my edge monitor is off or some corrections are cranking timing up a little. I'll check this out tomorrow evening and see whats up.
I'm guessing I'm around 6800ish (few things removed like tailgate, rear bumper for a roll pan, overloads, egr etc.) I have to drive it very nicely, and keep it around 65 to see that mileage though.
I'm guessing I'm around 6800ish (few things removed like tailgate, rear bumper for a roll pan, overloads, egr etc.) I have to drive it very nicely, and keep it around 65 to see that mileage though.
Thanks Guys, I know it's a bit tricky an there isn't a magic number,, I guess there's more too it than cutting back the pulse width, Do u guys raise rail pressure above 160mpa's or do u like it at 160, is there a point that pressure hurts, if u run say 1800 pulse width an 160mpa's on rail psi, then u raise the rail to 175mpa's then your putting in more fuel without raising pw. I'm I thinking right....
I played with timing and picked up some mileage.. but this thread got me thinking... I think now I'm going to start playing with fuel pressure.
I'm going to start out my smoothly raising pressure a couple % in the cruise areas and then smooth things out... I suppose that won't make much difference to start. I'm also guessing at some point when raising pressure, you are just wearing out your cp3 faster, and using up energy building higher pressures and not really benefiting anything anymore?? Anybody care to share what kinds of cruise pressures they have found to be beneficial??
I'm going to start out my smoothly raising pressure a couple % in the cruise areas and then smooth things out... I suppose that won't make much difference to start. I'm also guessing at some point when raising pressure, you are just wearing out your cp3 faster, and using up energy building higher pressures and not really benefiting anything anymore?? Anybody care to share what kinds of cruise pressures they have found to be beneficial??
Fuel mileage likes lots of timing, and lots of fuel pressure. I believe the best gains I have seen in mileage were using a 70/30 timing map based on pulse width and as much fuel pressure as you can stand the noise. I tuned an LLY locally here that averaged about 22 MPG on the highway at a cruise of about 70-75 MPH.
A bit off topic, but would any of you guys be willing to mentor me on this aspect of tuning? I've just barely started to mess around with EFI Live and could definitely use some sound advice. I'm averaging 16mpg every tank and it's killing me at 300+ miles every 5 days. I don't want anyone to write me a tune, but I would really appreciate the help.
send me your tune all I will look at it and make a few changes. Then you can load both tunes side by side and see what changes I made. Just to give you an idea. I can pm you my E-mail
well I built a new "mileage/DSP#3" tune out of my existing #2 and #3 tunes. #2 had slightly higher fuel pressure base and timing base B, but #3 had higher desired boost table. Take a look at this latest average.. 9.0 avg Inj timing " little more noticable engine noise, not bad at all". Odd part is the avg MAF went down from 19 to 17.. is this a good thing? Less air used to maintain a desired speed = better efficiency?
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I don't think looking at a log is a good way to tune for mileage especially small section of a log. Less boost(low vane %) equals better mileage but higher EGTs.
Why cant mm3 be used? If it is cubic millimeters fuel used per powerstroke, take and multiply RPM * 240 to get powerstrokes per hour then by your average or instant mm3 then divide by 3,785,411 to get gallons per hour. For instance, I turn 1800 RPM at 70MPH and average 27 Calc mm3 according to a recent efi live log.
1800 * 240 * 27 / 3,785,411 = 3.081 gal/hr
70 / 3.081 = 22.72 MPG
not too far off I think.. I'd like to create a custom PID in EFI Live scan to compute this on the fly.
1800 * 240 * 27 / 3,785,411 = 3.081 gal/hr
70 / 3.081 = 22.72 MPG
not too far off I think.. I'd like to create a custom PID in EFI Live scan to compute this on the fly.