haha i might just deal with the MPG i get to keep the truck quite or see if i can gain anything while keeping it quite.
Thoughts on fuel pressure and timing for a mileage tune
- Thread starter gmduramax
- Start date
The tow rig LMM has 30 overs and gets 21mpg on the freeway and is quite as a church mouse. And I run lots of timing. Well at least I think I'm am. Ill have to post up my timing table
Its been years since I felt there wasn't anything else I could do with MPG. I have changed my tunes since then some but best I can tell I added about 20KPa and took away 50us
Thats what I though, but thats not how my LBZ acted. I lost MPG as soon as I upped the RP and my logs showed it was running the same mm3. As best as I could tell. Its pretty hard to really tell though. As soon as I took out PW mileage went up.
Timing gained me the most MPG and that was mostly in city driving. My mods to KPa and US was only good for like .5 mpg hwy.
The problem is "True mm3".
When we build tunes we edit the mm3 table.
BUT ...
So does GM. If you do the math on the tables, you'll notice blips and bulges in the PW vs mm3. It appears that GM used it to fine adjust for final emissions and drivibility. In particular, check out the Van table. Wild.
So if you do the MM3 method, you first need to build a "clean" stock tune and take out the lumps. I built one years ago. I'll see if I can find it.
When we build tunes we edit the mm3 table.
BUT ...
So does GM. If you do the math on the tables, you'll notice blips and bulges in the PW vs mm3. It appears that GM used it to fine adjust for final emissions and drivibility. In particular, check out the Van table. Wild.
So if you do the MM3 method, you first need to build a "clean" stock tune and take out the lumps. I built one years ago. I'll see if I can find it.
I see no gains in taking away pulsewidth as it does nothing but the same thing as giving it less throttle. I didn't find any real gains in raising fuel pressure myself. I smoothed my rail table out some to get the valleys and dips out of it, added a few degrees of timing, and lowered my shift points. These changes did more for me than anything else. It's like pat said, it is all about true MM3 of fuel injected, and making the engine use it as efficiently as possible. It takes X amount of fuel to make Y amount of HP, and it takes Z amount of HP to push you down the road at a given speed. All you can do is to make more efficient use of the fuel being injected to get better mileage.
And as for timing at 100%, this is fine so long as it is in your cruise or low engine load areas of the table. you will find that even GM pushed up close to 100% on early trucks in the cruise and low power areas. Once you get above 40-50MM3 of actual fuel being injected is when you have to really worry about dropping your timing back into the 45-60% range.
And as for timing at 100%, this is fine so long as it is in your cruise or low engine load areas of the table. you will find that even GM pushed up close to 100% on early trucks in the cruise and low power areas. Once you get above 40-50MM3 of actual fuel being injected is when you have to really worry about dropping your timing back into the 45-60% range.
Lots of testing. Not very good results
Same here, though i did jump almost 2mpg with the new intercooler cause all my damn boost leaks are gone now lol
Still can't keep the EGT's down with this batmowheel. It runs cool while cruising but temps really rise if I hit any incline loaded or empty.
thats weird cause after my light tow out to the dunes, i never saw over 1100 and that was with me rolling into it pretty good in fifth up a 6% grade. im hooking the big trailer up Friday for a tow out to the dunes again and ill give you some feed back but already the intercooler and everything else done to the truck has really dropped temps. This summer will be the true test
Lots of testing. Not very good results
How much PW are you running in combo with FP at cruising speed (70mph)? Can you see drive pressure and EGT while you cruise? What is your average mph when calculating mpg?
I too have been playing around with trying to get the best mileage possible on my lowest power tune but the best I've been able to 16.7 mpg with 100 overs but I drive a mix of city and highway so my average mph was only 35 mph. This is down from the 18.4 mpg I used to get with the stock sticks...