mnpewter04
Full Member
Just got a Predator for Christmas, installed the 87 tune and noticed that I have lost 2-3 mpg according to the computer. Just wondering if anyone else has seen this with their installs?
-4 is too low! Check the Pred forums. Ideal is 0 to -2. If you're at +7 then it needs adjusted. Make sure you're following the proper methods for determining your LTFs. Monte is better at explaining this than I am but I know those are the numbers you're looking for.LornesAV said:I would think that would be in the instructions!
I just got my truck back with new pistons and rings. Gas mileage took a dive, 15 down from 17. I have an app that shows fuel trims short and long. The longs were at +7 and it look like shorts where hovering around +3. The shorts are kind of hard to read as the changed rapidly. All 3 different tunes available had the same results.
Trip before I had the pistons changed long trim was at a -4 and that was after drive quite a while with +4 for a while.
If your speedo is off, then that will account for some of your mileage. Is the speedo fast or slow?mnpewter04 said:Checked and do have the current tire size in the program. it should be entered just as the tire shows right? 265/70/r17. My spedo is also off by 4 mph but cannot seem to change it with the stock tires size entered.
mnpewter04 said:Speedo reads 60 and gps shows 56. Before the tune instant mpg on a flat road would vary between 19-21 and after it is 17-18 on the same road with same speed. I haven't changed any other perameters as I don't know what to change
mnpewter04 said:Speedo reads 60 and gps shows 56. Before the tune instant mpg on a flat road would vary between 19-21 and after it is 17-18 on the same road with same speed. I haven't changed any other perameters as I don't know what to change
MightyMouse said:If you're logging a +7 LTFT (Long Term Fuel Trim), that means you're running extremely lean, so the drop in mpg makes sense. Keep in mind that weather has a lot to do with LTFTs as the air gets more dense in colder temps, using less fuel.
If you've been running your tune for more than 100 miles and you're still showing +7 (using the Predator's data logging feature), go into the tune and adjust the injector slope by -7. Run it for 50-100 miles and log it again. You should be near zero in your LTFT.
Read the stickys on the diablosport forum as well. They'll help you a lot!
Good luck,
MM
mnpewter04 said:So i would need to do a data log, is this done while driving and hooked up to the predator? And is this adjusted in the performance tune?
Thanks
mnpewter04 said:So i would need to do a data log, is this done while driving and hooked up to the predator? And is this adjusted in the performance tune?
Thanks