duramax lmm help

[ticketme]

Can someone please tell me why this tune "bounces" at 1100 rpm? By bounce i mean it feels like a tire is out of balance going down the road.

This tune is a 30% increase to injection duration, fuel pressure, and boost.

Also a 25% increase to timing.

This tune also only allows one pre-injection.

I get awesome fuel mileage with this tune, but it does not drive particularly well in the lower gears and rpm, like it is weak, or the turbo isnt spooled up. but i do not get any smoke.

Can someone please give me some pointers????

Thank you

This is a 2008 gmc sierra z71 4X4 with a k&n intake, mbrp straight pipe turbo back exhaust

trial7_2.zip

[Snipesy]

You applied your changes to everything. More timing isn't always a good thing.

So heres where I would do... You are getting better fuel economy. Revert the pulsewidth table back to stock. Revert the deired boost tables back to stock. For the timing and fuel pressure tables, revert them to stock, but keep your changes in the cruising range (1200 rpm to 2200 rpm, and 15 to 60 mm3 or so, not sure, but you've driven the truck so you should know). Then blend those changes so its not such a huge leap to the surrounding cells.

Then you should still be getting decent economy. If you aren't getting the same economy, give yourself a little more boost at the cruising range as well, but I don't think it'll be needed.