They multi fire the injectors each stroke to help with the noise and emissions. .
also found it interesting that the square tubing frame only goes back to the rear axle then they have channel welded to the frame the extends the rest of the way to the bumper. Does anyone have any idea why they would do that ?.
they have had "multi fire" as you call it injectors since 01 its called "pilot injection" this helps control where the combustion takes place in the cylinder. the 4 and 6 cyld durimax units have injectors that are capable of up to 5 events per cycle.
the frame is made that way so that if you get hit hard in the rear the frame can be sectioned out and replaced, im not sure about 1 tons but they have been doing that since 99 when hydroformed frames came out. my wife had a 99 and got hit in the rear on the highway and they replaced that section of frame.
home link is cool as long as you have a newer garage door, navigation is awsome i had it first on my denali and now on my 07 "new body" sierra.
happy smokin diesel guys