H2 Bang on Cold Startup?

[solarflare]

I've noticed now a couple of times, when I go out to start the H2, it makes a bang sound from the engine compartment.....only does this on the first cold start up. It's not a rattle or a tap...
It's when you turn the key, almost as though I'm not holding it long enough...???? Or, like the engine didn't shut off right....and gets back in sync when started.
Very hard to describe....but I remember my 05' did it a couple of times......anyone know what it is?

[BradO]

I had that happen as well. The truck seemed like it would almost lunge with a noise from the engine/drivetrain. Never checked it out, but since I changed the T-Case fluid (Royal Purple) it hasn't happened since (T-Case fluid was 65k old). Not sure if it's just coincidence or not. Been a few months.

[SmokeyJoe]

OLD POST

Anybody know what could cause this?

[charles06]

No idea, but I get it, too. Anyone?