Hang on. Holding place to type huge explanation
Ok here goes. Mine does it too. When it's cold (depends on the temp for each truck, mine is a wimp so 35-40 and down is hard), the oil is cold, so thick, so doesn't flow fast at all. Like cold molasses. But when you plug in the block heater, it does just that: heats the block. Which contains oil and coolant as well as the cylinders so everything flows nicely and combusts nicely too.
Well on each head there is a high pressure oil rail that feeds the injectors. The rail is only so big so cold oil can only flow down to the end so fast. AND it's a dead head rail, just an end, no loop. Oil enters near the front of the cylinders (#2 on the driver side) from the HPOP and gets pushed to the back (#8). Well in the firing order, #8 is RIGHT AFTER #6. So once 6 fires, it depletes what oil there is in the general area. Since the oil is cold, thick, slow, the HPOP can't push enough oil ALL THE WAY to the back of the rail to the 8 injector fast enough before that one fires, so it gets an incomplete injection. Just a normal engineering hiccup right and just has to be that way right? No.
You can either get some synthetic, an oil with a lower weight for the winter, or both. OR you can get a HPO Xover hose. Just bridges the two oil rails at the #3 to #6 cylinder area. So once #6 fires with that thing installed, you have oil coming from the HPOP AND the passenger oil rail to help replenish the rail before #8 fires. Smooths the idle, ESPECIALLY in cold starts. Makes it quieter. Keeps the RPMs very very steady. Had it on a dyno pre and post HPO Xover install. Pre install the RPMs on the comp were varying by about 50 or so. Post instal, didn't move at all. Ok, maybe 2-3.
Last edited by jesilvas; 11-30-2010 at 05:41 PM.