GMCtrk

iTrader: (27)

Whenever I am cruising on the highway I always notice a slight hesitation or hiccup every now and then. It's really subtle, but noticeable by me. No one in the passenger seat notices anything. It did this with the old 4.8 too, so the new motor has nothing to do with it. I'm not getting any codes or anything. Could it just be bad spark plugs? Ideas? Thanks

ricoc

I'ld try a little less timing in that area

COLDZ71

iTrader: (2)

Do you have efans?

lady3bglover

iTrader: (3)

Are the RPM's jumping?

JakeBrakeIH

iTrader: (22)

what year is the truck?

05GMCL33

iTrader: (2)

Do you run your a/c? I can feel my compressor clutch kick in and out and if feels just like what you described.

KySilverado

iTrader: (7)

I'd bet A/C compressor kick also. It drives me nuts!

COLDZ71

iTrader: (2)

Is it worse with efans? I never noticed it before I had them.

GMCtrk

iTrader: (27)

truck is a 2000. I have a clutch fan. And it does it when the AC is off, so it's not the compressor.

slow.8

my truck will hiccup ever so slightly when i turn the ac on, even with no belt on the compressor. it feels like the compressor is kicking on and of, which of course it isnt. i dont know if thats something in the tuning or what. its a constant thing until i turn the ac off.