Hey guys I have this problem and its driving me nuts. I have a 2001 5.3 and it has a miss. I have changed the plugs and then the wires no change. So I had it scanned and the scan showed a miss on clyinder 6. So then I changed the coil and it still has the miss WTF !! I dont know what to change now, ecm mabey ?? Any ideas ?

 

injector.

 

If compression is good, that would be my next guess too.

 

definantly injector

 

is it A miss or several misses? when i had a bad injector i could watch the machine count every misfire as it was running. if its only A miss, clear the codes and watch it closely.

if your motor is running all lopy and sputtery, you need to clean or replace your injector. if its clogged that bad seafoam or techron based cleaner wont cut it. i got a can of cleaner made by 3m from the dealorship that i hooked directly into the fuel rail and i disconnected the fuel pump. worked like a charm.

 

When the truck is in gear and you just release the brakes you can feel a steady pulsing, after that you cant feel it any more. Full throttle seems ok.
The scan tool would show counts on cylinder 6 im not sure if it was evertime or not. when idling in park it is not that bad but it seems a bit rough to me. Could the wiring to the injector or the coil be bad or would this show a code.
The truck does not show any codes, this blows.

 

i'm having the same problem, i'm a try seafoam or something along those lines, and move from there, after i ohm out my wires this afternoon

 

well i had the exact same problem with mine. and i changed the wires and it didnt help but when i changed the plugs that cured it. what you may do is find cylinder 6 and pull that one plug out and put a new one in and see if that fixes it. cuz you could of got a bad new plug.

 

if i got a bad plug wouldent i notice it right away or would it slowly go bad? i'm new to these iridium plugs

 

You might only notice it under load, depending on what's wrong with it. If the gap is slammed shut, or the iridium tip broke off, it would misfire at all times. If the porcelain is cracked, it might miss at idle, or may need to be under load to notice it.