So my sig truck has been having some issues lately. It misses when cold and then smooths out like always, but now and then when under load i can hear and feel a dead hole. sometimes i can hear the exhaust popping, other times after hauling a trailer i can be sitting at a light and hear it missing. I thought it was an injector and pulled all the old ones and put in the 120 sticks and i didnt hear it for awhile, and just today while towing it came back and feels worse than ever, while running through the gears it was shaking the truck.

 

how many miles do you have on your engine and do you have any fuel dilution with your oil and you said it does when you start it check and see when you start it if it has a cold cylinder by placing a hand on each exhaust port and see if ones not hot or loosening each injector line at the injector and see which one doesnt cause it to miss

 

Sounds like one of the injectors are getting fouled by contamination, have you checked for any debris in the fuel filter? The popping out the exhaust would be from a late or incomplete fuel burn or a sticking valve. Have the injectors been pop tested lately?

 

have you advanced your timing? it will pop out the exhaust and smoke white

 

Almost 290k on the motor, I will try feeling the exhaust ports and check the filter (that needs to be changed anyways)

Smoke is always black, no white even on cold starts.

 

Just felt the exhaust at idle all are warm, then took it for a haul and came back and all are the same temp. Filter next