2007 379 Idiling issue

Tiffany

Member
We purchased a 2007 379, with a 550 CAT we drove it home and was fine the next day noticed it was Idiling rough. Long story short after 4 loads we have had a complete over haul on it due to a cracked head. After new head, cam shaft, crank shaft, all new rocker arms, one injector, liners, pistons, wiring harness, alternator, fuel pump it is still idling rough. It runs like a beast, doesn't cut out when running down the road and will even idle up and not cut out. Not throwing any codes and even the CAT dealer didn't find anything when they checked it out. Timing has been checked, changed fuel filters, next is going to be throttle position sensor but out of the 4 mechanics we've had it to all of them are dumbfounded in what it could be. The motor has been combed through over and over and nothing has been found. If anyone has ever experienced this please HELP!
 

Goodysnap

Well-known member
You may be fighting a losing battle here. The first question that popped in my head is.... Engine rebuild and only 1 injector? How many miles are on the others? I don't buy the next day thing one bit either. It was like that when you bought it, you just didn't notice it. JMHO. Don't take it personal. I've rebuilt a ton of these, some come out smooth as glass, others have a shake to them. Just how it is. Seems worse on higher HP too. My advice, If its making good power and is not missing, Run it and live with it- or get rid of it. Don't waste you money on the TPS either. It wont fix it.
 

Truck Shop

Well-known member
Agreed, From the factory some just run alot smoother than others. You could chase that til hell freezes over, IMO.

Truck Shop
 
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Truck Shop

Well-known member
Wonder why?
Crank balance?
Piston and rod weight?
Deck height?
Sticking Kenüder valve?
Jason-I think most of it has to do with how equal the pattern of the injector is. The better the fuel is atomized the smoother it will run, plus better
mileage and power. And like anything no six injectors will spray the same-even new ones. IMO

Truck Shop
 
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