Detroit DD15 Rough Idle with no fixes yet.

Hello SLCTrucker, could you be more specific what part they replaced? Looks like my neighbor owns a Columbia has same problem with his Detroit motor. His truck already out of waranty. I would really apreciate your help.

 

Hello.. The valve he replaced is the high pressure fuel pump quantity control valve.. They are known for sticking and causing a surge.. the way to tell would be to open detroit diesel diagnostic link. you would open FSIC routing and compare control valve amperage as far as desired and actual they should be smooth and and not changing much at idle.. if they are acting erratic replace the valve

 

If anyone else needs a fix to this issue. It is the fuel quantity control valve. Part is about$711.00 labor is another 300-400. ItsI worth it, the cost of the fix pays for itsself because you will consistently get better fuel mileage. In just 4,000 miles you will save over $1,200 from the fuel economy imprrovment.

 

Its called the high pressure quality control valve its located behind the maint fuel pump and filter on driver side of engine part cost 500ish depending on where you get it and can be replaced at home in under an hour to save you nearly 1000 in labor regening.

 

Replaced the quantity fuel valve and it helped but still have a rough idle upon first start up if the day. Seems to smooth out after running for a while but still doesn’t idle like it should??

 

I’m thinking that fuel pump may need replaced??

 

Have you replaced the Damper on the crank. Replaced mine, smoothed out big time, then I did the FCV and this baby purrs soo smooth now. DD15 in a 4900 series