Last week I installed a set of DD3 injectors and tho I love the power with not a whole lot of smoke...I am having some idle issues...when i first start up and just sit idleing, or even after driving if I stop and idle for more than a minute...I get surging, i can hear the motor jumping rpms in a range of prolly only 25-50 rpms up and down, but you can hear it. And the tach shows it by surging up and a down just a little. It not so much that it causes any vibration, but it can be heard with the radio turned down.

Also when on the street, if i give it some go pedal at low boost, run some fuel thru it and leave a black cloud as I am accelerating, then i have to stop for a red light or something...sometimes it sounds liek the truck is gonna stall, its runs real rough, wont idle right, and the needle will jump all over. Usually to correct it I have to give it some pedal and hold it at nearly 1,000 rpms for a few seconds steady while in nuetral at a red light before it will calm down and idle somewhat normal other than the very slight surge metnioned above.

 

Sounds like the joys of owning a larger honed injector...not for sure though, I'm not not computer hampered (but I am undervalved )

I'm sure someone who knows more than me will chime in pretty soon...
Chris

 

Its a common problem with any injector. Honed or EDM. Several things come into play: The idle in the VP trucks is not mechanically controlled, but electronically. The ECM reads the inputs from the crank and cam sensors and adjusts the idle. I have noticed that trucks with slightly worn injection pumps that build less low speed injection pressures are the most sensitive. I have found the cure for a large percentage of the idle troubles with a pop pressure setting. I have chased it for literally a year now. Nozzle design plays a part as well so not all nozzle styles respond to the same pressure settings. The best advice I can offer is to have the pressure lowered some and see if it helps. Try 10 bar less than what it is now. Many times the trouble will never go away if the injectors are not evenly balanced in flow rate.

Don~

 

I cant say about the IIIs but with my IIs the only thing I noticed was the very slight surging when cold. On mine the tach wont move but I can hear it? Never had any rough idle or stalling. Sounds like maybe your getting air? Are you sure your injector lines are all tight? I have heard some people say it can take a couple hundred miles to get trapped air out of the system but I didnt have that problem?