Detroit Diesel Series 60

I am resurecting this thread since there are now 2 trucks with what sounds like the same problem. I have spoken to the OP comparing notes neither of us has any clues nor have we been able to find anyone that can make any further suggestions. HELP!!! Please. Thanks

 

whats the fuel pressure?

 

Check fuel pressure after the secondary filter - Idle 15 psi - no load rpm 65 to 70 psi

 

if the fuel pressure check is good with engine under no load then need to drive it and see what the pressure is doing, it was said that it was missing under a load. make sure the pressure doesn't drop while driving. I just replaced a fuel pump on a detroit thats had similar issues due to a weak fuel pump. like bush chook said it needs to be on the outlet of the secondary filter so you know what the pressure is going to the head.

 

Like Pheebo I can hear the "miss" at all times (idle, bobtail or full load hard pull). Wiring harness's have been replaced. I will check fuel pressure but doubt that is what it is since it is there at all times when you know what to listen for. Had clutch and drive shaft checked for damage, U-joints, etc. No codes. Power does not seem to be down though I have not dyno'd it. Also sound is consistent as though directly related to one single cylinder. (However I am not completely convinced it is internal problem.) Not intermitent or varying in any way. Vibration caused by this becomes worst at 1400-1650, more pronounced at some RPM's than others but always there. Similar to an out of balance tire at changing speeds. Thanks

 

7mouths2feed-have you had a injector cut out performed on the engine yet, the cutout test will help to isolate a problem cyclinder if there is one, then you will know to invest time there.

 

Yes had injector cut out done. My first thought was Bad Injector so that was were I started. All injectors tested good at low (650 rpm) and high idle (1000 rpm). Let me add that turbo pressure max's out at 24psi.

 

when you perform the injector cut out, did the miss go away at all? cut the injector out and rev the engine or just let it idle, listen to the pitch change in the engine, rev the eninge with each cyclinder cut out, listen for the miss, see if it goes away or changes, this will help to isolate a cyclinder. make sure the basic checks have been performed like fuel pressure check-and i dont mean from a fuel pressure sensor, needs to be with a gauge, air filter isnt clogged, visual inspection of top end and overhead checked and set if needed.

 

You can also try this trick. With the truck running at idle if you can hear or feel the miss lightly put pressure on the steering wheel Not really enough to turn the wheel just some pressure. If the miss smooths out or changes you have injector problems.

 

Broken valve spring?