LB7: White smoke at rough idle, no power

[Milenko]

Hey all,

Have a 2004 LB7 with some serious problems. It's got a really smokey rough idle and no power at all. Right now it's to the point where it's almost undriveable because it can't get out of its' own way.

I work at a school and our auto shop has a tech 2 which I hooked up this afternoon to check balance rates. All of the injectors where +-1 from zero except for 5 and 7 which were +4.5 and -3.6 respectively. Fuel pressure at idle was 6500 and I commanded it up to 18,000 psi at 2000 RPM and it held steady. This not under any load, but still.

It has only thrown a CEL once since this started, pulled codes P0087 and P1093 which look both related to low fuel pressure in the fuel rail.

Any ideas? Balance rates aren't that far out of whack from speck and fuel pressure seemed ok at idle, so I'm kind of at a loss as to what to look at next.

 

[Muff]

stock injectors?

 

[jojo]

Fuel pressure regulator or cp3. If the engine is puffing out white smoke it may be that bad injector. All it takes is one bad injector.

 

[Burn Down]

Ck your cp3 (fuel pressure) at idle you should be able to command 24,000 or close to it. No need to rev the engine up. Also put the truck in gear at idle, the load on the engine sometimes helps bad injectors show up.

Any fuel in the engine oil? What mods are on the truck? How old/miles are on the current injectors?

 

[Kappa9012]

it sounds like you have two bad injectors, but you need to check the fprv, you can also plot the fprv command % if its jumping around a few % that's a sign that it's struggling to hold a steady pressure and needs replaced.

 

[MACKIN]

White smoke is unburnt diesel fuel as long as it is fuel related. Make sure you aren't making oil either pull the dipstick. Sounds like bad injectors

 

[juddski88]

Balance rates may sometimes help you isolate a problem, but they Dont tell the whole story. I agree that it is probably bad injectors, but you may find other issues once those are replaced and diagnostics is finished.