Duramax LB7-LMM (2001-2010): misfire, rough idle, hesitation or surging

2 documented failures on this engine list this among their signs. They are ordered from the most widespread down. Each one shows the signs in its record's own words, how to tell it from the others, the usual fix and any recall or bulletin.

LB7 injector failures (the defining repair of the generation) Common
VGT turbo vane carbon / actuator wear (LLY+) Occasional

Not sure which engine you have, or want the recalls for your exact truck? Check your VIN: it names the engine and lists the campaigns for that model year. Whether a recall is still open on your VIN: nhtsa.gov/recalls.

1 LB7 injector failures (the defining repair of the generation)

aggregated How widespread: Common

How it shows up

hard starts / extended crank, white smoke, rough idle on 2001-early 2004 trucks

Its other signs

fuel dilution of the oil, cylinder contribution imbalance
documented across the era - the history source itself cites the LB7 injector problems

How to tell it apart

cylinder contribution test before ordering a set
check return-flow rates per injector to isolate offenders
on a failed injector: flush/inspect the fuel system - contamination kills the new set too

Usual fix

replace failed injector(s) or the set; keep the fuel system clean and consider contamination protection on a repair

Root cause, parts and sources →

2 VGT turbo vane carbon / actuator wear (LLY+)

aggregated How widespread: Occasional

How it shows up

boost flutter / hesitation, limping boost control

Its other signs

slow spool, smoke under load

How to tell it apart

verify vane movement (solenoid command vs actual) before ordering an actuator
rule out boost leaks and air filter restriction first

Usual fix

service: desoot/clean vanes, replace actuator or turbo assembly as inspection dictates

Root cause, parts and sources →

Other symptoms on the Duramax LB7-LMM (2001-2010)

White smoke from the exhaust Losing coolant

Everything on the Duramax LB7-LMM (2001-2010)Its recalls and bulletins

Order: how widespread each failure is in its record (near-universal, very common, common, occasional, rare), then the number of NHTSA owner complaints that match its keywords. Complaint counts are keyword matches, not a manual review of each complaint. A symptom listed here means the failure is documented with that sign; it is not a diagnosis of your truck. Tiers: verified, aggregated, contested, data-gap. How we tier and source facts.