Genesis G70
A practical G70 workflow: decide mixture vs misfire first, then confirm boost/air measurement plausibility and EVAP behaviour before condemning expensive components.
Quick triage (5 minutes)
What to capture
- Codes + freeze-frame
- STFT/LTFT (idle and cruise)
- Misfire counters (if available)
- MAF g/s or MAP kPa at idle/cruise
- Commanded vs actual boost (if turbo)
- Battery voltage (engine off + running)
What it usually means
- Lean trims at idle only → intake leak / PCV / unmetered air.
- Lean trims under load → fuel delivery, boost leak, or air-measurement bias.
- Misfire with normal trims → ignition/mechanical; confirm before parts.
- Long crank after refuel → EVAP purge/vent behaviour.
Common TLX complaints (and the honest starting point)
- Hesitation under load: check boost plausibility and charge-air integrity first (pressure test) before swapping sensors.
- Intermittent rough idle: verify trims and EVAP purge behaviour; purge issues can mimic misfire.
- “Turbo feels weak” but no obvious faults: log boost request vs actual and trims—sensor bias can create a story that isn’t true.
- Multiple warnings after battery work: confirm battery coding/health and charging stability; low voltage causes cascades.
What NOT to do (high-confidence traps)
- Don’t condemn the turbo on an underboost code until you’ve pressure tested the charge system and verified sensor plausibility.
- Don’t replace coils/plugs repeatedly without repeatable misfire evidence (counters, load, temperature).
- Don’t replace a catalytic converter for P0420 until you’ve proven mixture and misfire are stable.
Typical OBD2 codes you’ll see
P0171
Lean Bank 1: trims-first plan that stops guessing.
P0299
Underboost: confirm leak vs control vs sensor bias.
P0300
Random misfire: separate mixture vs ignition/mechanical.
P0456
EVAP small leak: cap/vent/purge checks that save time.
Data that settles the argument
If you only log one thing: a short drive log with trims, MAF/MAP, RPM, load and boost request vs actual (if turbo). If the ECU is adding fuel and boost is low, you’re likely dealing with unmetered air or leakage. If trims are normal and boost data is inconsistent, suspect sensor plausibility.
Trust note: These profiles are designed to narrow possibilities. Confirm with test data (trims, misfire counters, pressure/smoke tests, voltage checks) before buying parts.