Silverado (Gen 3/4 V8 focus)
AFM/DFM patterns, misfire diagnosis under load, EVAP and fuel delivery checks, and what to confirm before blaming lifters or converters.
Open Silverado profile →Chevrolet (GM) Profiles
A starter set of high-signal Chevrolet diagnostics. The goal is repeatable reasoning: what to capture, what patterns mean, and what tests actually confirm the cause.
How to use these pages
- Start with codes + freeze-frame, then trims (STFT/LTFT), then misfire counters and O2 behaviour.
- GM platforms are sensitive to vacuum/PCV leaks, fuel pressure delivery, and electrical ground quality.
- Don’t condemn expensive parts (turbo, converter, lifters) until you’ve proven the conditions that point there.
Language note: petrol (gasoline) terminology is used where helpful so the site reads cleanly in the UK/EU and the US.
Models covered
Equinox (1.5T / 2.0T focus)
Trims-first turbo petrol diagnosis, PCV/intake leak patterns, boost control plausibility, and the common traps that waste money.
Open Equinox profile →GM-specific habits worth remembering
- Grounds matter. Strange sensor readings and intermittent misfires often trace back to voltage drop or poor chassis grounds.
- Fuel delivery is a frequent villain. A “looks fine” pump can fall over under load. Use commanded vs actual, rail pressure, and WOT behaviour when possible.
- P0420 is usually downstream. Fix misfire/trim/O2 control issues first; don’t start with a converter.