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PO300 OBD2 Code in 1997 Chevrolet Silverado 4x2 with 5.7L Engine - Diagnosis and Fixes

Model: 1997 Chevy Pickup Fault Code: P0300 Posted: 2012-08-26 18:19

I own a 1997 Chevrolet Silverado 4x2 with a 5.7L V8 engine and automatic transmission. Over the past 12 months, I've completed several repairs including a full tune-up using Advanced Parts brand components (cap, rotor, wires), Autolite Platinum spark plugs, and replaced a blown intake manifold gasket with a spider assembly sourced from a 1999 Chevrolet 5.7L engine. I recently started receiving a PO300 OBD2 code indicating a general misfire. Despite these upgrades, the issue persists. What should I do next? Any expert advice would be greatly appreciated.

Related fault codes

P0300

Comments (2)

Anonymous 2012-08-26 20:59

I recommend replacing the spark plug cap and rotor with OEM Delco parts. Additionally, switch from Autolite to AC Delco spark plugs. Aftermarket caps and rotors are known to cause issues on this engine model, and Autolite plugs are not compatible with the Bow Tie design commonly found in 1997 Chevrolet engines. This is where I would start—however, there may be other underlying causes contributing to the misfire.

Anonymous 2012-08-27 07:53

Agree on switching to AC Delco plugs. Please describe how the removed spark plugs appear: wet, dry, black, or tan? Always perform a fuel pressure test and a fuel system leak-down test. These diagnostics are essential for identifying misfire root causes. For reference: Is the 1999 CPFI fuel pump system operating at the same pressure as earlier models? * Fuel pressure gauges are often available on loan or rental—consider this a must-have tool when troubleshooting.