2020 Corvette: GM TechLink: Misfire and Engine Noise Condition

2020 Corvette: Misfire and Engine Noise Condition

Some 2020 Silverado, Sierra; 2020-2021 Camaro; 2021 Corvette, Tahoe, Suburban, Yukon, and Escalade models equipped with the 5.3L engine (RPOs L82, L84), 6.2L engine (RPOs L87, LT1, LT4, LT2), or 6.6L engine (RPO L8T) may have a misfire and engine noise condition. The Check Engine MIL also may be illuminated along with possible DTCs P0300 (Engine Misfire Detected), P0106 (Manifold Absolute Pressure Sensor Performance), and P0506 (Idle Speed Low). These conditions may be due to a broken valve spring.

If it’s determined during an inspection that the engine has a broken valve spring, a cylinder leakage test on the affected cylinder must be performed.

5.3L and 6.6L Engines

On 5.3L and 6.6L engines (RPOs L82, L84 and L8T) built from June 1, 2020 to October 7, 2020, if cylinder leakage is not observed, replace only the affected valve spring. (Fig. 13)

6.2L Engines

On 6.2L engines (RPOs L87, LT1, LT4 and LT2) built from June 1, 2020 to October 7, 2020, if cylinder leakage is not observed, replace all valve springs on both cylinder banks.

Fig. 13

If there is cylinder leakage in the engine, perform further diagnosis to determine the extent of the engine damage and the correct repairs required.

For 6.2L engines (RPOs L87, LT1, LT4 and LT2) that have engine damage, follow the engine restriction procedures outlined in #PIP5759.

TIP: All valve springs are requested to be sent back for further engineering analysis and inspection.

If there is a valve spring concern, contact the GM Technical Assistance Center (TAC) (U.S.) or Canadian Technical Assistance Centre for assistance with issue verification and expediting parts if needed. U.S. dealerships should create a TAC DCM case before calling TAC.

For additional information, refer to #PIP5752E.

– Thanks to Bryan Salisbury