Engine-Related Shudder Concerns

A shudder or surge may be felt when driving at a steady speed on some 2014-2022 Corvette, Silverado, Sierra; 2015-2022 Tahoe, Suburban, Yukon, Escalade; 2016-2022 Camaro; 2020-2022 Silverado HD, Sierra HD; 2021-2022 Express, Savana; and 2022 CT5 models equipped with the 4.3L engine (RPO LV3), 5.3L engine (RPO L82, L83, L84), 6.2L engine (RPO LT1, LT2, LT4, L86, L87) or 6.6L engine (RPO L8T). The shudder condition may be caused by the camshaft actuator magnet sticking. (Fig. 7, #2)

Fig. 7

Before making any repairs, determine that the condition is engine related and is not caused by the transmission. Monitor the Camshaft Position Variance data parameter in GDS2 while duplicating the shudder condition. The target variance is 0 degrees, but a variance up to 3-4 degrees may occur on a properly functioning system. Any variance exceeding 3-4 degrees may potentially cause a noticeable shudder or surge condition.

Following are line graph examples from GDS2 of the camshaft actuator system showing normal operation (variance under 4 degrees) and improper operation. (Fig. 8)

Fig. 8

If the concern is isolated to the camshaft actuator system, replace the camshaft actuator magnet and evaluate system operation. Refer to Camshaft Position Actuator Magnet Replacement in the appropriate Service Information.

For more information and part numbers, refer to Bulletin #22-NA-080.

– Thanks to Bryan Salisbury

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