Whistle Noise from the Throttle Body Area on Light Throttle Acceleration - kwidle intake manifold off accelerate GMT305 GMT360 GMT370 GMT800 GMT805 GMT806 GMT820 GMT830

The following diagnosis might be helpful if the vehicle exhibits the symptom described in the PI.

Some of the vehicles listed may exhibit a whistle noise from the throttle body area during light acceleration if they are equipped with a GEN III engine and an electronic throttle body.

This is a normal noise characteristic that could be experienced on these vehicles if they have an electronic throttle body. The same intake manifold design is used whether the engine has an electronic throttle body or a mechanical throttle body. Due to this, electronic throttle body engines still have an IAC passage in the intake manifold. The whistle noise may be the result of an airflow disturbance that can occur as incoming air contacts the unused IAC passage.

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Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed. If these steps do not resolve the condition, please contact GM TAC for further diagnostic assistance.

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(04 05 Buick Rainier S1, T1) and (03 04 05 Chevrolet Trail Blazer EXT S1, T1) and (03 04 05 GMC Envoy XL XUV S1, T1 01 02 03 04 05 Cadillac Escalade C1, C6, K1, K6 02 03 04 05 Chevrolet Avalanche C1, K1, C2, K2 01 02 03 04 05 Chevrolet Silverado Truck C1, K1, C2, K2, C3, K3 01 02 03 04 05 Chevrolet Tahoe C1, K1 01 02 03 04 05 Chevrolet Suburban C1, K1, C2, K2, C3, K3 01 02 03 04 05 GMC Sierra Truck C1, K1, C2, K2, C3, K3 01 02 03 04 05 GMC Yukon C1, K1 01 02 03 04 05 GMC Yukon XL C1, K1, C2, K2, C3, K3 03 04 05 Hummer H2 N2)