宏虹診斷 | 2015 瑪莎拉蒂 GT 於 80 km/h 出現「嗡鳴聲」之振動噪音分析
Failure phenomenon
一輛 2015 年式 瑪莎拉蒂 GT，搭載 M139P 引擎，累計行駛里程約 13 萬公里。車主反映： A "humming" sound occurs when the vehicle accelerates to about 80 km/h.Replaced 4 tires, but the noise problem still exists.
NVH Troubleshooting
The technician uses the Acer Pico NVH diagnostic equipment to install the three-axis acceleration sensors on each of the three axes:
Driver's side seat rails, microphone fixed to the inner compartment 。
進行道路測試後發現：
The noise is most noticeable at approx. 80 km/h and is accompanied by a slight acceleration.
Fig. 1｜NVH Waveform
NVH waveform analysis: The collected NVH waveform is shown in Figure 1. When the noise is generated, the microphone signal (yellow color) shows a clear spike with a frequency of about 586 Hz and a sound intensity of 54.9 dB, accompanied by an obvious vibration response. In addition, the frequency of the spike varies with vehicle speed: when the vehicle speed increases slightly, the spike moves to the right and the frequency increases; when the vehicle speed decreases, the spike moves to the left and the frequency decreases. Conclusion: 1. Detects clear 586 Hz aliasing peaks. 2. Sound pressure up to 54.9 dB 3. The characteristic of "stable tuning" of the echoes, which increases in tandem with the increase in vehicle speed. 4. Frequency and sound pattern are in accordance with typical mechanical resonance noise.
The technician further used the "Band Pass Filter" function (retaining 520-610 Hz) to convert the microphone's continuous signal into an audio file and played it back to confirm that the band sound matched the owner's description of the anomaly.
Fig. 2｜Audio File Link ( Open WeChat and scan to listen )
And then.Use the 3-axis accelerometer as a microphone.The following are some examples of sequential measurements:
1. Automatic transmission housing
2. Rear Differential Body 3. Drive shaft suspension bracket 4. Wheel bearing position
Fig. 3｜NVH Waveforms on Rear Differential and Drive Axle Over-axle Bearing
The test results show that:The vibration signal is most pronounced at the rear differential position (Fig. 3).，而且異音頻率與前段分析完全一致。 因此推論：The source of the noise is the mechanical vibration and resonance noise generated by the rear differential.
fault resolution
changeRear Differential Assembly後進行回廠道路測試， 「嗡嗡」轟鳴聲完全消失，故障成功排除。
Fault Summary
本案例透過 Pico NVH 診斷工具的精準量測與頻率分析，成功將看似複雜的異音問題清楚量化，並逐步鎖定真正的噪音來源。從道路測試、頻段過濾、波形比對，到最終確認後差速器的異常，再到實際更換後完成排除，整個過程展現出系統化 NVH 診斷在車輛維修中的高效性與可靠性。 對技師而言，異音來源往往不容易以肉耳判斷；但透過科學化的 NVH 工具，即可將「聽不見的細節」轉為可視化數據，使故障定位更快速、更具說服力，也能有效降低誤拆、誤判帶來的成本。未來無論在車輛保修、異音分析或品質驗證領域，NVH 診斷都將持續成為不可或缺的重要技術。
