Cost-Effective Engine Diagnostics for Production Engine Hot Test

Quality is the number one priority at Ford Motor Co. To adhere to the best in class (BIC) engine quality standard, current manufacturing processes and controls are based on the philosophy of defect prevention and not detection. One such control is the critical gaging operations, checking tolerances to .0005″. “Out of specification” tolerances may cause abnormal engine noise and vibrations. Therefore, to rapidly and effectively determine abnormal engine noise, a method using accelerometers and cost-effective electronic signal processing techniques was developed. This paper describes an overall approach to the characterization of specific engine anomalies through the use of frequency domain signal analysis techniques. To apply this technique “mis-built” (out of specification) production 5.0L V8 engines were assembled at Cleveland Engine Plant No. 1. The results of this study and the development of an inexpensive electronic module to detect engine noise are presented. Also included in the paper is a method to isolate component noise to a specific engine cylinder, providing additional diagnostic capability. Benefits of the application of these techniques are also discussed.