electronics, "Pulse-Air", and an increased compression ratio, from 8.6:1 to 9.2:1. The fourth version followed shortly. Maintenance The system uses a maze of emissions vacuum hoses. Because of the many vacuum-driven components and electrical connections in the system, CEC-equipped engines have developed a reputation of being hard to tune. American Motors issued a Technical Service Bulletin to diagnose low or inconsistent engine idle speeds on 1980 through 1988 AMC Eagle automobile. The 49-state model of the CEC has no on-board diagnostic system, making it difficult to monitor the computer's operation without a breakout box, and the Carter BBD carburetor on most CEC-equipped models has problems with its idle circuit clogging, causing a rough idle and stalling. In places where emissions testing is not required, a modification is by bypassing the computer and disabling the BBD's Idle Servo, or replacing the BBD with a manually tuned carburetor. Several vendors (including Chrysler and Edelbrock) offer retrofit kits that replace the CEC and the carburetor with fuel injection. References External links , a guide to the CEC system and how to tune it. Engine control systems Computerized Engine Control Computerized Emission Control Engine technology Engines Automotive technology tradenames