The Chevrolet LT1 engine is the second-generation (Gen II) design of Chevy's famous small block. The LT1 was fitted in Chevy's Corvette, Camaro and Caprice/Impala SS. This engine also was used by Pontiac for the Firebird, by Buick for the Roadmaster and by Cadillac for the Fleetwood. The LT1 was first available on the Corvette in 1992, followed by General Motors' F-body cars (Camaro/Firebird) in 1993 and the B-body cars (Caprice/Roadmaster/Fleetwood) in 1994. The Gen II engine was manufactured in two displacements, 350 cubic inches (5.7L) and 265 cubic inches (4.3L). The 265 cubic inch engine was only available on B-body cars. Interestingly, unlike other Chevy small block designs, the Gen II engine was never available in any trucks manufactured by GM.

Diagnosing 1992-'93 Gen II engines is a little different from 1994 and later Gen II small blocks in that the '92-'93 units are controlled by a unique ECM. The '92-'93 engines are controlled by the ECM carrying GM service #16159278. These ECMs utilize a PROM chip for vehicle calibration, and fire the fuel injectors in "batch-fire" mode. The ignition system is GM's Opti-Spark system. Engines from 1994 and later use the newer flash-style ECMs, which still use the Opti-Spark ignition system, but fire the fuel injectors sequentially instead of batch-fire.

It is important to note that the newer ECMs contain a removable "knock" module underneath a small access cover. The...