Manual Motor Z22Se

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everal General Motors vehicles are equipped with a 2.2L engine called ECOTEC. This four-cylinder, fourvalves-per-cylinder, all-aluminum power plant was first installed in some Saturn models, beginning with the 2000 L-series. Saturn VUE and ION models followed. It was the optional engine in the 2002 Pontiac Sunfire and Grand Am, Oldsmobile Aleroand Chevrolet Cavalier and Malibu, and standard equipment starting in 2003. The ECOTEC is also used in the Saab 9.3. The ECOTEC engine uses a speed density-based fuel injection system, along with a waste-spark electronic ignition system. The waste-spark ignition is part of a unique Compression Sense Ignition (CSI) system that allows the powertrain control module (PCM) to determine proper enginephasing (cam position) without the use of a separate camshaft position sensor mounted near a rotating engine member. This article will explain how the CSI system operates. We’ll also document new misfire diagnostic techniques that are made possible by the system’s unique design.

Construction
The CSI system is a modular design, with nearly all the major ignition system components housed in asingle cassette (Fig. 1, page 44). The cassette is mounted directly over the spark plugs, with only connector springs and insulating boots to transfer the ignition energy to the plugs. The cassette houses two ignition coils. Each simultaneously sends ignition energy to two paired cylinders— one cylinder on its exhaust stroke and the other on its compression stroke. Cylinders 1 and 4 are paired asrunning mates on one coil and cylinders 2 and 3 are paired on the other coil. The cassette has an integrally mounted lead-frame and CSI signal plates, which serve to create the four CSI input signal capacitors. The CSI signal plate output node is connected through the cassette cover to the electronic ignition (EI) module by a dual female plastic connector cavity called an interconnect. The EI modulehouses the CSI signal processing compression sense time out (CSTO) chip, as well as

INVESTIGATING GM’S COMPRESSION SENSE IGNITION
BY JIM GARRIDO BY JIM GARRIDO This combustion chamber detective This combustion chamber detective uses ignition signatures to deduce uses ignition signatures to deduce engine phasing and cam position. We’ll engine phasing and cam position. We’ll show you how itgathers the clues. show you how it gathers the clues.

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the usual ignition primary drivers and current-limiting electronics. Before explaining how the CSI signal is acquired and processed to form the CAMOUT (engine phase) signal to the PCM, it’s necessary to understand the operating characteristics of a typical waste spark ignitionsystem. These operating characteristics are important because they directly influence the information contained in the CSI signal.

Spark Polarities
Fig. 2 on page 44 illustrates the 1/4 ignition coil firing events. One spark plug in the pair of DIS running mates always fires from the center electrode to the side electrode, while the other fires from the side electrode to the center electrode.One cylinder’s firing voltage rises in a negative direction, relative to engine ground, on the way to its final spark plug gap breakdown voltage. It then breaks quickly in a positive direction, back toward ground until the spark line is established. The running mate cylinder’s firing voltage rises in a positive direction, relative to engine ground. It then quickly breaks over in a negativedirection, back toward engine ground until the spark line is established. The polarity characteristics of the spark breakover events are one part of the information reflected in the CSI signal.

Illustration and design: Harold A. Perry; magnifying glass photo: Karl Seyfert; engine photo courtesy General Motors

Compression Sense?
As a DIS ignition coil releases its stored energy, an electric...