2004 IMPORT TECH REPORT

Motor,  Dec 2003  by Weissler, Paul

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The return of the Wankel, a refined gas/electric hybrid and several all-new models highlight this year's offerings from the import carmakers.

Creating totally different types of vehicles off a single basic platform is the most economical way for carmakers to cover a wide range of markets. The Japanese and Europeans have been honing this skill for years, and the 2004 model year is no exception. However, there also are some very new, technologically advanced vehicles coming to market.

The Mazda RX8 brings the Wankel rotary engine back to America in a brand-new four-seat sports coupe with Saturn-inspired rear access doors. The Toyota Prius gas/electric hybrid has grown up and gets major technology upgrades that make it a midsize mass-market car.

You'll be seeing other Toyota and Lexus cars in far greater numbers for many years, so their new technology is even more important to the technician.

Examples include widespread application of OBD II-CAN (Controller Area Network) diagnostics, so a CAN-capable scan tool is a must. And many Toyota/Lexus rear-drive automatics will not have: a transmission fluid dipstick, so require a high-tech check & adjust procedure, plus a totally new fluid.

The number of new models and new technology from European as well as other Japanese nameplates (even one "domestic") is awesome. The Jaguar XJ, Nissan Maxima and Quest minivan, InMu FX35 and FX45, Acura TSX and TL, BMW 5-Series and "Chrysler" Crossfire are just the standouts. You can't take a tech-service time-out.

Mazda

Mazda's new rotary engine doesn't develop quite as much horsepower as the twin-turbo of old, hut at 207 hp for the hase engine and 247 for the high-performance version, the coupe is quick. And with a price tag barely in the upper 20s, you'll see a lot more Mazda RX8 coupes than RX7 sports cars.

Without the turbos and other hardware, the new rotary engine is more compact (same height as the transmission), so for vehicle weight distribution it's moved 2.4 in. further to the rear than it was in the RX7. This puts most of the engine weight past the centerline of the front axle, a design Maxda calls "advanced front midship."

Wasn't the rotary having problems with emissions? Yes, but the new engine has a significant design change: The exhaust ports were moved from the rotor housing (the chamber periphery) to the two large, flat side housings, where the intake ports also are located. This larger space permits larger ports, plus tailoring their shape for both optimum performance and lower emissions.

Rotary engines respond well to multi-path air intake systems, even more than piston engines. The base engine has a three-stage intake system controlled by three flap valves, the high-output a five-stage intake controlled by six flap valves. The valve openings are computer-controlled according to engine rpm, with the intake runners getting shorter and straighter as rpm goes up.

Some aspects of the engine may bring back memories. There are two spark plugs for each of the two rotor chambers. Those plugs have an iridium center electrode and platinum-tipped side (ground) electrode.

There are two fuel injectors per chamber for the base engine, three for the high-output engine. The fuel injectors are not all the same. One has a 12-hole tip for ultra-fine atomization, and the other (or other two per chamber in the high-output) is a four-hole. The injectors are located in different places. With the high-output engine, the 12-hole is in the intermediate (inner) side housing, close to an intake port opening. The other two are in the intake manifold. With the base engine, both are in the intake manifold. The injectors pulse at different times, except at performance peaks, when both or all three inject at the same time.

The sealing of the rotor was a problem in older models, but new materials and improved designs help for the 2004s. Furthermore, the side location of both ports reduces the critical nature of the rotor apex seal.

Rotary engines run at high speed, and the new RX8 engine develops peak horsepower at 8500 and can rev to 9000 rpm, so engine oil cooling is important. The standard engine has a single oil cooler and a system capacity of 6.3 qts. The high-output engine has twin oil coolers (one at each side of the radiator) and a 7.1-qt. capacity.

The RX8 has electric-assist power steering-a ball screw drive on a rack & pinion box, with computer control based on inputs from vehicle speed sensor and the input torque by the driver on the steering wheel.

Tbyota/Lexus

OBD II-CAN diagnostics, which appears on many new Toyota/Lexus vehicles, can be read with a generic scan tool that has CAN capability. However, there's also an enhanced diagnostic mode, for which a "CANdi" plug-in module has been released. Vetronix makes the scan tool (a modified MasterTech) and the module, but the Toyota module is strictly for dealers at this time. Vetronix expects to release it to the aftermarket in the future, but a version of the software will appear in a future release for the aftermarket MasterTech, which gets its own generic CANdi module.