OVERVIEW
With another round of refinements for model year 2001, the 3.4-liter, 60-degree LA1 V6 has been prepared for a new application in the new Aztek compact sport-utility vehicle.
NEW OR CHANGED FOR 2001 MODEL YEAR
* More Efficient Catalytic Converters
* Air Gap Downpipe
* Intake Valley Baffle
* Modified Lifter Guide
* More Durable Water Pump
* Improved Bearings for Accessory Drive Belt Tensioner and Idler
* High-Resistance Spark Plugs and Wires
* New Starter Motor
* Sleeveless Coolant Sensor
* On-Road Vapor Recovery (ORVR) System for Montana and Aztek
* Specific Oil Pan for Montana and Aztek
* Revised Powertrain Control Module (PCM) for Aztek
CUSTOMER BENEFITS
BETTER CATALYSTS
Improved technology increases the catalytic converter's efficiency, allowing National Low Emission Vehicle (NLEV) certification with considerably less catalyst volume and lower cost. Improved production methods allow a thin-wall catalyst substrate and new catalytic coating application. These techniques mean improved performance with less platinum, palladium and other precious metals in the catalyst. Converter volume has been reduced from 163 ci to 116 ci in the Grand Am, and from 163 ci to 134 ci in the Montana. The 134 ci converter for the 2001 Aztek is supplied by Zeuna Starker.
AIR GAP DOWNPIPE
An air gap downpipe connecting the exhaust manifolds with the catalytic converter, used on engines for California and select Northeast states for model year 2000, is applied to all LA1s. The pipe has dual walls separated by a jacket of air, and heats more quickly than conventional single-wall steel pipe.
Combined with more efficient catalysts and a new Denso forward oxygen sensor with a 6.6-watt heating element, the air gap downpipe speeds emissions light-off time by as much as five seconds. As a result, in passenger car applications the LA1 needs no Air Injection Reaction (AIR) for National Low Emission Vehicle (NLEV) certification. Eliminating the AIR system eliminates assembly parts and reduces cost.
LA1s for the Montana and Aztek carry over with AIR, and are Ultra Low Emission Vehicle (ULEV) certified in California and select Northeast states.
VALLEY BAFFLE
A baffle in the intake manifold valley protects the manifold gaskets from direct contact with engine oil, reducing the likelihood that the gaskets can saturate with oil.
LIFTER GUIDE
Valve lifters are now pre-assembled with the lifter guide, removing a step from the engine assembly operation and improving efficiency. Further, each guide is fitted with a plastic shield that, with the new intake manifold valley baffle, virtually eliminates the possibility that manifold gaskets can be exposed to oil. This protection removes a potential leak source.
WATER PUMP ASSEMBLY
The seal on the water pump shaft is made of more durable hard carbon silicon carbide. Further, the pulley bearings are sealed. Together, the improvements extend the water pump's useful life and reduce the potential for leaks.
DRIVE BELT TENSIONER
Bearings in the accessory belt tensioner and idler, which maintain proper belt tension without adjustment, are now validated to 150,000 miles of service. The permanent lube in the bearing maintains its lubricating properties longer. Further, the bearing seal is improved to keep the lubricant in and water, dirt and other contaminants out.
IMPROVED PLUGS AND WIRES
New high-resistance spark plugs and wires virtually eliminate the possibility of radio interference. The plug wires are soldered rather than snap-fit at the connector inside the plug boot. Soldering improves reliability and decreases assembly errors by reducing the possibility that the plug wire can inadvertently be detached from the connector. Finally, the Delphi spark plugs have silicon coated platinum tips to reduce fouling and the likelihood of service over the 100,000-mile plug life. The coating is particularly useful during post-production marshalling, when cars are started frequently and run briefly, and reduces the likelihood of pre-delivery plug cleaning at dealerships.
STARTER
The new starter motor, supplied by Delco Remy America, draws less amperage than the starter used for model year 2000, yet delivers the same cold cranking power. That means the same starting power with less drain on the battery. The new starter is also lighter, and costs less to manufacture.
COOLANT SENSORS
The coolant temperature sensor uses a plastic insulator to protect electrical leads inside the brass housing, rather than a rubber sleeve. The new sensor reduces the possibility of assembly rejection or shorting in operation. The low-coolant-level sensor is deleted on LA1s for Montana.
FULL ORVR APPLICATION
The Montana and Aztek are equipped with an On-Road Vapor Recovery System that keeps gasoline vapor from escaping into the atmosphere. The evaporative canisters on the Venture, Silhouette and Montana have a capacity of 2.1 or 3.1 liters, depending on fuel tank capacity. The canister on the Aztek has a capacity of 2.1 liters.
AWD MODIFICATIONS
LA1s for Montana and Aztek are fitted with a model-specific oil pan. The pan has special bosses to accommodate a brace for the power drive unit on vehicles equipped with all-wheel drive. Further, the Aztek has a revised transmission bracket with an additional "pencil brace" to secure the power drive unit.
REVISED PCM FOR AZTEK
The Powertrain Control Module on LA1s for the Pontiac Aztek adds additional software to monitor sensors and manage the optional all-wheel-drive system.
CONTINUING FEATURES
Revisions for model year 2000 enhanced performance and durability in the 3400 V6. The cylinder heads and oil pan were fitted with new, leak-resistant gaskets. New Multec II fuel injectors improved fuel efficiency by making fuel delivery more precise, and reduced the likelihood of injector clogging. Fuel pressure was increased from 300 to 380 kPa for improved hot starting. A number of enhancements reduced internal engine friction, in turn reducing noise and improving fuel economy. Those included reduced friction piston rings, revised cam profiles and a new cam gear and drive chain.
The 3400 V6 was developed for the 1997 Montana. It shares its engine block with the 60-degree LG8 V6, increasing displacement 200 cc by increasing cylinder bore three millimeters. The LA1 was first used in a passenger car in the 1999 Grand Am.
"With the 3400, we are definitely serving up a good engine for the cost of production. It works because it satisfies customer demands with low cost of ownership. Platform teams want it for exactly that reason." --Mike Parise, Model Year Manager, 60-degree V6 engines.
LEADERSHIP
The LA1 proves that refined overhead valve technology, continually improved, meets customer needs for good specific output, a broad torque band, economy and durability at reasonable cost to both the corporation and the customer.
"Need power? All GM minivans have a 180-hp, 3.4-liter V6 with 205 lb-ft of torque that's more powerful...than Chrysler's optional 3.8-liter V6.
--AUTOWEEK'S 1998 BUYER'S GUIDE
