Ask Joe Mechanic: Current Recalls

We will return to our regular content next week.  This week will again feature the most current recalls that are listed on www.nhtsa.gov.  If after reviewing the recalls below, you discover that you own an affected vehicle, please contact your local dealer at your earliest convenience.  Your dealer will be able to tell you how to proceed with your automobile. 

This Week’s (11/4/14) Recalls:

Nissan North America, Inc. (Nissan) is recalling certain model year 2014 Infiniti Q50 hybrid vehicles manufactured December 10, 2012, to June 25, 2014, and Infiniti Q70 hybrid vehicles manufactured November 7, 2013, to May 7, 2014. Due to a software error, the electric motor may stop working while the vehicle is being driven using the electric motor only.  The stall-like condition that occurs when the electric motor stops working may increase the risk of a crash.

Nissan North America, Inc. (Nissan) is recalling certain model year 2014 Infiniti Q50 hybrid vehicles manufactured October 16, 2013, to January 27, 2014, and Infiniti Q70 hybrid vehicles manufactured November 7, 2013, to December 10, 2013. The affected vehicles may have been assembled with transmissions whose housings were damaged during their manufacturing.  The damaged housings could crack and fracture, creating road debris and disabling the vehicle, increasing the risk of a crash.

Toyota Motor Engineering & Manufacturing (Toyota) is recalling certain model year 2014 Toyota Avalon, Camry, Sienna, and Highlander and model year 2015 Lexus RX350 vehicles. Fuel may leak from the one of the fuel delivery pipes in the engine compartment.  A fuel leak in the presence of an ignition source increases the risk of a fire.

Chrysler Group LLC (Chrysler) is recalling certain model year 2014 Ram ProMaster vehicles manufactured April 23, 2013, to August 22, 2014. In the affected vehicles, the Tire Pressure Monitoring System (TPMS) may fail to learn the locations of the individual sensors while the vehicle is being driven. As a result, the low tire pressure warning light will illuminate, despite the the tire pressures being within specification. Should one of the tires lose air pressure, the driver would not be notified of the change in air pressure. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard No. 138, "Tire Pressure Monitoring Systems."  If the TPMS light illuminates because the sensors cannot be located, it could mask an actual low tire pressure condition, possibly resulting in tire failure, increasing the risk of a crash.

Chrysler Group LLC (Chrysler) is recalling certain model year 2010-2014 Ram 2500, 3500, 4500, and 5500 trucks manufactured March 27, 2009, to September 5, 2013. In the affected vehicles, the electrical connectors of the diesel fuel heater may overheat.  If the connectors overheat, the fuel heater may leak fuel, increasing the risk of a fire

Chrysler Group LLC (Chrysler) is recalling certain model year 2014 Dodge Durango, and Jeep Grand Cherokee vehicles manufactured October 3, 2013, to April 11, 2014. Due to an issue with the software for the Steering Column Control Module (SCCM), the Electronic Stability Control (ESC) may be disabled.  If the ESC is disabled during certain driving situations, the driver may not be able to adequately control the vehicle, increasing the risk of a crash.

Chrysler Group LLC (Chrysler) is recalling certain model year 2014 Dodge Durango vehicles manufactured June 2, 2013, to June 28, 2014, and 2014 Jeep Grand Cherokee vehicles manufactured October 30, 2012, to April 30, 2014. Due to a fault within the Occupant Restraint Control (OCR) module, the frontal air bags, seat belt pretensioners, and side air bags may be disabled. The malfunction indicator light “MIL” should illuminate to initially warn drivers of a failure.  If the frontal air bags, seat belt pretensioners, and side air bags are disabled, there is an increased risk of injury to the vehicle occupants in the event of a vehicle crash that necessitates use of the passive restraint system.

Mitsubishi Motors North America, Inc. (Mitsubishi) is recalling certain model year 2007-2009 Outlander vehicles manufactured December 15, 2006, to October 31, 2007, and April 16, 2008, to August 22, 2009. In the affected vehicles, the brake light switch may malfunction causing the brake lights to not illuminate during brake application.  Brake lights that are inoperative would not warn other drivers that the vehicle is stopping, increasing the risk of a crash.

Ask Joe Mechanic: Turbocharging Part II

We discussed in part 1 that turbocharging lately has become very advanced due to the governmental requirements to achieve higher gas mileage ratings. We now are finding turbochargers installed on V-6 engines which either necessitates some special designing to use only one turbo, or the use of twin-turbochargers.  With twin turbos on a V-6 engine, each manifold has a turbocharger installed on it and both feed into a single plenum on the intake manifold. This system is also used on boxer or flat engines such as Subaru uses. 

There are also manufacturers who are using twin-turbochargers in series to create higher boost at higher road speed, but eliminate turbo lag at low speeds. To accomplish this, a small turbo charger is installed first which will spool up quickly at low speeds. Then, there are specially designed piping leading to a second larger turbocharger for road speed. This type system is most commonly used on diesel engines, but some exotic car builders also use it.

            Another design is the twin-scroll turbocharger where there are two exhaust inlets in one turbocharger, with a smaller angled one designed for quick response and a second less angled larger inlet for peak performance. Usually, these twin turbos will pair cylinders 1 and 4 along with pairing 2 and 3 to more efficiently burn the fuel mixture and to reduce engine manifold temperatures. It will also greatly reduce turbo lag.

            Variable geometry or variable nozzle turbos adjust the amount of air entering the intake side of the turbocharger with a set of adjustable vanes. This will cause the turbocharger to operate at optimum pressure and efficiency based on the demand placed on it. There is an actuator which is computer controlled to move the vanes to increase or decrease airflow. By doing so, it will maintain the correct exhaust velocity throughout the engine’s power range and limit turbo lag.

            The center housing/hub rotating assembly (CHRA) is the most highly engineered and probably the most important part of the turbocharger. This section contains the lubrication, cooling and the turbine impellers and their mounting. The housing has ports for engine coolant to run throughout, and also oil passages to the bearing system. The bearings in most automotive turbochargers are either high-speed ball bearings or thrust bearings. In older turbochargers, the oil would sometimes become so hot that it would actually harden around the bearing, called coking, and this would cause the turbo to fail. This risk has been greatly reduced with better bearings, cooling designs and synthetic oils, which are more resistant to heat.

            One of the technologies that has been most effective in improving turbocharger performance is intercooling. The process of intercooling is basically forcing the air from the intake side of the turbo through a radiator in an effort to cool it as much as possible. The reason for this is that hot air is less dense than cool air and that loss of density means loss of power. When you force air through the turbocharger it builds up heat, plus it absorbs some from heat transfer from the exhaust side, so by going through the intercooler, it gives the air a chance to cool down before entering the engine.

            Another application that is used often by performance tuners is water injection where a spray of water is injected into the air charge to further cool it. A variation of this is to actually alter the air/fuel ratio by richening the mixture. The extra fuel does not actually get burned, but by turning the fuel from a liquid to a gas, it absorbs heat.

            The final add on feature to a turbocharger is a waste-gate. The waste-gate’s purpose is to regulate the pressure built in the turbocharger by regulating the amount of exhaust gas passing through the turbo. A pressure sensor sensing that the engine is reaching optimum boost pressure does this. The sensor sends a signal to the engine computer, which in turn sends a signal to a vacuum valve that opens and pulls vacuum, opening the waste-gate and allowing the exhaust gas to bypass the turbo.

Some information for this post was sourced from www.wikipedia.org.