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(Off Topic, but) Question about 2015 Malibu Start/Stop Feature


Service1956

Question

Wife wants a new Malibu. The only thing that concerns me, is the start/stop that this car has. The only thing I cannot help to think about, is the idea of having to replace the starter in it more often then normal! That, and the small battery that powers the electrical items during a stop (engine shut down). It would also seem like the main battery would have a shorter life as well.

 

Any comments from people that possibly would know more about this system?

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The current start/stop system on the 2.5 is not something you would even notice in the engine compartment from what I can find online. It is a mechanically simple system, shuts off when stopped (and all other parameters are met), then starts engine once brake is released(or other parameters are met). Dual batteries are likely the only give away. Did not find how it is handling the vacuum in the brake booster with engine shut off. Does it use a vacuum pump instead of engine vacuum now? Otherwise the driver will not have power brakes available if they shift their foot around while stopped. Or they will have a very short period of no power assist while engine is restarting. I am describing what would happen when you are sitting at the lights and alter your foots position on the brake pedal.

 

I was standing at a corner downtown recently next to a stopped car with the stop/start system on it. I found the sound of an engine starting when you don't expect to hear it a bit unnerving.

 

Going a bit off topic here, but, anyone know whatever happened to the lithium-iron batteries that were coming out a few years ago? These batteries were a lot lighter than AGM, smaller dimension as well. Last I saw they were coming out for bikes, but seem to have disappeared.

Johnson controls touts the AGM battery developed for the start/stop setup as ideal for the deep discharge scenarios. Did check out the owners manual for a new Malibu. Seems to only allow 2 or 3 minutes of stop time and monitors battery condition to keep it from getting out of sorts. Was kind of curious on something. The starter for the new model is only slightly more expensive than the outgoing model and there is a separate alternator listed. Here is an excerpt from C&D

"The Impala LS and LT Eco trims–each $2000–$2275 dearer than their gas-powered LS and LT counterparts—make up fewer than 1 percent of all Impala sales–will be discontinued. Not everything eAssist is dead, however—the setup’s heavier-duty starter motor and electric transmission pump carry over to the new stop-start system, just as they did in the Malibu. (The system also lives on in the Buick LaCrosse and Regal.) Also similar to the 2014 Malibu, the Impala’s stop-start system will be standard on all models utilizing the base 2.5-liter four-cylinder engine. Stop-start boosts four-cylinder Impalas’ city fuel economy estimates by 1 mpg, to 22 mpg city; the highway estimate remains 31 mpg. (The Impala with eAssist, for reference was EPA-rated for 25/35 mpg.) For this mild improvement, the Impala’s base price rises a negligible $65 to $27,735. The fuel-saving tech won’t be available on Impala models with the 3.6-liter V-6, which GM attributed to development costs and software changes that haven’t been applied beyond its 2.4-liter and 2.5-liter Ecotec engines.

General Motors didn’t simply add stop-start and call it a day, however; the automaker added some clever features to ensure the operation is as seamless as possible. For example, the Impala, uses specific motor mounts to quell vibration, while stop-start’s electronic brain is smart enough to keep the engine running if the car doesn’t reach 6 mph—a welcome feature in crawling traffic where continuous stop-start cycles cause us to tear out hair. Like Ford, which has pledged to add stop-start systems in 70 percent of its lineup by 2017, GM said it was considering other models but wouldn’t name names."

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It is a stout system. Haven't seen any in yet with issues.

 

http://sandyblogs.com/techlink/?p=4453

 

and:

http://media.gm.com/media/us/en/chevrolet/vehicles/malibu/2015.html

 

Stop/start technology enhances efficiency
Malibu has two powerful and efficient powertrain offerings: the standard 2.5L iVLC (intake valve lift control) with stop/start technology and a 2.0L turbo. The stop/start feature on the 2.5L shuts down the engine in certain driving conditions to reduce fuel consumption. Along with other technologies, including direct injection, variable valve lift control and a six-speed automatic transmission, the 2.5L powertrain contributes to EPA-estimated fuel economy ratings of 25 mpg in city driving and 36 mpg on the highway.

There are no buttons to push or procedures to learn with Malibu’s stop/start system. It automatically shuts down the engine when the car comes to a stop under certain driving conditions, such as a stoplight. The engine automatically restarts when the driver takes his or her foot off the brake. The system monitors vehicle speed, climate control system operation and other factors to determine whether it is efficient to shut off the engine.

Unique components used with stop/start include:

  • A tandem-solenoid starter that enables the engine to restart more quickly and more smoothly – even if the engine hasn’t come to a complete stop
  • An electrically driven transmission auxiliary hydraulic pressure pump that keeps the fluid in the six-speed automatic circulating and primed for immediate take-off when the driver removes his or her foot from the brake pedal
  • Larger, 12-volt absorbent glass mat (AGM) primary battery – which delivers up to four times the typical life cycle of a conventional battery – and a small, auxiliary 12-volt AGM battery
  • Dual-battery isolation module that ensures both batteries are properly charged and the primary battery always has a sufficient charge to start the vehicle
  • Torque-reaction engine mounts that dampen the vibrations associated with a restart, helping deliver smooth, nearly imperceptible performance.

The 2.5L is SAE-certified at 196 horsepower (146 kW) and 186 lb-ft of torque (252 Nm). Revised transmission shift points and quicker shifts also enhance the feeling of performance – while delivering greater refinement.

The Malibu’s available 2.0L turbo engine delivers nearly 14 percent more torque than its predecessor– SAE-certified 295 lb-ft (400 Nm). Revised engine calibration accounts for the improvement, making the Malibu 2.0L turbo’s torque the best in the segment, even among six-cylinder competitors. The result is a stronger feeling of acceleration from a stop and a greater feeling of power on demand in almost all driving conditions. The 2.0L turbo also produces an SAE-certified 259 horsepower (193 kW).

 

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