Mazda: Breaking New Ground In Torque Steer?

Edward Niedermeyer
by Edward Niedermeyer

Among the many new SKYACTIV technologies that Mazda plans on introducing to its global lineup, a unique start-stop system is one of the most important. Initially Mazda had decided not to bring its idle-stop system to the US as the EPA system didn’t measure a major improvement in efficiency, but ultimately the decision was made to make all of its vehicles idle-free by 2015. But an early test of a SKYACTIV idle-stop-equipped Mazda2 by Automotive News [sub]’s Hans Greimel reveals an interesting characteristic:

a funny thing happened when I paused for a red in Tokyo’s harbor district.

After a few moments of silence, the engine clicked on, as designed, to help keep the air conditioner going. OK, that’s normal. But as the engine jumped to life, so did the steering wheel. To my surprise, I found the engine’s start-up vibrations turning the wheel to-and-fro in my loose grip.

I turned to the Mazda powertrain engineer sitting beside me.

“Didn’t engineers notice that during development?”


“Well, didn’t they try to fix it?”

“Yes, but they decided this amount of feedback was acceptable.”

I’ve driven cars with stop-start engines before, but this was a first. The self-animated steering wheel only happened once during my 40-minute run. And it was more an unexpected annoyance than a safety issue. But I suspect it will take drivers some getting used to.

Greimel says the SKYACTIV Mazda2 1.3 won’t be sold in the US, but the same technology will arrive with the next Mazda3. Because Mazda’s idle-stop system uses detonation rather than an electric motor for re-start, it eliminates a key problem with early stop-start systems: battery wear-down. But apparently Mazda’s detonation-based system isn’t without its downsides. Here’s hoping they work out the kinks before bringing the system to the mass market.

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4 of 36 comments
  • MadHungarian MadHungarian on Aug 15, 2011

    Does this system avoid using the starter motor entirely for restarting, or not? On the Mazda website, the third diagram toward the bottom of the page is captioned "Combustion + Motor Assist" and the graphics suggest the starter motor is operating. If this works so well, why not eliminate the weight of the starter motor and start the engine this way all the time?

    • See 1 previous
    • Robert.Walter Robert.Walter on Aug 16, 2011

      Cylinders are not a perfect seal either ... even if the engine were maintained at the optimal warm temperature for compression-based starting, the cylinder pressure would vent past the rings and be lost over time... I also assume, but am not sure, that there would be additional incremental leakage over the valve seats too...

  • Wmba Wmba on Aug 16, 2011

    The Mazda Global site has had info on this stop-start system for over a year now. It doesn't rely on compression to start, it depends on the engine stopping at the exact right point, so that a squirt of gas and the air left in the cylinder are ignited by a spark and off she goes. Sounds like it might be a bit of a rocky start if it twitches the steering column, though. I wonder how they integrate it, or any stop-start system with an automatic trans, where one has to press the foot brake to use the starter motor. Interesting logic train that will have to be followed to do this automatically. Manual tranny no problem.

  • Ollicat I have a Spyder. The belt will last for many years or 60,000-80,000 miles. Not really a worry.
  • Redapple2 Cadillac and racing. Boy those 2 go together dont they? What a joke. Up there with opening a coffee shop in NYC. EvilGM be clowning. Again.
  • Jbltg Rear bench seat does not match the front buckets. What's up?
  • Theflyersfan The two Louisville truck plants are still operating, but not sure for how much longer. I have a couple of friends who work at a manufacturing company in town that makes cooling systems for the trucks built here. And they are on pins and needles wondering if or when they get the call to not go back to work because there are no trucks being made. That's what drives me up the wall with these strikes. The auto workers still get a minimum amount of pay even while striking, but the massive support staff that builds components, staffs temp workers, runs the logistics, etc, ends up with nothing except the bare hope that the state's crippled unemployment system can help them keep afloat. In a city where shipping (UPS central hub and they almost went on strike on August 1) and heavy manufacturing (GE Appliance Park and the Ford plants) keeps tens of thousands of people employed, plus the support companies, any prolonged shutdown is a total disaster for the city as well. UAW members - you're not getting a 38% raise right away. That just doesn't happen. Start a little lower and end this. And then you can fight the good fight against the corner office staff who make millions for being in meetings all day.
  • Dusterdude The "fire them all" is looking a little less unreasonable the longer the union sticks to the totally ridiculous demands ( or maybe the members should fire theit leadership ! )