TRAC traction. Does it affect mileage??

Discussion in 'General Motoring' started by TSMANGOD, Jan 6, 2005.


    TSMANGOD Guest

    Howdy. I've asked this of several people who own Saturns, and nobody can tell
    me the advantage/disadvantage of having the Trac traction switched on versus
    turning it off. I usually turn it off, because the light annoys me, but if I
    were on slippery roads, I'd use it.
    But does it have any effect at all on the mileage? The traction advantage
    seems so minimal when you know what you're doing behind the wheel. Snow isn't
    the problem it's made out to be, but this Traction thing looks like it's mostly
    a useless bell/whistle, like the switch that makes it shift differently. I've
    never noticed a difference there, either.
    TSMANGOD, Jan 6, 2005

    marx404 Guest

    Simply put, traction control prevents wheel slippage by applying brakes and
    reducing power to the specific slipping wheel so that that all wheels keep
    good traction on the road. I have never heard of TC affecting mileage at
    all. TC is great if you want more traction on rainy, snowy, or any road
    conditions. By improving traction, you basically improve your handling too.

    What TC does affect is your speed. Naturally, if TC needs to slow down a
    misbehaving wheel, ie: you are street racing and want your wheels to spin,
    then you would want to turn TC off. Otherwise, TTC does work and is intended
    to be completely invisible to the driver as it does it's job.

    marx404, Jan 6, 2005

    Oppie Guest

    Howdy back at you -
    afik the traction control on my '01 lw300 does not affect the engine or
    shifting under normal circumstances. What it does do when it detects a wheel
    slip (on acceleration) is to apply the brake to the slipping wheel. This
    attempts to divert power to the wheel that still has traction and to regain
    traction on the slipping wheel. If this is not successful, the engine power
    is cut back until the wheel slip is eliminated. The dashboard 'low traction'
    indicator will come on for either of these conditions. There is no need to
    let up on the accelerator since this is automatic.

    Wheel slip is detected by sensing wheel RPM on all wheels and comparing
    results. Wheel rpm is affected by the wheel radius and radius is a function
    of tire pressure. What is important to keep in mind is that you should
    always use identical wheels and tires, keep the inflation to spec and rotate
    the tires on schedule to keep the radius on all tires identical. If you have
    a tire that is starting to run flat, then it is a good idea to switch off
    the traction control until your fix the flat. (of course, never drive on a
    flat tire unless you want to buy a new tire and wheel).

    Where I see the traction control coming on mostly is in wet weather when the
    car starts to hydroplane. Also on heavy acceleration for passing, I get much
    better stability with the traction control enabled. Compared to the minivan
    I used to drive, the lw300 is a muscle car and the ABS/TRAC systems are well

    Keep the bugs off the bumper and the shiny side up y'all.
    Oppie, Jan 6, 2005

    GCC Guest

    No need to let off the accelerator? So I can just keep going as usual and
    will compensate for me? Cool...

    Usually I use the LOW TRAC as an indicator I am on an ice patch and let off
    the gas, then accelerate slowly from a stopped postion.

    I've got a Blue '03 Ion QC w/ body kit.
    GCC, Jan 7, 2005

    Oppie Guest

    I always recommend that you read the owner's manual (took me 3 times through
    to get all the significant details). There is a lot of information there
    about the correct operation and care of your vehicle. Take some of it with a
    grain of salt and others as the gospel truth. (you decide with the filter of

    The automatic compensation of throttle in a low traction event may vary from
    vehicle to vehicle. The L300 is a drive by wire and the computer actually
    controls the throttle. The accelerator pedal talks to the computer and has
    no direct mechanical connection to the throttle. (a bit strange at times).

    In a low traction event, the L300 backs off the throttle. On non-drive by
    wire cars, the engine power is reduced by retarding the spark timing. This
    is not as effective as the computer controlled throttle. It does work but in
    either case, for a prolonged loss of traction, it is best to lift your foot
    slightly off of the pedal.

    Oppie, Jan 7, 2005

    Kirk Kohnen Guest

    I'm not sure how the non-drive-by-wire, but otherwise computer controlled
    engines throttle back. Retarding timing would be one way, reducing or
    cutting off injectors would be another way.

    Anyone out there in Saturn land *KNOW* how the computer throttles back the
    engine in this case?
    Kirk Kohnen, Jan 8, 2005

    Oppie Guest

    We had a couple of inches of good packing snow the other day. On the way
    home from work, on the parkway which had not been plowed or salted yet, the
    surface was slushy. The lw300 was handling just wonderfully even with the
    uneven and slick surface. At about 40mph, I turned off the trac switch. The
    handling suddenly became much more unstable and I had to very carefully
    compensate for every furrow and puddle. Switched the traction control back
    on for the remainder of the trip home. Even changing lanes from a well
    traveled surface to an un-traveled one was nice and smooth.
    Got to love technology when it works properly.
    Oppie, Jan 12, 2005

    Marc H.Popek Guest

    Don't know about the gas mileage aspect. I would suspect it does nothing but
    "watch" the relative wheel motion. this uses very little power.

    I had similar questions about the feature, as well. It's sorta newly
    emerging Older technology for the masses and we are not used to the feature
    or the display.

    The feature TRAC is great! you hardly notice it, EXCEPT it removes all
    slipping and sliding. Provides very crisp handling in tight turns, wet
    roads, etc.

    The advise I received was to go out and try to slip the wheels without the
    TRAC and then put it on. This way you can feel the effect in a controlled
    off-road situation and anticipate what it does in traffic. ...In the mean
    time... leave it on!
    Marc H.Popek, Jan 17, 2005

    Oppie Guest

    Short answer is that Traction Control (if all is well) does not affect gas
    If you have one tire, especially a drive wheel, that is low on air, it might
    fool the system into dragging a brake. Not entirely sure if this scenerio is
    correct but could conceivably cause a loss in mileage. Bottom line is to
    check tire inflation regularly and rotate tires on schedule for best
    Oppie, Jan 17, 2005
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