Acceleration too sensitive issue

Messages
233
Location
Toronto
Hi everyone,

Bought a used low mileage mazda cx 7 2011 with the 2.5L automatic 2wd (non-turbo).

Everything is fine but acceleration is extremely sensitive and I'm pretty sure this is not normal.

What I mean by extremely sensitive is that when you press the accelerator pedal about 5% of the way, it's like the throttle has opened more than 50%.

If I press the pedal delicately I can get a smoother acceleration without the jump forward but then it's really hard to control to get a faster acceleration going.

So I can't really get a steady "middle" acceleration so to speak. Either slow or fast.

The vehicle otherwise drives and shifts smoothly in all gears without any issues.

I did some research online and it seems to come down to three things:

1) throttle position sensor
2) accelerator pedal
3) MAF sensor

Apparently there is also a case (I have not tried it yet) where if the battery is disconnected and the computer is reset, the problem goes away for a day and then returns.

The design is a drive-by-wire.

I was thinking of doing basic maintenance first, changing the spark plugs and cleaning the MAF sensor. Unrelated but may as well change the PCV valve as well.

Does anyone know where the likely culprit would be here?

Also would a basic scanner give like signal voltage for the throttle sensor or do I have to measure that manually?


Thanks
 

tookien

Thread starter
Messages
233
Location
Toronto
I will try relearn process, see if that helps and report back.

disconnect battery, wait reconnect
ignition in "on" position for 1 minute (engine off)
ignition in "off" position for 1 minute
start the engine and let idle for 15 minutes
 
Messages
3,195
Location
Western S.C.
... when you press the accelerator pedal about 5% of the way, it's like the throttle has opened more than 50%.
... Does anyone know where the likely culprit would be here?
I can't tell whether this applies in your example, but manufacturers often deliberately program throttle response to do that, in order to make vehicles seem more powerful than they actually are. Imagine trying to drive it on ice! A couple of months ago, I drove a friend's 2012 Forester, which was very annoying that way.
 

JHZR2

Staff member
Messages
46,293
Location
New Jersey
Ive expereinced that with most toyotas Ive driven. Thought it was a "feature" to make people think their cars are fast.
 

tookien

Thread starter
Messages
233
Location
Toronto
I can't tell whether this applies in your example, but manufacturers often deliberately program throttle response to do that, in order to make vehicles seem more powerful than they actually are. Imagine trying to drive it on ice! A couple of months ago, I drove a friend's 2012 Forester, which was very annoying that way.

Initially I thought so as well when I was test driving the vehicle, but now it just doesn't seem right.

Someone can get into an accident and like you said, could make it difficult to drive on snow or ice.

The reason why I think it's wrong is that you can't get a steady acceleration without it being too slow or too fast no matter how delicate you are, which is really annoying.

Once you press the pedal just a little more it yanks the car forward like the throttle has just opened up +50% more.

However once you do get going from the slower start it's no longer an issue and the pressing throttle more will not yank the vehicle.
 

tookien

Thread starter
Messages
233
Location
Toronto
Reset the battery.

When I step on the throttle now during the relearn process the idle does seem quirky, when raising RPM's will then go down and up then will stabilize to idle. When I look at the TP %, it stable at around 13, raising RPM goes up smoothly % interval, but then letting go goes to 11-12. Not sure if that's normal.
 
Messages
59
Location
The web
See if it has an aftermarket pedal enhancer installed. You can get them for just about any car from a multitude of aftermarket tuning companies. All they do is plug in between the pedal and the harness, and you can adjust them to make the pedal almost dead numb to being little more than a full throttle on-off switch. Some people think they're cheesy and others wouldn't drive without them. I've tried one and it can definitely make an otherwise numb car feel quick perky. Just something to check for.
 
Messages
1,767
Location
Richmond, VA area
Funny, what you are describing is what many with other makes/models want - less delay in the throttle. Are you sure there isn't a pedal tuner box under there hiding? That's what it sounds like.
 
Messages
2,346
Location
Middle of Iowa
key on, engine off...watch the throttle position sensor feedback for linearity as you push the pedal. It is normal to not have it drop all the way back to zero, and also normal if you don't hit exactly 100%. What you are looking for is the relationship between your foot and the change in %.
 
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