In Drive, on level surface, it goes merrily down the street at 10 mph w/o foot on accelerator. Is this normal?
pretty much any vehicle with automatic transmission will tend to creep forward in drive, with your foot off the accelerator pedal, even gaining some speed
Is this vehicle new to you?
Do you have a specific concern?
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Thanks for info. You’d think years of car-owning, I might have noticed this before, but I never did. It was pretty amazing to go the whole block down my alley from garage to street, just sitting there.
When in neutral, what is the idle RPM? (assuming you have a tachometer). It may be set too high.
Modern automatics should not creep at 10mph at idle. I suspect your idle is too high.
In decades past, 10mph creep was common for an automatic. Torque converters weren’t as efficient back then. But in the quest for better CAFE ratings, manufacturers have evolved torque converters to where they pretty much totally prevent any load on the engine while stopped, by allowing almost zero energy to be transmitted to the tranny input shaft.
The answer to Bill’s question, what’s the idle in neutral when at operating temperature, could yield valuable clues.
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It’s at 1. Does that sound o.k.?
Thx
you mean 1000 RPM? when the car is warmed up?
that is high, usual is 600-800 RPM. What does your users manual say?
This is really interesting. I started the car, put in N, the tachometer needle is at 1.
This is a 2010 with K70 miles but it’s been fine – done all the regular maintenance as required and no problems.
Thx
What is the RPM when it is warmed up?
Has it had this creeping problem before?
Hmmm. Let me go back and look. Does this pic help? I’ve just started the car when took it. 60 degrees outside temp.
temp gauge is at “C”. motor is cold. 1100rpm is expected in that situation. try neutral test after 10 min drive and take another pic
Thanks. Will be later on today or maybe tomorrow but will do it and take new pic. I appreciate all the suggestions.
Jean
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Here’s pic after 20 minutes or so of driving. Appreciate this forum and the help.
That’s about 800 RPM’s
Looks normal.
Tester
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Thanks. Someone I know has an SUV, forget which make, but it goes merrily along at 5 mph (whereas mine goes at 10 mph) and it even goes uphill and downhill at the same speed.
So important to keep one’s foot on the brake. Or bad things could happen?
Perhaps that “someone” would be willing to write to us on the forum?
Up and down hills at the same 5 mph, doubtful.
No just counting on me to share. I do appreciate the forum replies.
I was in the other car as passenger. We were simply interested to observe that it continued to travel on its own, either on the flat or up/down a gentle city grade (didn’t look at speedometer, on the up/down grade). Should have said “grade” not “hill”
We thought it was interesting that another car did it, too.
I posted the two pics of the tachometer from my car, as requested, and we are concluding is that it is simply a function of that car.
We thank you all for taking the time to reply
Jean
Just for informational purposes, the way the powertrain works is that the engine output is connected to the transmission input by a “fluid coupling” device called a Torque Converter (TC). It sort of resembles a bagel split I half and hollowed out, with vanes inside each half and fluid inside. When the car is held at a stop sign, and the engine is at its warm temperature and idling, most of the energy from the engine output is absorbed by the fluid and dissipated as heat through the transmission cooling system. When the engine RPMs get higher, the energy transmitted to the fluid becomes too high to be fully dissipated and the fluid begins to drag the tranny input shaft along with the engine output shaft. That pulls the car along, until at a high enough speed a clutch inside the device locks the halves of the torque converter together and the engine becomes hard-connected to the transmission.
In short, the vanes in the front of the TC drag the fluid along and that drags the back half of the TC along. At a certain speed, the two are locked together. At idle, the fluid doesn’t generate enough turbulence to overcome the vehicle’s powertrain and rolling resistance* and drag the car along. The small amount of turbulence generated is dissipated as heat energy.
*For the purposes of this summary, “rolling resistance” includes all resistances including tires, powertrain friction, fluid resistances, vehicle weight, etc.