Freewheeling in "D" or "R" at idle
 

I have to hold the brake when transitioning from one direction to another, or from a stop, on an incline, as the car will roll at idle, forward or backward, as if the gear selector were in neutral. Raise the revs a bit and it'll grab and go.

ATF is clean, clear, and full. No measurable drop in fuel economy (this has been going on for awhile). No unusual delay after shifting from R to D or vice-versa. Good bite in all gears, at any speed. I drove the car 150+ miles Friday, fairly hard, Interstate to curvy, hilly 2-lanes, and the tranny performed flawlessly in every other respect, near as I could tell. I've put over 50,000 miles on this car and believe I'd notice any change in behavior.

So this seems a minor issue, but I'd appreciate some opinions as to what's up, and more importantly, if this a foretaste of bad things soon to come. Could it be something as simple as a bad signal from the TPS?

Thanks,
dcb

Re: Freewheeling in "D" or "R" at idle
 

Hi DCB, I recently had a right front axle blow up on my Legacy. I had to have it towed in. When I backed it out into the street and put it in park, it started rolling backwards down the street. The wrecker guy says you don't have park when you have a blown axle. Although this is a little different it seems like it might be in the same ballpark. Take care, BOBB

Re: Freewheeling in "D" or "R" at idle
 

Thanks, Bobb, but it's definitely not an axle; not a slop-in-the-driveline issue.

Not noticeable at cold idle: This morning I backed out of the garage without touching the gas. Engine braking at speed seems okay, if holding a steady 60 MPH with the cruise control on a downhill grade is any indication.

dcb

Re: Freewheeling in "D" or "R" at idle
 

Sounds like a TPS issue to me...

Re: Freewheeling in "D" or "R" at idle
 

Well, I guess it's cool that there's no deluge of oh-man-yer-screwed replies. I've never replaced the TPS in this car so it's probably original. If I decide to get myself a new one for Christmas I'll update.

Thanks,
dcb

Re: Freewheeling in "D" or "R" at idle
 

Rather than wasting a good Christmas gift on it, usually the stock ones can be adjusted/cleaned.

See how-to documents for further info. Not overly technical, just need some brake cleaner, screwdriver, multi-meter and, of course, patience. ;)

Re: Freewheeling in "D" or "R" at idle
 

If all is ok at cold idle, this would surely indicate that the TPS is unlikely to be involved, as the throttle is not moved in order to set idle speed.

Re: Freewheeling in "D" or "R" at idle
 

First, I'm no expert, wish I could tell you what's up :confused:
Second, what happens to the rpms when you are in D and downshift into 3? Do you get engine braking, or neutral?

Re: Freewheeling in "D" or "R" at idle
 

You say, 'raise the revs a bit and it'll grab and go', do you mean from a stop, in D, the revs must be raised before it goes?
Does the same thing happen from a stop if you select gear 1?
Have you recently driven the car with fwd installed?

Re: Freewheeling in "D" or "R" at idle
 

Thanks for the input, everyone.

My thinking (perhaps overly wishful) on the TPS was that the transmission is not getting a proper signal to "go" at operating temp 'til I bump the revs.

I tried cleaning the TPS on my other SVX to no effect. Ultimately, replacing that one cured a gear-hunting, weird-inappropriate-AWD-bias condition.

Have not shifted from "D" to "3," nor tested in FWD. Will do.

It's not just in drive, also reverse. I first really became aware of this when backing into a parking space on a nose-down incline. At idle, if I don't hold the brake the car will roll forward—selector in "R"—as if in neutral. Waiting for a car to pass before making a left recently, incline reversed, in "D," the car wanted to roll backward.

At or above, say, 1000 RPM, all seems good. I drive this car 2-3 times per week at minimum (25+/- mile RT, 2-lane, curvy, rolling terrain) and have noticed no other worrisome behavior.

Transmission was alleged to have been recently rebuilt when I bought the car @104,000 miles. My "proof" of this: An e-mail from the salesman.:D

dcb

Re: Freewheeling in "D" or "R" at idle
 

I'm not suggesting that you test the car in fwd, only asking about downshifting from D to 3, and asking about starting in gear 1 vs. D. Did you recently buy this car?

Re: Freewheeling in "D" or "R" at idle
 

No, I've put fifty-something thousand miles on this car. No tranny work excepting normal fluid changes. Came with a "campaign" external filter (which has been replaced once) and I added an aux. cooler.

I'll drive it tomorrow and check engine braking in 3 and starting in 1 on an incline.

dcb

Re: Freewheeling in "D" or "R" at idle
 

The symptoms appear to indicate that the problem is engine speed related. The TCU relies on a signal from the ECU in this respect, which in turn receives signals from engine speed sensors. The crank angle sensor signal would be the most likely culprit.

These sensors deliver a series of pulses when magnetically activated. It is possible that at low RPM there is insufficient signal being delivered, but this is not a likely scenario. However you have an intermittent fault, and therefore you must suspect the unlikely.

Run an engine diagnostic check as per the how too information. You will be looking for code 11 or maybe 13. Unfortunately as the fault is intermittent this check can not be absolutely relied upon, but will be the first line of approach.

Re: Freewheeling in "D" or "R" at idle
 

NeedForSpeed, sorry, I misunderstood. No, I have never driven this car in FWD mode.

More info:
—Pronounced engine braking at highway speed, selector in "3."

—Aggressive throttle-forced downshift and acceleration, overtaking slower traffic, 55-75 MPH.

Next: codes. Thanks again to all.

dcb

Re: Freewheeling in "D" or "R" at idle
 

Does car take off in gear 1, unlike in D? You have codes that you haven't checked?? Read Trevor's advice, with two cars, you can swap the easy parts to diagnose/confirm.