Transmission "freewheels" at v. low speed

[DaveCC]

1989 Toyota Camry 2.0L 3S-FE, 2-wd, auto trans (A140E). 120K miles, about 35K on this transmission.

When driving below 10 mph, using on-again-off-again on the accelerator pedal (ie, as traffic pulls away from a stop light, and everybody's brake lights are going on and off), if I accelerate a little then let off the gas, then press it on again, the car doesn't respond immediately, but the transmission "freewheels" a little (a half second?) and then catches.

Above 10 mph this does not occur.

This is not a "slipping" issue; something is definitely disengaged briefly.

Trans fluid it full (but not overfull).

This has always happened since I've owned the car (about 7 months).

Is this an imminent failure mode? Or a "they all do this" issue?

I want to emphasize that this is not a slipping band or clutch pack. If I accelerate from a stop "with gusto", all the shifts are normal, crisp, with no flaring. If I accelerate from a stop, it does not occur. Once above 10 mph it no longer happens even if I get "on and off" the accelerator. It's just in that 5-10 mph window and on-and-off with the gas.

Ideas?

Thanks,
Dave

[kesando]

My Car does this too. It only happens when in traffic or accelerating from a red light that just turned green (car in motion). I have made it a habbit to feather the throttle in these situations.

[DaveCC]

Originally Posted by kesando

My Car does this too. It only happens when in traffic or accelerating from a red light that just turned green (car in motion). I have made it a habbit to feather the throttle in these situations.

What Model & Year is this car?

I, too, have learned to press *very* lightly on the gas in this 5-10 mph speed. It's a pain.

Dave

[kesando]

its a 1990 Camry 4cyl with 114k miles.

[DaveCC]

I wonder, could this be a valve body problem? Stuck valve? Broke spring?

Dave

[Doctor J]

You should make 2 tests:
accelerate with selector in low
if it improves you have problem in forward clutch [leaking apply piston seal]
or do the stall test
in D position and check the RPM
(note this test may make the problem worse)
I still thinking that it can be engine related aka flat spot due to the TP sensor out of adjustment

[DaveCC]

accelerate with selector in low. if it improves you have problem in forward clutch [leaking apply piston seal]

Wouldn't this problem show up as slipping shifts (flaring) during during normal acceleration? The symptom *never* appears during normal acceleration from stop if I don't pause during 5-10 mph.

or do the stall test in D position and check the RPM (note this test may make the problem worse)

How will know if this is the problem? Will the RPM will be too high? If this turns out to be true, what is the cause?

I still thinking that it can be engine related aka flat spot due to the TP sensor out of adjustment

Wouldn't this problem show up during normal acceleration? (BTW, I replaced the TPS due to idle speed problems -- no change in this "freewheeling" symptom).

The symptom is not a hesitation in engine power. The engine definitely revs and there's no "go" until the transmission goes "bang" (like popping a manual trans' clutch) and "away we go"! The "bang" can be gentle or harsh, and this is where anticipation and gentle application of the right foot are important.

Thanks a lot for your comments. Discussion is the path to solution. :-)
Dave

[Doctor J]

Normal stall speed is about 2200 rpm taking to consideration older engine; If stall rpms are 2800 the tranny is slipping.If it does so in all ranges the problem can be related to the low line pressure
Dirty tranny filter can cause low pump output at low rpm and low line pressure.
The engine will not "flare" unless clutches are burned badly.
Drop the pan inspect the screen and check the throttle valve adjustment.

[kesando]

Originally Posted by Doctor J

Normal stall speed is about 2200 rpm taking to consideration older engine; If stall rpms are 2800 the tranny is slipping.If it does so in all ranges the problem can be related to the low line pressure
Dirty tranny filter can cause low pump output at low rpm and low line pressure.
The engine will not "flare" unless clutches are burned badly.
Drop the pan inspect the screen and check the throttle valve adjustment.

can this freewheeling worsen to the point of tranny failure in the long run? Years/months?

[Doctor J]

Our customer's 81 cressida lasted with this defect about 7 years and tranny never failed; however thae camry may be different

[DaveCC]

Originally Posted by Doctor J

Our customer's 81 cressida lasted with this defect about 7 years and tranny never failed; however thae camry may be different

Was the cause ever known? Defective valve body? Sticky shift solenoid? Bug in the trans electronic unit?

Thanks,
Dave

[Doctor J]

The tranny have been never disassembled; that year Cressidas had no electronic t/m control and no locking torque converters. Most likely the problem for that car related to the pressure loss due to old rubber seals inside tranny.

[sleep_deprived129]

Originally Posted by DaveCC

1989 Toyota Camry 2.0L 3S-FE, 2-wd, auto trans (A140E). 120K miles, about 35K on this transmission.

When driving below 10 mph, using on-again-off-again on the accelerator pedal (ie, as traffic pulls away from a stop light, and everybody's brake lights are going on and off), if I accelerate a little then let off the gas, then press it on again, the car doesn't respond immediately, but the transmission "freewheels" a little (a half second?) and then catches.

Above 10 mph this does not occur.

This is not a "slipping" issue; something is definitely disengaged briefly.

Trans fluid it full (but not overfull).

This has always happened since I've owned the car (about 7 months).

Is this an imminent failure mode? Or a "they all do this" issue?

I want to emphasize that this is not a slipping band or clutch pack. If I accelerate from a stop "with gusto", all the shifts are normal, crisp, with no flaring. If I accelerate from a stop, it does not occur. Once above 10 mph it no longer happens even if I get "on and off" the accelerator. It's just in that 5-10 mph window and on-and-off with the gas.

Ideas?

Thanks,
Dave

I haven't read through this whole thing so I apologize if this has already been said but I would check your filter, a full tranny does no good if it doesn't flow freely!

[DaveCC]

Originally Posted by Doctor J

The tranny have been never disassembled; that year Cressidas had no electronic t/m control and no locking torque converters. Most likely the problem for that car related to the pressure loss due to old rubber seals inside tranny.

In my case the car has done this since I got it with 58K on a dealer-installed rebuilt trans. So, old seals? I think it's got to be (in my case) something else.

And loss of pressure: wouldn't this make the symptom full-time? (ie, not grab), or at lease recur if engine speed drops (foot off of gas)?

Thanks.

[fredk]

youve got a small pressure leak