Transmission 3rd to 2nd shift shock??

[z80kid]

I've been plugging away at this for some time with no results, no any suggestions are welcome.

 

When accelerating from a stop, the transmission behaves perfectly. Smooth shifting right up through the gears, even if I'm hammering it.

 

Kickdown from fourth to third seems instantaneous and is also smooth.

 

But kickdown from third to second is painful. It seems to take at least a full second - during which the engine revs up a bit causing the transmission to SLAM hard enough to bark the tires when second eventually engages.

 

(Often the upshift following this downshift will also be rough.)

 

Kickdown from second to first is quick and smooth.

 

What I've tried so far:

 

Resistance test on all of the solenoids and sensors through the transmission harness. (Tested good).

Resistance test of the dropping resistor (also good).

Changing ATF and adding Lucas trans treatment.

Added marvel mystery oil two weeks later.

Changed ATF again 2 weeks later and tried Trans-X.

Changing front and rear differential oil.

"Resetting" the TCU by disconnecting battery for 20 minutes and stomping brake several times.

 

If some of the above seems irrelevant and/or stupid, I did it following the advice of others out of desperation. :-\

 

Transmission light is out, and there are no codes.

 

Any suggestions would be greatly appreciated.

 

Thanks

 

Addl info - the vehicle is a 2000 Subaru Forester L

Edited October 26, 2010 by z80kid
Addl info

[SubaruAlliance]

does it shift hard all the time or only when your hammering on it? what if you try to downshift it manually so you can kick it down without having to hammer on it i mean even under normal driving to get it to kick down from 3rd to 2nd you have to really gas it, maybe you can ease it into 2nd, accelerate, and then hit 3rd?

[Suba9792]

you put mmo in your tranny?

[z80kid]

does it shift hard all the time or only when your hammering on it? what if you try to downshift it manually so you can kick it down without having to hammer on it i mean even under normal driving to get it to kick down from 3rd to 2nd you have to really gas it, maybe you can ease it into 2nd, accelerate, and then hit 3rd?

It always slams. I'm usually not "hammering it" when it drops to 2nd. Usually I'm either maintaining my speed on a large hill, or I've slowed way down for a curve and I'm lightly accelerating out of it.

 

The only time it won't slam is if I'm not applying any gas at all when it shifts - like when I brake to a full stop.

 

I've not tried to manually downshift. When I "feel" that it's about to downshift, I'll give it a quick shot of the gas pedal to induce the shifting process and then back off immediately. As soon as the shift is complete, I'll resume the gas again.

 

That smooths it out, but it's not a permanent fix. And I don't feel good about letting family members borrow the car because they'll slam it.

[z80kid]

you put mmo in your tranny?

 

Yep. It can be used as a cleaning agent.

 

In my case, it didn't change anything. I flushed it out before trying the trans-x, because I had also tried Lucas and I didn't want to mix too many additives at once.

 

Ha! Your question just made me check their web site. In the shop we'd used the stuff in our air tools and I'd seen it used to break up sludge in transmissions and crank cases. NEVER seen it used in the gas tank, although apparently that's where it's actually supposed to go.

[nipper]

How about the shifting resistor under the battery? It is there to reduce shift shock. Also check your tranny mount. SUnarus shift hard, but usually it is the up shift not the down shift.

[z80kid]

How about the shifting resistor under the battery? It is there to reduce shift shock. Also check your tranny mount. SUnarus shift hard, but usually it is the up shift not the down shift.

 

I mentioned the dropping resistor in the original post. It tested fine.

 

I'm certain that the tranny mount has had it. But I'm loathe to replace it until I get the shift problem under control. The tranny mount explains the slamming sound, but the barking tires indicates that I'm still shifting way too hard.

 

A new tranny mount will just transfer power to the tires faster and make the shift eveb harder - until the new tranny mount dies under the stress as well.

[z80kid]

I tried "hammering it" tonight and found something interesting.

 

If I'm coasting slow in third, and I give it a little gas to shift to second, I get the slam.

 

BUT, if I floor it and it goes straight to first it's smooth as silk. No slam!

 

I'm convinced there is something significant about the fact that the slam only occurs going down into second.

[OB99W]

If coasting downhill in 3rd, is there engine braking?

[z80kid]

If coasting downhill in 3rd, is there engine braking?

 

Hard to say. There seems to be some, depending on how fast I'm coasting. Seemed like when I was doing 45 and pulled it down to 3rd, it would slow down for a moment, then start coasting again.

 

Tried manually pulling it down into second today as I approached hills. No slam, even if I'm stepping on the gas.

[nipper]

I mentioned the dropping resistor in the original post. It tested fine.

 

I'm certain that the tranny mount has had it. But I'm loathe to replace it until I get the shift problem under control. The tranny mount explains the slamming sound, but the barking tires indicates that I'm still shifting way too hard.

 

A new tranny mount will just transfer power to the tires faster and make the shift eveb harder - until the new tranny mount dies under the stress as well.

 

NO.The tarnny mount can be the cause of the noise and the feeling of the shock. It really is NOT a good thing not to replace something that is known to be broken when it is hampering the diagnostic process.

 

A tranny mount will NOT tranfer power faste, it will keep the driveline straight,and oh, make it stop clunking or reduce it. i know it did mine.

[z80kid]

A tranny mount will NOT tranfer power faste, it will keep the driveline straight,and oh, make it stop clunking or reduce it. i know it did mine.

 

I suppose I could give it a shot, since I'm running out of other options.

 

Here's my reasoning:

 

While the trans mount itself doesn't transfer power per se, it holds the trans in place while the trans applies torque to the wheels.

 

If the mount is broken, the power from the engine will move the trans as far as it can before moving the tires. That power is essentially wasted.

 

My fozzie is applying enough instantaneous power to both move the transmission AND peel the tires. If the transmission is anchored solidly in place, ALL of that power will go to the tires.

 

While I planned to replace the mount, I did not want to expose the new mount to this excessive torque and have it go bad too.

[OB99W]

Lack of engine braking can indicate an internal trans problem. On the other hand, a bad trans mount can allow the driveline to "wind up" and suddenly release, and possibly cause what you're experiencing. I'd change the mount before further analysis.

[nipper]

I suppose I could give it a shot, since I'm running out of other options.

 

Here's my reasoning:

 

While the trans mount itself doesn't transfer power per se, it holds the trans in place while the trans applies torque to the wheels.

 

If the mount is broken, the power from the engine will move the trans as far as it can before moving the tires. That power is essentially wasted.

 

My fozzie is applying enough instantaneous power to both move the transmission AND peel the tires. If the transmission is anchored solidly in place, ALL of that power will go to the tires.

 

While I planned to replace the mount, I did not want to expose the new mount to this excessive torque and have it go bad too.

 

Nice try but the movement is so little that does not apply. It is just enough to make a clank or a thud. It can also stress the engine mounts and flex the coolant lines

[SubaruAlliance]

it's interesting that there is no slam when you manually put it into second, regardless of how much throttle your giving it. that to me would indicate that the kick down side of the tranny is making it shift improperly, and not so much an issue with the tranny itself. seems as though it shifts properly when YOU shift it, but not when the car tells it to shift from your pushing on the throttle and making it kick down.

 

probably wouldn't hurt to double check fluids, wires, and resistors, in my experience, most of the tough problems are caused by something fairly simple, or something easily overlooked.

[OB99W]

There are several possible conditions that can cause excessive shift shock. One of them is inability of the TCU to see the throttle position. However, that and others that are electrical in nature typically make themselves known via TCU trouble codes being triggered. Unfortunately, the TCU can't report on problems that are strictly mechanical.

[nipper]

I need a basic so I can look it up in the FSM, what year and how many miles.

[OB99W]

I need a basic so I can look it up in the FSM, what year and how many miles.

From the first post of this thread, "2000 Subaru Forester L" -- mileage not given as of yet.

[nipper]

From the first post of this thread, "2000 Subaru Forester L" -- mileage not given as of yet.

 

That i need too.

[z80kid]

That i need too.

 

145k

[nipper]

Shock from 3 to 4th

1) Control module

2) Throttle position sensor

3) 2-4 brake duty solenoid

4) ATF temperature sensor

5) Line pressure duty solenoid

6) Control valve

7) 2-4 brake timing solenoid

8) 2-4 brake

9) ATF deterioration

10) Engine performance

11) Low clutch timing solenoid

12) Low clutch

 

Shock occurs when accelerator pedal is released at medium

speeds.

1) Control module

2) Throttle position sensor

3) ATF temperature sensor

4) Line pressure duty solenoid

5) Control valve

6) Lock-up damper

7) Engine performance

8) 2-4 brake duty solenoid

9) 2-4 brake timing solenoid

10) Low clutch timing solenoid

 

Shift characteristics are erroneous.

1) Inhibitor switch

2) Control module

3) Vehicle speed sensor 1 (Front)

4) Vehicle speed sensor 2 (Rear)

5) Throttle position sensor

6) Control valve

7) Ground earth

 

Now lets start with the cheap stuff.

Run a new ground from the transmission to the chasis or battery (hey its cheap)

Next disconnect the battery for ten minutes and take it for a drive.

 

 

[z80kid]

I don't want to seem ungrateful, but I do have the same manual pages in Alldata. While it says nothing about downshift problems, I did look at the possible causes for shock from 2 to 3. It's where I found the procedure for testing the sensors, solenoids, and resistor.

 

I'm not sure why you posted the sections for shock from 3 to 4 and for shock when releasing the accelerator - I'm not having those problems.

 

Ground tests fine - no resistance from the transmission case to the negative pole OR from the ground wire on the solenoid/sensor wiring harness to the negative pole.

 

I did read somewhere (just yesterday) that some aftermarket transmission filters can be a problem, as they are just oil filters that happen to fit and are too restrictive. I've ordered a genuine Subaru filter just in case. And I'm going to go ahead and try the mounts, although that will have to wait until payday (damned things are expensive!)

[z80kid]

Oh yeah - TPS seems fine as well. At least I can view it on the OBD monitor and it seems to respond smoothly to pedal pressure. Not sure how else one would test it, and I'd expect it to affect all shifts - not just 3 to 2.

[nipper]

I don't want to seem ungrateful, but I do have the same manual pages in Alldata. While it says nothing about downshift problems, I did look at the possible causes for shock from 2 to 3. It's where I found the procedure for testing the sensors, solenoids, and resistor.

 

I'm not sure why you posted the sections for shock from 3 to 4 and for shock when releasing the accelerator - I'm not having those problems.

 

Ground tests fine - no resistance from the transmission case to the negative pole OR from the ground wire on the solenoid/sensor wiring harness to the negative pole.

 

I did read somewhere (just yesterday) that some aftermarket transmission filters can be a problem, as they are just oil filters that happen to fit and are too restrictive. I've ordered a genuine Subaru filter just in case. And I'm going to go ahead and try the mounts, although that will have to wait until payday (damned things are expensive!)

 

 

Well good luck, i'll drop out of this thread.

[z80kid]

The filter seems to have made a little difference - not much.

 

I'm going to go ahead and order mounts on payday.

 

Hope you weren't offended nipper. I don't intend to put down anyone's suggestions. Sometimes just chatting with people - even if it's rehashing old territory or seems unrelated - sparks a thought.

 

And you might be right about the mounts. I'll let you know when they arrive.

 

Thanks all