Shock (Jump) When Shifting From N To D

[ehabmarco]

i need help for an intermittent problem which could badly damage the drivetrain

I feel a sudden severe shock (jump) when I shift from N to D

When I start the engine in the morning and before engaging the transmission, I hear a very loud sound of oil flow like Whistling as if the oil is stuck somewhere

This sound goes away after about 1 or 2 minutes

If I hear this sound when starting the engine, I know that certainly the shock (jump) from N to D will happen, if this sound don't come still the jump might happen but not all the time

The shock is felt only when the car is stopped and I shift from N to D

However sometimes the shifting from N to D is smooth (providing that this sound when starting the engine did not occur)

The transmission is shifting very smoothly between all gears at all times

No codes for transmission when checking in normal or test modes

Thanks for your help

[steve2006]

When did you last change the transmission fluid? Are you sure it is Toyota Type IV in there? Have you checked the fluid level by the recommended method when hot?

The Aisin A340 transmission has a shift shock system which means it should first shift into 2nd when going from N to D and then drop into 1st.

If the normal shifts are OK it would suggest the solenoids are working normally but it could be a line pressure problem.

[landar]

Interesting info, Steve. Here I was thinking of bad mounts...engine or transmission, driveshaft joint or differential.

[ehabmarco]

Thanks Steve

I was doubting this problem might be caused by a stuck solenoid valve or transmission fluid as you said

I think I shoud start by changing the transmission fluid this week and I will post the result, I hope this will clear the problem

Last time I changed the transmission fluid was 2 years back and I am not sure about its type

I am quite sure this "jump" is not resulting from a bad mount or joints as I would have felt it each time which is not the case

Is there any filter I should change in the transmission while changing the fluid?

[steve2006]

Yes there is a transmission fliter accessed by removing the sump pan.

http://www.lexls.com/tutorials/transmission/transchange.html

[ehabmarco]

Bad news

While changing the transmission oil my mechanic noticed many metallic parts and said that transmission is in a very bad condition and needs to be changed

[steve2006]

Not a good result then, if you decide to get a transmission from a breakers make sure you also get the torque convertor with it and don't allow it to come off the shaft in transit or it will need setting up again.

[ehabmarco]

I returned to the mechanic today to schedule changing the transmission, when I asked him again about the particles he found he told me it was aluminum parts catched by the filter

I still doubt the problem might be electrical

When I am in N position and raise the rpm and wait for rpm to return to idle, and then shift to D, I can feel this jump, if I repeat this operation without also moving the car, this silly jump disappears

So playing with rpm few times and returning to idle while the car is stopped make this jump come or disappear

This is driving me crazy....

[ehabmarco]

Update: Cleaned the solenoids valve, no improvements

In the repair manual is says if there is a harsh engagement between N to D first thing to check is the TPS then the solenoid valve # 4, I started wrong by the solenoid I will try now to adjust TPS and see what is gives

[ehabmarco]

Tps checked it was ok finally ransmission changed and problem is resolved

[Micah.Berry]

While it's unfortunate that you ended up having to replace the transmission, I'm glad the problem is resolved for you.

Micah