Down shifting

[juicegonzalez93]

I havr an 03 A4 1.8t AUTO, gears shift perfectly fine 1-5 but when it down shift from 2-1 it has a jerk to it. . But after driving for a while it seems to be less noticeable. . Does anyone know what it could be or have experienced this problem?

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[diagnosticator]

That is not a problem. There is a wider ratio change from 1>2 and 2>1 than the ratio spread in the other gears, so there is a bump when downshifting to 1st before stopping in tip mode. The trans does not normally downshift to 1st before stopping in D or S modes.

When using tip mode, there is no need to downshift to 1st before stopping. Downshifts from 5th to 2nd if not stopping and upshift from 2nd as you accelerate. Downshift to 1st only after stopping.

When the trans is in tip mode and less in S or D, the torque converter clutch is "closed" or locked up practically all of the time. When in 1st>2nd the TCC only locks up after shifting to 2nd and unlocks after downshifting to 1st.

[juicegonzalez93]

That is not a problem. There is a wider ratio change from 1>2 and 2>1 than the ratio spread in the other gears, so there is a bump when downshifting to 1st before stopping in tip mode. The trans does not normally downshift to 1st before stopping in D or S modes.

When using tip mode, there is no need to downshift to 1st before stopping. Downshifts from 5th to 2nd if not stopping and upshift from 2nd as you accelerate. Downshift to 1st only after stopping.

When the trans is in tip mode and less in S or D, the torque converter clutch is "closed" or locked up practically all of the time. When in 1st>2nd the TCC only locks up after shifting to 2nd and unlocks after downshifting to 1st.

Its rareeeee when i use the tip mode, when this happens is on D and it doesn't really do it on S . . But i believe its what you say it is and glad or hope its nothing bad at all.

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[diagnosticator]

Its rareeeee when i use the tip mode, when this happens is on D and it doesn't really do it on S . . But i believe its what you say it is and glad or hope its nothing bad at all.

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The trans should not be downshifting into 1st in D or S mode, before the car stops rolling. If it is, it will cause the bump you described. I recommend changing the ATF fluid. Use Pentosin ATF-1 100 percent synthetic fluid. ATF-1 is a ZF approved fluid and is on the ZF approved fluids listing. The car must be level front/rear and side to side. Then drian the old fluid from the pan by removing the drain port plug. Next remove the trans pan from the trans and replace the fluid filter. With the trans pan off, clean out the trans pan then reassemble. Refill the trans with new ATF, it will take about 7 or 8 liters. Pump fluid into the trans until fluid starts to overflow/drip out of the fill port. Next, start the engine then continue adding fluid to the trans until fluid starts to drip overflow again. Remove the filing tube, and reinstall the fill port plug lightly tight. Next, with VCDS with the transmission controller open, monitor the fluid temperature. While the fluid is warming up, shift the trans from Park > Neutral > Drive > S holding each gear position for 10 seconds, then shift back from S > D > N > P. If the fluid temperature is at least 35 degrees C, but not more than 40 degrees C, remove the ill port plug and add more fluid to the trans until dripping overflow begins, then replace and tighten the fill port plug. The fluid temperature must not exceed 40 degrees C before dripping overflow occurs and the fill port plug is reinstalled and tightened. Turn the engine off, Done.

The trans fluid level is correct only when dripping overflow occurs from the fluid fill port and the trans fluid temperature is between 35 and 40 degrees C.

After changing the trans fluid and filter, use VCDS to look at Transmission Control Unit measuring block values. Most of the values will have a normal range shown for each. There is a test driving routine to follow while logging certain measuring blocks, after the test drive, use the graphing application in VCDS and graph the logged operating data. Any out of specification values and or fault codes needs to be troubleshot and fixed.

The purpose of the fluid and filter change and test drive data logging, is to identify any out of specification values in order to fix the cause of the trans downshifting into 1st gear prematurely, before the car stops rolling when stopping, that causes the bump into 1st gear.

I can email you the Audi 01V (ZF 5HP19FLA) troubleshooting manual if you are interested in a DIY.

[juicegonzalez93]

When it does that jerk/bump is right between 40-35mph, around 1500rpms right when im braking or let go of gas and it starts reducing speed. And that would help a lot if you wouldn't mind doing that. . I appreciate your help

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[walky_talky20]

I'm pretty sure my TIP always downshifted exactly at 39mph. Every time. It's just a programming thing. Now if it's slamming into gear, you've got a problem. But if it's just a normal, noticeable shift, it's not a problem. "It's a feature".

If you don't like how it's shifting, you can always 5MT swap that pig like it's your job.

[juicegonzalez93]

I'm pretty sure my TIP always downshifted exactly at 39mph. Every time. It's just a programming thing. Now if it's slamming into gear, you've got a problem. But if it's just a normal, noticeable shift, it's not a problem. "It's a feature".

If you don't like how it's shifting, you can always 5MT swap that pig like it's your job.

I would say its noticeable, i feel you can hear it as well , like a small thump. . There's times that i don't feel it as much. I'll probably get it checked out though.

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[diagnosticator]

I'm pretty sure my TIP always downshifted exactly at 39mph. Every time. It's just a programming thing. Now if it's slamming into gear, you've got a problem. But if it's just a normal, noticeable shift, it's not a problem. "It's a feature".

If you don't like how it's shifting, you can always 5MT swap that pig like it's your job.

Downshifts ~ 39 mph, sure, but not from 2nd to 1st. Do you know what the engine RPM must be as the trans shifts from 2nd to 1st at that speed? At 39 mph in 1st gear, engine speed is about 7,180 RPM. The TCU wont even allow a downshift that results in the engine exceeding redline RPM. That requires the engine accelerate from maybe ~4500 to 7180 RPM almost instantly, and that will definitely cause a bump into 1st, Also, not everyone wants a manual trans, something often overlooked here. Besides I don't think a manual trans swap is practical advise since it does not really addresses tip trans shifting complaints.

[diagnosticator]

When it does that jerk/bump is right between 40-35mph, around 1500rpms right when im braking or let go of gas and it starts reducing speed. And that would help a lot if you wouldn't mind doing that. . I appreciate your help

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I can send it as an email attachment. Please PM me your email address.

Problems like this are often a sticky shift solenoid valve or a sticky valve body spool valve. Fairly easy to fix. Fresh fluid alone might eliminate the problem.