Jump to content

The RennTech.org community is Member supported!  Please consider an ANNUAL donation to help keep this site operating.
Click here to Donate

Welcome to RennTech.org Community, Guest

There are many great features available to you once you register at RennTech.org
You are free to view posts here, but you must log in to reply to existing posts, or to start your own new topic. Like most online communities, there are costs involved to maintain a site like this - so we encourage our members to donate. All donations go to the costs operating and maintaining this site. We prefer that guests take part in our community and we offer a lot in return to those willing to join our corner of the Porsche world. This site is 99 percent member supported (less than 1 percent comes from advertising) - so please consider an annual donation to keep this site running.

Here are some of the features available - once you register at RennTech.org

  • View Classified Ads
  • DIY Tutorials
  • Porsche TSB Listings (limited)
  • VIN Decoder
  • Special Offers
  • OBD II P-Codes
  • Paint Codes
  • Registry
  • Videos System
  • View Reviews
  • and get rid of this welcome message

It takes just a few minutes to register, and it's FREE

Contributing Members also get these additional benefits:
(you become a Contributing Member by donating money to the operation of this site)

  • No ads - advertisements are removed
  • Access the Contributors Only Forum
  • Contributing Members Only Downloads
  • Send attachments with PMs
  • All image/file storage limits are substantially increased for all Contributing Members
  • Option Codes Lookup
  • VIN Option Lookups (limited)
Ordonezp

Tiptronic Weird Shifting

Recommended Posts

Hi everyone! I’m the proud new owner of a ‘99 Boxster 2.5L. 

 

Recently, I noticed that when my transmission automatically shifts from second to third gear, it’ll jerk very slightly, as if the transmission is stuck for the briefest moment in second gear right before it shifts.

 

More noticeably, when I’m driving to slow down and breaking, as the transmission begins shifting from fourth to third and second, there is some jerking again—the sort of jerking you get when a transmission shifts into a slower gear and the car slows down suddenly because of the lower gear. 

 

So when I’m slowing down, I will be going at a given speed, the car will downshift a gear, I will feel that sudden slow down, the car will run at a lower speed, downshift again, and I’ll feel that sudden slowdown again. This keeps happening until the car reaches second gear, of course. 

 

Because of this, I recently had the transmission fluid changed. My mechanic showed me that the old transmission fluid was black and smelled like smoke, but that he hadn’t found any metal shavings so he thought the transmission was probably still okay. He told me to check in after a couple hundred miles to see if the transmission adjusts and drives better.

 

It’s been a hundred miles, and I’m still seeing this behavior—should I be worried, or is this common in tiptronics? I’m hoping that best case scenario, the car’s sensors are miscalibrated and the trans is downshifting at the wrong times (thus the gap between the speed it’s going at and the slowing down effect of a lower gear). Worst case would be having to buy a new transmission. 

 

Please help! Would appreciate some advice or expertise. 

Edited by Ordonezp

Share this post


Link to post
Share on other sites
    You can remove these ads by becoming a Contributing Member.

It is not common behavior.  You need to recognize that when you changed your old fluid, you only got about 35-40% of it out, the lion’s share is still inside the converter which does not gravity drain.  Unfortunately, Porsche instructions are to change the Tip fluid at 90K miles, which is WAY to long, we typically service customer’s Tips around 40-50K miles.  When we see one with fluid as bad as yours, we typically drain it, change the filter, and then do three fill, run, and drain again cycles to try and flush out as much of the old fluid as possible.  And before you ask, no, there is no way to pressure flush this trans like many other brands can easily be done.  

 

Good luck.

Share this post


Link to post
Share on other sites

“ when I’m slowing down, I will be going at a given speed, the car will downshift a gear, I will feel that sudden slow down, the car will run at a lower speed, downshift again, and I’ll feel that sudden slowdown again. This keeps happening until the car reaches second gear, of course. “

 

Mine does the same, you feel the down shift and then the deceleration braking, I have a 97 2.5 if the trans slips and them jams into gear that is not normal, JFP is right about changing the fluid a friend of mine suggested an additive that their shop puts in Mercedes that works well on the sticky selenoids when the hard shifting happens, but I don’t have the name handy, will check tomorrow and post back!

Share this post


Link to post
Share on other sites

Did you have the codes read? If you have durametric it will read the transmission codes if there are any. These won’t result in a CEL on the display but could still be stored. I would check that to see if that gives you any ideas. Could be a solenoid issue or one of the sensors on the valve body.  Sometimes clogs on a solenoid or something as simple as a bad o-ring on the valve body can cause similar behavior. I would also ask if there was any fiber residue in the retrieved ATF which could indicate wear in the fiber discs inside the trans. Did he also change the trans filter?

Share this post


Link to post
Share on other sites

As you are no doubt aware, there is a precise procedure for refilling the transmission to ensure the correct fill level.

 

Your mechanic presumably knows that?

 

If in doubt, it may be a good idea for you yourself to ensure that the transmission has been filled to that correct level; with the fluid at a temperature of between 35C and 40C.

 

 

Share this post


Link to post
Share on other sites

Hi everyone, thanks for your replies! I touched base with my mechanic, and he said that because it doesn't seem like my transmission has ever been serviced (going on 122K miles), that he thought it was better to replace the fluid gradually as to avoid slipping or damaging the transmissions. He told me to come back after 1000 miles to replace the fluid again. I think the transmission fluid has been filled to the right level--I trust that my mechanic knows what he's doing. For now, the transmission is okay, just not shifting as smoothly as I would like. Definitely better after the original transmission fluid change than before.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Similar Content

    • By Mike Blaszczak
      Hi!
      I have a 1999 C4 coupe with a manual transmission. Earlier in the spring, I had the transmission repaired -- 2nd gear replaced and the pinion bearing replaced, too.
      Since then, I installed a short-shift kit myself.
      Today, I noticed that the back-up lights aren't illuminating. All the gears engage fine, including reverse, so I don't think there's an adjustment problem. I don't know if the lights were working or not before my short-shift installation.
      What are the likely causes for the lights not working? Switch wasn't reconnected after tranny work, or the switch is bad, I guess. But could my short-shift installation be causing the problem?
      Thanks!
       
    • By Amber Wells
      I have a 97 tiptronic non turbo boxster. I blew my front seal so I need to rebuild my tranny. I just need to know what the parts numbers are for the bushing and seal.... I cant seem to find em and want to make sure I order the right parts.
       
      I heard you can actually order a larger bearing and seal and then machine out the tranny where it goes into and in turn avoid this sort of issue for much longer.. if that helps identify what im needing here im sorry im sort of lacking in the lingo im still learning and will update with a better description once i can go over it again with the boyfriend.
    • By Ronnie38
      My 2001 C4 Automatic had what appeared to slip (over rev) when making scarp turns, decided to replace transmission filter and refill, the first run after 10 minuets the transmission went into limp mode (lights on drive selector started to flash) check engine lamp came on (P0734 and P0734) was read. the reason given was input and output ratio wrong for both codes.
      The Durmatic gave no other info. So I proceeded to  order both input and output sensors. Since I couldn't confirm if a shift selonod was bad. Mean while I am in Cal for the holidays I remembered I moved two of the magnets in the pan there were 4 magnets 2 each in the depressions in the rear of the pan I took one each and moved the forward closer to the input and output sensors.
      Anybody out there have any idea besides taking it to the dealer, at 75 bucks for the 5 liters of tranny oil each time I replace something to help me be smarter?
    • By sld
      transmission selector switch and unit repaired replaced 2 times and now it needs it again.
    • By crwarren11
      Hi all,
      After 18yrs my convertible top has finally encountered its first issue.  After using this forum (thank you!!) to figure out how to access all of the components (top was stuck in closed position), I found the root of my issue, a bad cable.  However, as I was very carefully removing the cable from the transmission, the "clip" which is molded into the plastic cover cracked and is no longer functional (see image).  Not really surprising on an 18yr old piece of plastic.  The transmission works perfectly and I do not want to replace it, so I am looking for advice on any other ways that I can keep the cable properly engaged to the transmission.  Please let me know if anyone else has encountered this and if there are any viable solutions.  Thank you!
       

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.