Notices
993 Turbo Forum 1995-1998
Sponsored by:
Sponsored by:

Does this happen in your 993tt while shifting?

Thread Tools
 
Search this Thread
 
Old 05-01-2018, 08:05 PM
  #1  
Matute
Track Day
Thread Starter
 
Matute's Avatar
 
Join Date: Mar 2018
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
Default Does this happen in your 993tt while shifting?

This is a 32k kms Car with theoretically no other mod than tail pipes.

This happens when you step on the clutch to shift gears



Last edited by Matute; 05-01-2018 at 08:05 PM. Reason: Unfinished
Old 05-03-2018, 09:45 AM
  #2  
Quadcammer
Race Director
 
Quadcammer's Avatar
 
Join Date: Nov 2006
Location: Clifton, NJ
Posts: 15,629
Received 1,371 Likes on 794 Posts
Default

nope. Are you sure you are off the gas fully when getting the clutch in?
Old 05-03-2018, 09:52 AM
  #3  
Matute
Track Day
Thread Starter
 
Matute's Avatar
 
Join Date: Mar 2018
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
Default

Yes 100000% Sure.... so far I have narrow it down to the isv. I have change it for a new one, also the diverter valves and tps but the problem persists
Old 05-03-2018, 10:09 AM
  #4  
LexVan
Banned
 
LexVan's Avatar
 
Join Date: Jan 2013
Location: Chicagoland Area
Posts: 26,142
Likes: 0
Received 5,388 Likes on 2,509 Posts
Default

Hard to tell from that short clip. Are you getting slippage on your clutch? Meaning, car in gear, try 4th or 5th, on boost, full acceleration, do the RPMs blip up before the clutch grabs?

Other things to consider are the throttle position sensor.

Make sure your floor mat is not interfering with your pedals.
Old 05-03-2018, 03:01 PM
  #5  
Matute
Track Day
Thread Starter
 
Matute's Avatar
 
Join Date: Mar 2018
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
Default

The revs go up exactly after I press fully on the clutch... it is when the engine is free from the clutch + transmission that that slight acceleration peak occurs. So for me it is impossible to be the clutch slipping.

have also swapped the tps and got rid of the floor mat long time ago
Old 05-03-2018, 09:55 PM
  #6  
PiB993
Rennlist Member
 
PiB993's Avatar
 
Join Date: Jun 2012
Location: San Francisco, CA
Posts: 1,202
Received 151 Likes on 99 Posts
Default

My car does this but not as abruptly as yours. The revs hover upwards for a second and then drop. Your video looks like your are still on the gas. Now if I carry into the higher rev band it drops immediately (more friction? BHP pulling the revs down?)
Old 05-03-2018, 11:01 PM
  #7  
Matute
Track Day
Thread Starter
 
Matute's Avatar
 
Join Date: Mar 2018
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
Default

Thank you ... at last someone that has the same issue. Yes mine also stops doing it at a higher power band. It really only happens between 2.5k and 4.5k rpm.

have you ever asked any mechanic about this issue?

thank you
Old 05-04-2018, 12:14 AM
  #8  
golfnutintib
Rennlist Member
 
golfnutintib's Avatar
 
Join Date: Sep 2014
Location: ..............
Posts: 3,859
Likes: 0
Received 44 Likes on 36 Posts
Default

my 993tt does not do that
Old 05-04-2018, 01:33 AM
  #9  
PiB993
Rennlist Member
 
PiB993's Avatar
 
Join Date: Jun 2012
Location: San Francisco, CA
Posts: 1,202
Received 151 Likes on 99 Posts
Default

I have not asked my mechanic about it. He drove the car earlier this year. You would not notice it on my car unless you were watching the revs. Mine doesn't spike up rapidly like yours in the video. Going through the gears the revs 'float' up and sustain a second in-between shifts before dropping. Throttle position sensor was replaced a few years ago trying to solve the p1140 code. I will admit it is a bit annoying but I have grown accustomed to it as everything is working fine otherwise and passes smog.
Old 05-04-2018, 11:14 PM
  #10  
OverBoosted28
Rennlist Member
 
OverBoosted28's Avatar
 
Join Date: Nov 2010
Location: Central California
Posts: 3,484
Likes: 0
Received 12 Likes on 11 Posts
Default

Maybe it’s something as simple as your throttle cable is fraying, and it’s slightly hung up? When ya, press in clutch, the cable might be hung up in sheathing, and not letting revs drop. It might be so fine, that it hasn’t been noticeable, when starting/taking off, but as you get into revs, it’s more noticeable? Another angle to look at. I assume most items that haven’t been replaced, will need to be, on my car. This is one of many, on my list of “to do’s”.
Old 05-05-2018, 12:48 AM
  #11  
AC/911's
Banned
 
AC/911's's Avatar
 
Join Date: Aug 2010
Location: Double Secret Probation
Posts: 2,074
Received 94 Likes on 49 Posts
Default

Nothing to do with problem, But for a Low Km Car, That tach looks to have been in & out a few times...


.
Old 05-07-2018, 01:31 PM
  #12  
PiB993
Rennlist Member
 
PiB993's Avatar
 
Join Date: Jun 2012
Location: San Francisco, CA
Posts: 1,202
Received 151 Likes on 99 Posts
Default

I was driving the other day and doing a hard pull in 3rd or 4th and it was pretty much exactly as the OP's video. Not sure how the turbos work on this car but could it be boost/waste gate (?) not correctly releasing pressure when lifting off the throttle [or rather, releasing clutch engagement/pressing clutch pedal in]?

Matute do you have an aftermarket muffler? Just curious because your car sounds a little more raw than mine. Oops nvm -

Last edited by PiB993; 05-08-2018 at 09:16 AM. Reason: strikeout - clutch comment in brackets
Old 05-07-2018, 11:17 PM
  #13  
DiegoR
Burning Brakes
 
DiegoR's Avatar
 
Join Date: May 2013
Location: Peru
Posts: 929
Received 19 Likes on 8 Posts
Default

Originally Posted by PiB993
I was driving the other day and doing a hard pull in 3rd or 4th and it was pretty much exactly as the OP's video. Not sure how the turbos work on this car but could it be boost/waste gate (?) not correctly releasing pressure when lifting off the throttle?

Matute do you have an aftermarket muffler? Just curious because your car sounds a little more raw than mine. Oops nvm -
I would say IMPOSSIBLE to be related to boost/turbos for that hickup or strange behavior of the RPM when press the clutch.

Mine doesn't do it or at least that I have not noticed it.

OP, did you change something recently or this behavior showed up by itself from the nowhere?
Old 05-07-2018, 11:30 PM
  #14  
Matute
Track Day
Thread Starter
 
Matute's Avatar
 
Join Date: Mar 2018
Posts: 23
Likes: 0
Received 0 Likes on 0 Posts
Default

I bought the car recently and it has always done that. Please note that when I disconnected the isv and open a little the throttle body the problem was almost gone.

So the temporary solution would be to drive with the isv unplugged. But i would really like to solve this issue definetly, considering it is a 100k usd plus car.
Old 12-25-2018, 08:50 PM
  #15  
PiB993
Rennlist Member
 
PiB993's Avatar
 
Join Date: Jun 2012
Location: San Francisco, CA
Posts: 1,202
Received 151 Likes on 99 Posts
Default

Sorta simular situation for 997 GT2

https://rennlist.com/forums/997-gt2-...-upshifts.html

My car does it when I am harder on the throttle and it will blip just like OP.


Quick Reply: Does this happen in your 993tt while shifting?



All times are GMT -3. The time now is 09:12 PM.