Shudder on WOT 1-2 shift

[8nutz8]

Was doing some practicing brake boosting from a dig and shifting into second gear the trans would seemingly shift, then shudder for a second, and then what if feels like shift again and take off as normal. This started to occur a few nights ago and hasn't been consistent but has done it a handful of times since it started. I've done some searching and reading and i'm a little confused as if i should be diagnosing hard parts . . trans,PTU, TC, or address the issue through the tune. The car only has 14k on it and has only been tune for about 3-4 weeks but that doesn't rule out any hard part failures. I'll be loading the stock tune again soon to see if the problem still occurs at stock power levels and trans settings.
What's the consensus from others who have experienced the "shudder"? Was it a tune issue or a hard part issue?

TIA

 

[ZSHO]

I think the [Winter Blend gas]is upon us unfortunately and would try ruling that out or it being bad gas especially if your issue just started in the last few days.....do you have access to 93 octane fuel such as Shell,BP,Chevron? 

 

[8nutz8]

highly doubt bad gas is the issue here. I've filled up at only one gas station since I've owned the car the past 6 weeks and it's the gas station I've been frequenting the past 5 years with all my vehicles and never had an issue winter gas or not. also, not sure how bad gas would cause intermittent shifting/shudder issues. car is not missing or sputtering and has no issue other than shifting into 2nd at WOT. seems to occur more frequently when doing a brake boost launch more than going wot from a low 5-10mph roll. hoping it's not a TC issue. I know brake boosting for too long can swell the TC but I always make sure not to stand on the brakes for more than second or two before launching.

 

[ZSHO]

highly doubt bad gas is the issue here. I've filled up at only one gas station since I've owned the car the past 6 weeks and it's the gas station I've been frequenting the past 5 years with all my vehicles and never had an issue winter gas or not. also, not sure how bad gas would cause intermittent shifting/shudder issues. car is not missing or sputtering and has no issue other than shifting into 2nd at WOT. seems to occur more frequently when doing a brake boost launch more than going wot from a low 5-10mph roll. hoping it's not a TC issue. I know brake boosting for too long can swell the TC but I always make sure not to stand on the brakes for more than second or two before launching.

I have seen many issues with the winter-blend gasoline causing a host of issues including a shudder on this platform especially while being tuned and simply was trying to rule out the cheapest option for ya . Z . 

 

[SHOdded]

What was the ambient temp when the issue occurred?  Was the car warmed up prior to WOT?  What tires are you running, how much tread, and what psi?  Insufficient traction can lead to hop/stutter.  So can aging transmission fluid.

 

[8nutz8]

highly doubt bad gas is the issue here. I've filled up at only one gas station since I've owned the car the past 6 weeks and it's the gas station I've been frequenting the past 5 years with all my vehicles and never had an issue winter gas or not. also, not sure how bad gas would cause intermittent shifting/shudder issues. car is not missing or sputtering and has no issue other than shifting into 2nd at WOT. seems to occur more frequently when doing a brake boost launch more than going wot from a low 5-10mph roll. hoping it's not a TC issue. I know brake boosting for too long can swell the TC but I always make sure not to stand on the brakes for more than second or two before launching.

I have seen many issues with the winter-blend gasoline causing a host of issues including a shudder on this platform especially while being tuned and simply was trying to rule out the cheapest option for ya . Z .

right. I appreciate it. but I trust the gas. it's chevron 91. can't get 93 here but it's a 91 tune also so. . .

anybody else had this issue and care to speak up?

 

[ajpturbo]

Might need some ajp turbo tune-age

 

[FoMoCoSHO]

Its the tune.

Both of mine did it but but its not been an issue since I switched.

Actually that is one of the reasons I switched, I got tired of my trans being "on murder"

 

[8nutz8]

thanks for the replies guys. ambient temps were in the 70s and car was fully warmed up. haven't been to the track yet for times and psi at top of first is 12-14. highly doubt it's a traction issue I can barely get the tires to break loose on a brake "boosted" launch. trans fluid looks good and car only has 14k on it. trans service will happen soon regardless

my first suspect was the tune

 

[8nutz8]

Might need some ajp turbo tune-age

You'll be getting a pm sometime soon

 

[2013BlackSHO]

highly doubt bad gas is the issue here. I've filled up at only one gas station since I've owned the car the past 6 weeks and it's the gas station I've been frequenting the past 5 years with all my vehicles and never had an issue winter gas or not. also, not sure how bad gas would cause intermittent shifting/shudder issues. car is not missing or sputtering and has no issue other than shifting into 2nd at WOT. seems to occur more frequently when doing a brake boost launch more than going wot from a low 5-10mph roll. hoping it's not a TC issue. I know brake boosting for too long can swell the TC but I always make sure not to stand on the brakes for more than second or two before launching.

I have seen many issues with the winter-blend gasoline causing a host of issues including a shudder on this platform especially while being tuned and simply was trying to rule out the cheapest option for ya . Z .

right. I appreciate it. but I trust the gas. it's chevron 91. can't get 93 here but it's a 91 tune also so. . .

anybody else had this issue and care to speak up?

I had this happening for a while in my '13.
I had drained/filled my trans fluid three times and it was very close to gone but still slightly there.
I saw Livernois post on SHOForum that these transmission are happier with a pint above full on the trans fluid. I added a pint that day and it's never come up since then.

 

[8nutz8]

^ good call I've seen that as well so I'll give her some fluid to see if it helps. ultimately I think the issue should be addressed through the tune though

 

[ajpturbo]

^ good call I've seen that as well so I'll give her some fluid to see if it helps. ultimately I think the issue should be addressed through the tune though

Yes yes, very addressable it is lol.

The shift adjustment is more involved than just pressure changes....I actually run high pressures but lower torque reductions

Contrary to popular belief, the factory tq reductions and tq management don't really get in the way of quick, firm shifts....You can have fast shifts with tq reductions in the name of drivetrain preservation

I used to lower shift pressures to avoid the 1-2 shudder, it was not the way....It kind of worked but not really

 

[Livernois Motorsports]

^ good call I've seen that as well so I'll give her some fluid to see if it helps. ultimately I think the issue should be addressed through the tune though

The shudder is actually primarily caused by fluid cavitation. As the fluid gets more hot and less viscous it will incorporate more air. Thus, creating cavitation. This has NOTHING to do with a tune.

 

[FoMoCoSHO]

^ good call I've seen that as well so I'll give her some fluid to see if it helps. ultimately I think the issue should be addressed through the tune though

The shudder is actually primarily caused by fluid cavitation. As the fluid gets more hot and less viscous it will incorporate more air. Thus, creating cavitation. This has NOTHING to do with a tune.

If your trans is on murder and everything is getting hotter, wouldn't that contribute to the issue in a indirect way?

 

[Livernois Motorsports]

The root is still physics. I guess if you want to make an existential connection there is always a way to do so.

 

[ajpturbo]

^ good call I've seen that as well so I'll give her some fluid to see if it helps. ultimately I think the issue should be addressed through the tune though

The shudder is actually primarily caused by fluid cavitation. As the fluid gets more hot and less viscous it will incorporate more air. Thus, creating cavitation. This has NOTHING to do with a tune.

You are going on the assumption that cavitation is the cause....if the tune is the problem then is has EVERYTHING to do with the tune

Perhaps i dont suffer fluid cavitation...how does one prove that fluid cavitation is the problem or even present?

 

[Livernois Motorsports]

VIA our R&D we have already found and proven that the STOCK vehicle has this issue. It can also hold gear and bang off of the limiter. SO, if the hot completely stock car can suffer from this how exactly is it tune related? We know because we are often tasked with the job of finding these types of issues with factory platforms.

 

[FoMoCoSHO]

VIA our R&D we have already found and proven that the STOCK vehicle has this issue. It can also hold gear and bang off of the limiter. SO, if the hot completely stock car can suffer from this how exactly is it tune related? We know because we are often tasked with the job of finding these types of issues with factory platforms.

Interesting.

I've experienced it in both cars when tuned, never stock.

If heat is the factor then removing TQ reduction on shifts would exacerbate the situation, correct?

Does the extra pint of fluid help mitigate this without harming the trans?

 

[SHOdded]

I wonder if extra fluid could help the 6f50 also.