1-2 shudder at WOT

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donky4444

New member
So I'm getting a shudder on the 1-2 shift when at WOT. That's the only time it happens is this a common problem and a sign of something coming?  I have just shy of 60,000 miles, I had the trams flushed last summer and the RDU fluid changed at the sa,e time. PTU has not ben touched. I'm going to go back to stock tomorrow and see if I can replicate it to rule anything funny with the tune. I'll be stopping in the dealership on Friday so I hope it's something that I can replicate when stock since I'm under warranty.
 
PTU can of course be an issue, but so can bad gas, fuel injector, and spark plug.  No codes, I'm assuming?  Any oil in the plug wells (valve cover gasket leak)?  Excessive oil in the intake/CAC?
 
SHOdded said:
PTU can of course be an issue, but so can bad gas, fuel injector, and spark plug.  No codes, I'm assuming?  Any oil in the plug wells (valve cover gasket leak)?  Excessive oil in the intake/CAC?
Click to expand...

I'll check for codes tomorrow when I go back to stock. The shudder is only at the 1-2 shift. Almost feels like wheel spin or hop. Other then the shift she pulls strong and hard until I get out of it. That is what makes me think it's trans/driveline related.
 
Donky, before you do anything hasty and go to the dealer ask LMS what your 1-2 WOT shift pressure is near redline. If you have anything near or north of 220 that is too much pressure. I see that you have a 4x tune...I'm not really sure what that is in the Livernois world but I'm going to guess it's on the aggressive side.

I had the shutter also. Others were talking about wheel hop...I didn't think that's what it was but I just figured if that's what everyone was saying I went with it...I lowered my pressure to about 200 and it hasn't done it since.

I only noticed mine after a reflash but after the tune aged a little the adaptive for oncoming shift elements lowered the pressure a bit and I wouldn't get it. I think that's why some people may notice quicker shifts after a reflash. It's just because the adaptive hasn't kicked in yet, the adaptive can be disabled completely or the amount of adaptive can be redefined as to how much or little is applied and where and when lol..It's complicated....Also I found in my strategy the 2-3 pressures are really high even in part throttle...I lowered them as well so even after a reflash the 2-3 isn't so rough....Hope that helps...The shuttering to me almost sounds like tranny slipping but I've read that it's just not catching the gear and not as bad as it sounds but I'm not sure
 
I think bosscav had his SHO's shift pressure adjusted by LME to correct that stutter in the 1-2 shift, and it's working great for him.  Maybe that IS the fix for Don's SHO also.
 
It has to be the shift pressure...4x plus tune is given out with the warning...."track tune"...not daily driver. Thing is, it's perfectly fine unless WOT from a dig. Then you get the little stutter on shift from 1-2. So if your driving around going balls out all the time, get it softened or switch to another tune. If not, save those WOT pulls for meaning and don't sweat it.

Rich
 
91hybrid said:
Very interesting. Wouldn't lowering the shift pressure cause the transmission to slip more during the shift?
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I don't actually think it's a slip issue...it's more of something not catching like it needs more time to engage the next gear and with too much pressure being commanded in the oncoming element tables u are not giving it enough time....that's my guess I could be wrong..but I know lowering the pressure to 200 down from 220 helped and I didn't like how the shuttering sounded at all
 
FoMoCoSHO said:
It's really nice having AJP around to explain all this tuning **** to us

Thanks!
Click to expand...

Thanks fomo...Well I'm not a pro and I'm sure I will get corrected from time to time...but I'm deep into it and I know some things that will help..I've wasted too much money on software and tunes and should've been happy before with what I had but I can't leave well enough alone plus I enjoy it..

I've had a couple bad tunes before from big names that left me jaded so here I am
 
ajpturbo said:
FoMoCoSHO said:
It's really nice having AJP around to explain all this tuning **** to us

Thanks!
Click to expand...

Thanks fomo...Well I'm not a pro and I'm sure I will get corrected from time to time...but I'm deep into it and I know some things that will help..I've wasted too much money on software and tunes and should've been happy before with what I had but I can't leave well enough alone plus I enjoy it..

I've had a couple bad tunes before from big names that left me jaded so here I am
Click to expand...
Well, I came from a forum where the vendors actually explained things and even helped the guys with the Pro Race package. This forum is quite different as everyone is sooooo worried about their "proprietary tuning" blah, blah, blah. This stuff fascinates me and I just want to learn how it all works.
 
SHOdded said:
Here's some basic info related to transmission shift pressure:
http://freeasestudyguides.com/transmission-pressure-control.html
http://en.wikipedia.org/wiki/Transmission_control_unit
Transmission Pressure Control Solenoid (PCS)
Transmission Shift Solenoid

We are able to "tune" these parameters because of the move to shift and pressure control solenoids.
Click to expand...
Thanks Manu.  As always, a timely reference to help me and the rest of the group who really should understand more about how our cars actually work.
 
FoMoCoSHO said:
It's really nice having AJP around to explain all this tuning **** to us

Thanks!
Click to expand...
I wouldnt call the tuning (****) but AJP perspective and input on tuning is greatly appreciated from my point of view,just a little less bashing on vendors like LME would be nice,and that 3-bar **** is getting kind of old,LOL.Z
 
It seems that this is only an issue at WOT high RPM 1-2 shifts and is somewhat sporadic.  Does lowering the pressure to eliminate the 1-2 stutter result in a "lag" during the shift similar to stock tune....or is is still firm and crisp but without the stutter?   

If you were going to the track, would you want the higher pressure and potential stutter or would you want the pressure dialed back?  Like others, I have experienced this after a reflash but it typically calms down some after driving awhile and has never occurred at less than WOT.
 
Brucelinc said:
It seems that this is only an issue at WOT high RPM 1-2 shifts and is somewhat sporadic.  Does lowering the pressure to eliminate the 1-2 stutter result in a "lag" during the shift similar to stock tune....or is is still firm and crisp but without the stutter?   

If you were going to the track, would you want the higher pressure and potential stutter or would you want the pressure dialed back?  Like others, I have experienced this after a reflash but it typically calms down some after driving awhile and has never occurred at less than WOT.
Click to expand...

The shutter sounds bad..I wouldn't want it even at the track...and reducing the pressure to say 200 is still well over stock and won't give a laggy shift at all...at wot is where the highest pressure is
 
ZSHO said:
FoMoCoSHO said:
It's really nice having AJP around to explain all this tuning **** to us

Thanks!
Click to expand...
I wouldnt call the tuning (****) but AJP perspective and input on tuning is greatly appreciated from my point of view,just a little less bashing on vendors like LME would be nice,and that 3-bar **** is getting kind of old,LOL.Z
Click to expand...
Honestly Z, that wasn't a dig on LME, it was a statement about tuning in general. It's like Mandarin to me and its nice to have someone around who can translate it.
 
FoMoCoSHO said:
ZSHO said:
FoMoCoSHO said:
It's really nice having AJP around to explain all this tuning **** to us

Thanks!
Click to expand...
I wouldnt call the tuning (****) but AJP perspective and input on tuning is greatly appreciated from my point of view,just a little less bashing on vendors like LME would be nice,and that 3-bar **** is getting kind of old,LOL.Z
Click to expand...
Honestly Z, that wasn't a dig on LME, it was a statement about tuning in general. It's like Mandarin to me and its nice to have someone around who can translate it.
Click to expand...
Understood(just to clarify things up due to context)the only statement against you was twards the comment about tuning ****,the rest was directed twards AJP.
 
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