Hey guys, I was hoping to get some opinions here. I just got the M90 Roushcharger installed on my auto 2007 GT a few weeks ago, and some 3.73's installed at the same time. Instead of having the pcm shipped out to roush for a reflash, the shop suggested I have it dyno tuned with my diablo predator instead, which I thought sounded good, so I went for it. The car runs good, but since I picked it up it hasn't been shifting quite right, namely the 2-3 upshift. Driving normally or just gradually accelerating it shifts just fine, but around half throttle to WOT there is a pretty distinctive hesitation in the shift to 3rd. Like the nose drops down, stops for half a second, then goes strong again. There's no big clunk or bang, the car doesn't rev in neutral, no grinding or any weird sounds. Just a half second or so hesitation then a firm shift and away she goes. 3rd to 4th there is a very slight hesitation but not that bad. Now I've been hearing about these autos having a weak 3rd gear all of sudden and its scaring the crap out of me. Does this sound like a tuning problem or am I going to have to fork over a ton of cash to now have my tranny rebuilt? I had a Bama 91 race tune and intake on the car before the install and it ran/shifted awesome, no problems at all. Any opinions would really be appreciated, I'm looking at VMP right now and just hope to hell it's an issue with the tune.

 

Tuning. The 5r55s autos are a little tricky to tune right. Justin at VMP knows how to tune them; he should be able to take care of you!
When he did my blown-4.0L tunes, I had a few issues with when shifting would occur (hanging too long before shifting, mainly under WOT or heavy throttle when spinning tires), and he got it all adjusted nicely by lowering when the shifts would occur. That was more of a timing/rpm/speed issue and not smoothness or crispness of the shifts; that was always good. My current tuner has my trans adjusted quite nicely as well.

But you do need to keep in mind, there a couple of "weak" points in the 4.6 auto trans, including the 2 servos and the input shaft. You can upgrade those for around $350 in parts and get much stronger protection against those weak parts. (Search and ye shall find!)

 

Thanks for the reply man, that puts my mind more at ease. I suspected right away it was just my tranny not tuned right, but when I started reading a few threads pertaining to the auto having some weak points, it suddenly got me wondering. I will definitely be going with Justin at VMP for some tunes and upgrades pretty quick here. Thanks again.

 

Dyno tune is great but it does nothing for tuning the trans. I know VMP knows Roush blowers well but I have not read a lot about their tuning of the auto trans. JDM is an expert in that trans. I have their tune and love it. I would call both of them and talk it over. Brenspeed is another great auto trans tuner and yes they do tune for roush blowers.

 

+1 on believing it's the tune. I wouldn't sweat it until you get the correct tune and still see problems. The shop that did your tune likely isn't familiar with the PCM changes required that affect the tranny.