well, i installed a used sy3500 in my car today and am having some serious problems. about 3 weeks ago, i had the pcm tweeked in anticipation of the install... rpm in drive and reverse set to 650 rpm and shift firmness up'd a little bit. the trans was just fine before today. oh, and i changed the filter during the install, too. followed the modern muscle car website's directions for install to a t, also.

1) although the level seems fine, the tc rattles like hell if the car has sat a while with the engine off.

2) the tc will unlock at the slightest provocation of throttle and hunt between locked and unlocked at light throttle.

dexronIII went in it and, like i said, the level has been checked a couple of times and topped off accordingly. when i first started the car, the tc rattled like hell and then quieted down. i placed the car into reverse and the tc rattled again. i checked the fluid level and topped off and all was good until i placed the car in drive. same thing as with reverse... topped off and all was good. i let the car run a bit in park, bringing the temp up and then shut her off. about 2 minutes later, the trans belched a huge air bubble, shooting fluid all over my engine compartment (tube was out). so, i checked the fluid and drove the car for about 5 mins.

the tc was much looser than stock, but that improved after the drive, however the tc was having problems locking as described above. after the drive, i left the car running to check the fluid level again. when i pulled the dipstick, a fair amount of pressure came out of the tube again, but no fluid this time. i added a bit more and went for another 5 minute spin. it was still having the same problems locking, but everything else seemed okay. upon my return, i checked the level again and a bit of pressure came out of the tube, but nowhere near as much as the previous two times. unfortunately, i can tell if there is a leak as that the fluid explosion dumped so much fluid that it will be dripping off of my car for a while.

i checked the vent tube, but it isn't pinched and, like i said, the level seems to be fine. any ideas???

 

It sounds to me like the tc was not properly filled with fluid before it was installed.

 

1) Double check the fluid level
2) Reset the PCM so it learns from scratch with the SY 3500 in it.

 

i filled the 'verter almost up to the top of its body. fluid lvl is still fine and the car set overnight with the battery disconnected before the 'verter went in. is there anything special that you have to do to fill it? it had a fair amount of fluid in it when i got it from the previous owner. i just added fluid until it reached to about the top of the converter's body as viewed through the shaft. won't the transmission pump more fluid into the converter? i drove it for about 10 miles today... the level is still fine, although i got a pretty big release of pressure when i pulled the dipstick. the converter still makes noise after sitting for about 5 seconds and it still won't lock properly. i am worried that i may harm my transmission with all the pressure it builds up and am thinking about putting the stock one back in.

 

The lock/unlock could be related to missfire issues. the lighter weight t/c has less rotating mass which the PCM precieves as missfires, the rattling only makes it worse I assume. High missfires counts with either cause the pcm to not lock it up or randomly unlock the TC.

 

that is good information. however, if i am on perfectly flat ground and set the cruise control, it will stay locked. if i give it just a bit of gas, it will unlock/lock repeatedly, like every .5-1 seconds, until i give it enough gas (maybe another 1/8th pedal) to unlock it. it unlocks WAY easier than the stock converter. i think the converter is broken. none-the-less, i'm gonna put the stock one back in and hope everything is okay.

 

I think the misfire issue is your problem and that wants
programming either to raise threshold or, more likely, to
fix some part-throttle misfire / stumble. If it "rattles"
that is abnormal and maybe the "rattle" is really crank
jerk or audible misfiring.

Any chance that the "rattling" may really be the pump
splines not properly seated and skipping rather than
holding quietly? That would suck, and suck worse very
shortly once they had a chance to grind some more.
Converter seating is something that does get screwed
up on occasion, not fully engaging the TC to all the
input shaft spline sets.

If you have any buddies with ATAP / EFILive / HPTuners
at least go get a read on misfires, TCC mode, etc. and
you probably are looking at another tuning session.