i just finally installed my circle d billet convertor in my 04 yukon. the tranny was recently built hopefully for my power range. it seems like it doesnt know what gear to be in and sometimes doesnt feel like its engaging second and doesnt seem to grab fourth at all, just revs. the stall is 3k or so not sure, but the hp tuners was tuned for a stock convertor. could the tune be causing the issue. fluid is full and everything is connected properly. any ideas?

 

did you do any other mods at the same time ?? like servos ?

 

it has upgraded servos not sure which one, it had a corvette servo before not sure if it was reused. has billet shafts, upgraded pump, shift kit, alto clutches, and wider bands. it seems really twitchy. you have to be very light with the throttle for it to shift to 2nd and so on. never engages 4th. we tried locking it 4th with hp tuners and nothing happened. convertor clutch isnt doing anything with hp tuners. when we try locking it 2nd it doesnt engage till like 4200 but it only does that in 2nd.

 

It needs to be tuned.

Is your Service Engine Soon light on? If so it's from your transmission going into limp mode which will keep your transmission from shifting into 4th.

 

The higher stall speed of the converter may be confusing the PCM into thinking that the trans is slipping. There are a few things in the tune that need to be adjusted and some codes that must be turned off. Get the tune straightened out first then take it from there

 

How many quarts of fluid did you use you dont need to re tune it did you lock the converter all the way in ?????

 

Mine is acting the same
Way... It has to be a tune.. I
Installed it like 1 week and half ago...

 

convertor is for sure all the way in. even shimmed it with two washers to get proper spacing. fluid levels have been checked was about 12 or 13 quarts i guess. was overfilled slightly thinking maybe it needed more. no codes are coming up on a matco scanner. midcoast performance did the original tune ans they used hptuners to request4th and nothing, requested lockup and nothing. when he requested 2nd nothing till about 4200 or wait a few seconds and it might engage. weird stuff. acting like it low on fluid to me , but seems a tune could help but they say since its not responding like it is that its not just the tune?!? i agree with them also

 

You absolutely need to retune the PCM when you install a higher stall speed converter, for the reasons that I mentioned above. Without a retune, you may experience shift solenoid codes, trans slipping codes, and limp mode which will start you off in 3rd gear, and is murder on the 3-4 clutches. Since the trans is "built", there are other things that should be addressed also, such as adaptive learning being turned off, shift speed/time being adjusted, and line pressures set to stock. There are different forms of torque management that should also be addressed at this point. If you install a high enough stalled converter and don't adjust the PCM logic accordingly, you're just asking for problems, and possibly burnt 3-4 clutches.

After the tune has been properly adjusted, and that definite problem has been eliminated, the OP can go after diagnosing possible automatic transmission mechanical issues that may or may not be the fault of the trans builder.

 

Very well said, thanks. The tune should fix the issues, if not post back and let us know. We will get it taken care of, no worries.....

Chris