I just noticed something last night I have never seen before. To preface my question, I have a Yank SS3600 and a built(Art Carr supposedly) 4L60E without lockup(I'm working on it, tranny was built like this), and 1st through 3rd gears work 110%.

When cruising in 4th gear on the interstate, everything is nice and fine. If I accelerate lightly the car wil accelerate slowly liek it should. However, if I give it a fair amount of throttle, I can see the RPM's come up, and then about a second later I can see the RPM's drop ~300, and it feels like a clutch is softly locking up and then the car accelerates normally.

I tried it a bunch of times, and every time the RPM's will go up as normal, then drop a bit as something locks up or engages and then everything is fine until I let off and try it again. As far as I can tell the fluid level in the trans. is fine, but I have checked it probably 100 times and it's almost impossible to read the level, I know it's NOT low, but it may be too high. Every now and then when I stand on it I can smell tranny fluid(presumably from the vent), and it does this both when at full operating temperature and when warm. Maybe my fluid level is way high and I just don't know it???? Any ideas, or anything I can check? Thanks guys!

 

That sounds like lock-up

Frank
CPT

 

It sounds and feels exactly like lockup, but it's not, as the tranny does not have functioning lockup at this time. I have another thread about that elsewhere.... http://web.camaross.com/forums/showthread.php?t=536267 Say I'm cruising at 2500 RPM in 4th. I accelerate in 4th and the tach shows 3300 RPM. About a second later the RPM drops to 3000 and the car actually accelerates. It feels like a nice slow PWM engagement of a clutch pack. When I let off the RPM drops down to say 2700 and everything is fine again. It's like a flare of some kind.

 

Okay, so I pulled out 2 quarts of fluid, and now the fluid level is right where it should be. However, the problem is still there.

If I had to guess, I would say that it feels like line pressure is lagging behind throttle, meaning that when I squeeze the throttle in 4th it feels like something is slipping(4th gear band?) and then line pressure builds up and fully applies the band. That's what it feels like to me. Is this even possible, or is there any way to check? I have access to a Tech 2 or a Mastertech, so if there are any actual values I can check please let me know what to look for. Thanks!

 

I would agree it does sound likel lockup exactly , How is lockup disabled on the unit?

 

There is no lockup because there is no lockup solenoid in the tranny. I bought the trans and converter used like this. Apparantly it is a 1994(I was told it was a 1995 when I bought it) tranny using a universal internal wiring harness, and I am running it with a 1995 PCM, which shouldn't matter since there is no lockup or PWM solenoid in the tranny. I am assuming the tranny was modified by the builder to properly operate without lockup, whatever that entails. I am 100% sure it is NOT the converter trying to lock up. It was definitely NOT my choice to run without lockup, but it is what it is and I want to at least make sure I don't burn 4th gear up. I have the fluid running through the stock cooler as well as a good aftermarket cooler, and even on the hottest day beating on it the temp never got above 200.

I am going to hook the Tech 2 up to it today and monitor line pressure(assuming I can) and see what's happening with that first, as I don't know where else to look. Is it possible I have a cracked 4th gear servo?

EDIT: Could it possibly be that somehow the converter is PARTIALLY locking up, due to fluid flow/centrifugal force/magic/etc...?

 

MAGIC LOL. Na actually a 94 trans placed in a 95 will lockup it may set and electrical code for the PWM solenoid because its missing but it will still lockup , If theres a solenoid bolted with two 10 mm bolts going into the pump at in the pan then it has lockup, Your 95 trans would have also had a solenoid infront of the lockup solenoid called PWM that the 94 does not

 

Edit: Well, I just looked at the pictures again, and it appears that there IS IN FACT a TCC solenoid installed in this trans. I think the extra electrical connector threw me off when I looked at the pictures. Maybe it is very partially locking up, but I can guarantee that it does not lock up at cruise, probably due to the TCC solenoid DTC. SOoooooooo, I guess I either have a bad TCC solenoid or the absence of the PWM solenoid is causing the ECM to not command lockup.

Double Edit: Don't take my word for it guys, look at the pictures and tell me if that is the TCC solenoid I am seeing. I need reassurance here!

Pictures: http://touchofeden.smugmug.com/gallery/3209143#P-3-15
This picture in particular: http://touchofeden.smugmug.com/galle...9143#178289415


Thanks for all the suggestions so far guys, I sincerely appreciate the help!

 

Yes, that transmission has a lock-up solenoid in it.

Frank
CPT

 

Good! Now I'm finally getting somewhere. I know the PCM is setting a code for the PWM solenoid, and I believe this will inhibit lockup. Is this correct? If so I'll grab my old solenoid and plug it into the harness and let it dangle to fool the PCM.

 

All right! I took the car for a drive and used the Mastertech to control the TCC solenoid ON, and surprise surprise, it worked 100%! I am assuming the lack of a PWM solenoid and resulting DTC are inhibiting lockup, but at least I know the rest of the TCC circuit works. Now I just need to hook up a PWM solenoid or find another way to fool the ECM into thinking there is one present. Any ideas? If I don't have to drop the pan it would make me very happy.

Oh yeah, I still notice what feels like a bit of extra slip when I first accelerate in OD(locked up or not), but it's minor and I can't imagine what it could be, so I'm going to forget about it.

 

Well, after driving the car to work today I have realized that the slip in 4th is not really that minor. I know it is not the TCC clutch slipping now, as I can give it quite a bit of throttle in 3rd and not slip the TCC. My pressure control solenoid valve is also working as it should, varying duty cycle according to throttle. I have also noticed that the shift into 4th is very soft, though the shift into second and third are nice and firm, just as they should be.

Since 2nd gear shifts and works fine, what could be wrong with 4th? Do they use different accumulators/servos/etc..? To me it feels like there is a crack in a servo or accumulator causing pressure to bleed off. When I am steady on the throttle it holds fine, but if I quickly give it some gas it feels like it's taking a while to build up enough pressure to hold the band, letting it slip for about 2 seconds and then slowly locking it back up. If I give it light throttle or ease into it rather slowly it will not do this.

Does any of the above even sound plausible?

 

So yesterday I did a bit of work and soldered a resistor on the wire going to the PWM solenoid to fool the ECM. it worked and now I have lockup like I should. However, I am still concerned about the slipping I am feeling. Can anyone comment on my post above this one and tell me where I can start looking to figure this out? Thanks!


Edit: So I guess all it takes to run a 1994 4L60E with a 1995 ECM is one resistor. For some reason everyone on this board(when I did a search a while back) was making it sound like it was a huge mess to get it to work.

 

Any ideas guys?

Short version: Trans. slips in 4th gear only for a couple of seconds upon initial acceleration and then locks up until I accelerate again. What could it be?

 

Any ideas guys? Where can I start looking?