Hey guys, I searched the threads and found similar issues but nothing exactly like what I'm experiencing. My 2000 T/A has a new (less than 3k miles) 4L60 from BTE Performance Transmissions. Supposedly it has all the upgraded
goodies, but I'm thinking I have an issue in the valve body. When I'm cruising around town or on the highway the car seems to drive fine, but when I get into the throttle pretty good it hangs up in 2nd gear and will not up shift until I let off the pedal. It doesn't do it every time, but it happens often. It will hit the rev limiter if you stay in it long enough.

I've already tried all the simple fixes, I've had the tune checked for shift points and proper converter settings, it has a Yank 3600. I've tried replacing the TPS and VSS hoping it was a sensor issue. I added extra fluid as I have seen that advised on these transmissions, but no luck so far. With the transmission being so new I hate to think it's faulty parts, I'm going to call and see if anything can be done to help me out warranty wise after the holiday weekend. If they won't help me out, I need to know what I need to replace in this thing.

At this point I'm leaning towards a bad or sticking solenoid. Could it be a valve body wiring harness issue or possibly something else? Someone else on here had an issue with the 3rd gear accumulator check ball in the servo area. If I drop the pan and decide to tackle are there any other components I need to replace while I'm in there that could cause this? Any advice is appreciated!

This is a better description of what my car is doing, basically feels like neutral at high rpms after the failed 2-3 shift until you let off the throttle.

 

I forgot to mention that we hooked it up to a scanner today and it is commanding the shift and it isn't throwing any codes besides the usual EGR stuff from some mods.

 

If the PCM is commanding a shift and it doesn't happen within a quarter second, then there is a trans problem.
It could be as simple as a bad/sticking/clogged solenoid. With solenoids only $12 that sure is worth a try; at a minimum replace the "B" solenoid.
While various valves in the Valve Body (VB) do move for the shift, I don't recall a single thread here where a 2-3 shift issue was due to a VB problem other than a bad solenoid. Always a first time though.

Glad you already added the extra 1/2 quart fluid.

You have done your research well to note that a bad 3rd accumulator check ball could be the culprit. While I have mentioned this many times as a problem area, the pros have told me it isn't as common as I had implied. While non-trivial, this check-ball cartridge can be replaced after removing only the valve body, although I would also remove the servo for visual confirmation.

Other problems in the servo area could also be the culprit. These are a cracked 2nd gear servo piston, worn/torn seal for that piston, or excessively worn servo bore in the case. Unfortunately its non-trivial to remove the servo in many cars due to clearance issues. (But easy in trucks.)

One of my personal builds developed the exact problem you described. It turned out a tiny sliver of metal had cut the seal on the 3rd apply piston in the input drum. I obviously had to pull and disassemble the trans to diagnose and correct this. I obviously didn't clean all the parts well enough when I built it.

Hopefully your problem is simpler. Unfortunately the 4L60e's design has many places where the 3/4 apply fluid can leak.

 

Thank you for the quick and detailed reply, mrvedit! I dropped the pan earlier. My solenoids a should be here tomorrow, I'm going to keep my fingers crossed and hope that solves my problem. Although after finding a small metal burr in the pan while wiping it clean, I'm afraid it may be as you've said.

If the solenoids don't do it, the next step would be to pull the servo to check for any damage, correct? It has a billet servo, if there does happen to be any damage I'm hoping BTE will work with me on getting a replacement. I just hope I don't have to pull the transmission to get it out or to further investigate the problem! That's a little over my skill level when it comes to auto mechanics.

I asked a local transmission shop about the problem and he said if it wasn't the TPS then it was failing clutches. That didn't sound right to me since it's not slipping, it works right sometimes, and the fact that it has hardly any miles which are from cruising and no hard abuse. He suggested a complete $1500 overhaul, which I can't afford right now. I'm hoping and praying it doesn't come down to that.

I'll let y'all know if the solenoid a happen to work for me after I stick them in tomorrow.

 

After doing a little more research while bored at work tonight, I stumbled onto a possible new fix. Probably too good to be true since it's so simple though, but would a defective MAF cause this problem? I see where some guys had trans problems related to the MAF. Since the computer is commanding the shift I doubt that would be it, but just curious. Would unplugging the MAF be a way to test this theory?

It has always thrown a P0xxx code, can't remember exactly which one, due to the previous owner removing some of the EGR.

 

Hooking up a pressure gauge is the proper way to diagnose a trans that is slipping.
I really should have mentioned that in my earlier post.
If the pressure if fine, the next step is to check the items I listed to determine where the 3/4 pressure is leaking.
If the pressure is low, then the PCM is reading a faulty engine sensor, the PCS (Pressure Control Solenoid) is bad, or the PCM has a bad tune. This current thread covers many of the same points:
https://ls1tech.com/forums/automatic...ft-issues.html

The $35 ATD-5550 pressure gauge has a long hose and you can watch the pressure through the window while you drive and make the trans shift at e.g. WOT.

 

I replaced the B shift solenoid, pulled the pressure control solenoid, inspected and cleaned it, but still no luck. I'm going to see if my mechanic friend can help me check the pressure for the next step as has been suggested.

I drove it to work tonight to test the solenoid out, and while playing around I did discover that if you leave in with the gear selector in 3rd at wot and shift into OD before the 5800 rpm shift point is met then the trans shifts into 3rd gear as it should. Until I can diagnose and fix the problem, I'll just shift it like that manually if I want to play. I'm hoping it's fine to drive the car as it is since it's not actually slipping.