4t60e TCC problem?

[IsaacHayes]

Yeah, the shift and TCC control uses MAP input I believe. I was not referring to line pressure.

I've gone up hills before and before I can tell or the speedometer is registering I'm going slower the TCC unlocks as the engine becomes more bogged sounding. Tach really isn't changing either.

[3400-95-Modified]

TCC uses throttle % vs MPH to determine when to lock and unlock. There is no MAP info used. At least not in any tables that I can edit in a 96 and 97 ecm... I have no idea how a 94-95 OBDI.5 does it. Hell they dont even use RPM as a "critical" shift function.

[willyman82]

Modified: I am using a 1/8 inch NPT thread to hardline fitting to connect the trans pressure tap to a 1/4 copper tube. I checked the thread on the old trans and it goes in more than 5 turns by hand. Its not a perfect fit and will probably leak a bit, but I am running this to another fitting that I hooked up to my compression tester that goes up to 300psi. I will post a video on Youtube in the next few days. I bought enough tube to snake inside the car, but havent tried that yet. If I do Ill take some more video and edit it all together.

I will post a circuit schematic of the temporary fix for this once it is done, tested and working.

Thanks,
-William

[willyman82]

Test Drive Results:

1) Control (PWM sol and vacuum modulator hooked up) Torque converter shudder is experianced almost as soon as the throttle gets past 10%. Anything but driving straight and level at 70mph causes it to shudder. Line pressure is about 100psi when shudder starts.

2) TCC PWM solenoid disconnected yeilds a higher throttle position threshold before shudder is experianced. Higher throttle input causes the PCM to unlock the converter and all is well. Line pressure is around 150psi before being unlocked with shudder occuring and about 160psi after being locked up with 1/2 throttle.

3) Vacuum vent solenoid enabled yeilds higher opperating pressure as expected. 160psi at idle in OD and about 180psi on the highway at 70mph. TCC shudder is experienced just before the threshold of the ECM unlocking the torque converter at about 1/3 throttle. Pressure doesnt seem to want to go much past 180 when in drive (160 -180 depending on RPM). I suspect this is due to various blow off valves throughout the hydrolic valve body venting the excess pressure at 180psi.

4) Park pressure with vacuum actuator disconnected is over 200psi! Shifting into drive or reverse gives quite a jolt.

So based on all this data, I think the car would be perfectly drivable without signifigantly increasing line pressure if my proposed hack solution is implemented (increase line pressure and disable PWM sol when in 4th with TCC commanded from PCM). As soon as I am done and have tested the results, I will post schematics, diagrams and video links.

A funny side note is you can really hear the transmission pump LOUD inside the car with a spool of copper tubing filled with pressurized transmission fluid. I also got a very funny look from a cop that I passed heading back to the house with wires and 1/4 copper tubing snaked out the passenger window and under the hood :-)

-William

[willyman82]

Sorry that I havent posted any of the videos yet. I just havent had time to edit and upload them to utube.

I pulled the old trans valve body / channel plate / pump housing assembly off last night and found several things that were interesting.

The first thing I noticed was that all the bolts around the assembly were different torques. Some seemed way too tight and some were almost loose. I didnt think anything of it at first since they are all different lengths, but then I found more weird things. The TCC solenoid had a small O-ring stuffed in the small bore of the solenoid itself. I cant imagine where this could have come from inside the transmission, so I suspect it was put there intentionally (not by GM). The valve itself is actually steel!?!? It was sticking in the bore, so I couldnt get it out by using the return spring shoot it out. I ended up using a magnet as soon as I realized it was steel. It is not the sonnex valve with the teflon seal, but it is not the aluminum valve I was expecting either.

Has anyone ever pulled apart a 4T60E and found a steel TCC valve? Is it safe to assume that the original trans (262,000 miles) had been rebuilt before I bought the car at 100,000 miles? Maybe that is why it made it to 262K...

More to come as I get to upload videos and pictures and get further into the original valve body.

Thanks,
-William

[3400-95-Modified]

Measure the valve... Unless they changed in 96 and went to aluminum from the steel it should have been aluminum. Also with the O-Ring, there should be one on the TCC solenoid itself, but not in the bore between the valve and the solenoid if thats what you mean.

Also yes all of the VB bolts will be torqued differently... Check the book they are different depending on what size bolt they are.

Get pics of the spacer plate, and I can tell you if they put the trans go kit in it before... Also how bad was the valve sticking?

I have to go back and look at my pics of my other trans I did, but IIRC the original TCC was aluminum, and the one that I got with the new VB I bought was a purple anodized one since it was the oversized version that was put into that setup.

Actually I think I still have that valve body at home from the old trans... so I should have a 94 to compare.

[willyman82]

I will get pictures sometime this weekend. I doubt that I will have time to dig it apart before then. I can measure the TCC valve tonight. Just to make sure everything stays clear, this is a 95 vehicle with the WFW 4T60E varient.

There is 1 O-ring on each solenoid, except the PWM which has two. The TCC control solenoid had a 2-3mm ID O-ring stuffed in the hole in the middle of it. Could this have come from the TCC-SIG orfaced flow regulator? From the diagrams that is the only thing up the line from the TCC control solenoid. It doesnt look like anything could get past that from the pictures in the book. I havent actually seen it yet though. The only thing I can think of is that a transmission tech stuffed this in there during a rebuild to restrict flow through the solenoid for some reason. I dont see how this would do anything if the solenoid valve wasnt working properly. If anything it would cause the TCC to be lightly engaged all the time.

When I pushed the valve in from it's parked position it moved freely, but on a slow rebound I could feel something hanging up just slightly. When I tried your trick of letting go fast to shoot the valve out of the bore it just stopped when it hit the lip of the TCC-SIG orface. After trying a few times I realized it sounded funny when my screwdriver was making contact with the valve and thought it might be steel. So I tried my magnet and was able to pull it out without too much effort.

Thanks,
-William

[3400-95-Modified]

I've never seen an O-ring on the ID of the solenoid... Thats really odd...

and yes I would be looking at a similar trans, the valve bodies were all the same for 93 to 99 (may have just use different material valves) as far as I know. And I may actually have a 95 VB at home... i think the 94 one I did use before ended up going back as a core to someone, or maybe I just have both... lol