700R4 TCC shudder

Guys, I have been having a problem with the tranny in my 91 CC that are absolutely driving me nuts! I had thought I had engine issues but now think there is something wrong with the trans. The car seems powerless at times, and has had an intermittent problem mostly on the highway at about 60mph that feels like TCC shutter. It feels like the car is jerking when this happens. Another issue I noticed today is that at WOT it will not shift gears. Getting. I changed the fluid when I got the car to chase this problem and got no results. Also re-adjusted the TV cable this week per the FSM. There's no CEL. Any ideas anyone? I'm planning on taking this thing to WF and really don't want to get stuck along the way.

David:

Check the TPS. The TCC unlocks at idle or very low throttle angles. Perhaps 60 is sitting right on the edge, locking and unlocking. Does it do it at 70? If not than this is probably your problem. A bad TPS could also show up as doggy performance if the TCC stays locked too long or the puter is getting the wrong information.

Brother Gord's 91 had the same symptoms and cleared them up with a new TPS and a new EGR. Still not sure if it was one or the other but it runs fine now.

The cable adjustment should improve things, assuming the transmission's throttle valve is indeed going full travel. Remove cable at the throttle body and check for full travel of the cable. Reconnect and re-adjust tension. At WOT the cable should be tight (no slack). If not back off the adjuster (away from throttle body) a couple of clicks at a time till it is.

The reasoning behind this is that when the throttle is at WOT, the transmission throttle valve should be at full travel (just hitting the stop), but no more. This is the primary and only adjustment. They assume if it postiions the valve properly at WOT, the lower settings will also be correct. When you are finished, check to be sure your go pedal does actually go to WOT. With age, these cables do stretch and sometimes need to be adjusted to actually open the engine throttle all the way.

Bill

Check line pressure. WOT shifts are the most difficult for a transmission to do; if it's hurting, then don't WOT shift it! Transmissions that don't shift at WOT often don't have enough line pressure to complete the shift. I'm not familiar with 700R4 shift behavior, but that's what I'd do if it was mine.

FWIW, my wagon doesn't shift very well at WOT so I just let off before it's going to shift and I've been driving it over a year now no problems. I plan to finally diagnose it soon.

sherlock9c1 wrote:

Check line pressure. WOT shifts are the most difficult for a transmission to do; if it's hurting, then don't WOT shift it! Transmissions that don't shift at WOT often don't have enough line pressure to complete the shift. I'm not familiar with 700R4 shift behavior, but that's what I'd do if it was mine.

FWIW, my wagon doesn't shift very well at WOT so I just let off before it's going to shift and I've been driving it over a year now no problems. I plan to finally diagnose it soon.

Agreed. WOT shifts are tough on any tranny. Having said that, if the cable is adjusted correctly, and it is still using the stock throttle valve, the 4-3 shifts should happen at between 50% and 60% throttle, the 3-2 shift at 75%. If you really punch it at speed it will even skip 3rd altogether and slam into 2nd. Not pleasant. Always a good idea to check line pressure before going any further.

Sonnax has a good little valve available that does away with this. Will not downshift at anything less than WOT. Used it on the Locomotive for towing in 3rd. Damn thing would go into 2nd at 1/2 throttle, and at 60 MPH, would wind up the little diesel to its governed RPM. Again not pleasant. The Sonnax valve fixed that.

Bill

Thanks for the input guys. I'll definitly be checking the cable tonight as Bill stated. I don't recall doing it at 70, although I find it hard to keep this car at 70. I almost never push a tranny at WOT, but frustration with this problem left me a bit lead footed and then found that problem. During normal driving it will shift without letting off the gas.

i would think that the governor screen is plugged after all these years,.
the TV cable controlls pressure,. the governor controlls wot shifts,. you can change springs and weights to modify shift times etc,. BUT if the governor screen is plugged partially it will not see enough pressure to overcome the tv valve holding that gear,.basically the governor send s a hydraulic signal so to speak to the valve body to complete the next shift,.

gotta drop the pan and remove both the valve body pieces to clean it out,. the pull the governor to make sure the weights are wore bad,.

This is not a TCC problem,.
as joel said lift your foot up when you want to shift ,. thats easier than the path you need to go down,.

Nick

But would that cause the shudder I get on the highway?

ok,. i re-read you post properly,.
i,d say the trans is old and the pump is weak,. or the filter is plugged,.
(you did put a new filter in when you changed the fluid right?)

low trans pressure will sometimes cause the lockup to slip or engage and re-engage quickly,
it,s a vicious circle,. the converter slips a little raises the rpm slightly, that inceases pump pressure which in turn locks the converter tighter which drops the rpm which reduces pump pressure that makes the converter slip which then raises pressure again (ad infinitum ad nauseum)

Tbi and 700r4,. oof! btdt.

Nick
Definition of a good 700r4:: On its way to the smelter.

I did replace the filter. I'll have to see if I can get my hands on a pressure gauge and see whats going on there as well. What you said about the pump failing does kind of make sense. Any change it could be the TCC solenoid? I figure that would throw a cel being the only electronic part on there though.

95BRMW wrote:

Any change it could be the TCC solenoid? I figure that would throw a cel being the only electronic part on there though.

Not necessarily. The only way it would throw a code is if it was burnt out electrically. The circuit may be fine but the mechanical side may be bad. The valves are cheap and the 700s were bad for TCC solinoids. If you have the pan off, replace it just on spec.

Just reread your shift problem and that sounds like your cable is too tight. Try backing off (toward throttle body) a couple of clicks. Does the tranny shift normally at part throttle? Are the shifts hard or sloppy? If the cable is too loose, the shifts will be too soon and feather into gear (low line pressure). If its too tight, the shifts will be hard and late (high line pressure). A good article to read is at:

http://www.tvmadeez.com/article/index.php
http://www.tvmadeez.com/article/part2.php
http://www.tvmadeez.com/article/part3.php

Check your line pressures first. If they check out than check the TPS and the EGR. If all is well than drop the pan and do the TCC valve while your in there, check the govenor and make sure the filter is properly seated in the valve body. Do the cheap stuff first.

Bill

Just so everyone knows, the pan filter in the 700R4 and 4L60E is only designed to keep bearing chunks from going back into the transmission. It is not good for catching fine stuff. Unfortunately the governor screen Nick mentioned (on the 700R4s) or the EPC solenoid filter screen in the 4L60Es are much finer and act as bypass filters, slowly clogging over time. I have never taken apart a hurt 4L60E that didn't have a clogged and collapsed EPC solenoid filter screen. Some builders even leave those screens out for that reason.

So.... Can these screens be cleaned before a meltdown happens? If so where are they?

Mike

200OZ wrote:

So.... Can these screens be cleaned before a meltdown happens? If so where are they?

Mike

Please do tell!

I made some progress on it last night. Before going out to dinner I pulled the TV cable out a couple clicks and now it shifts at WOT perfectly. I did notice the down shifts are delayed a hair, but nothing too bad. The TCC didn't give me any trouble on the highway at any speed, but it was never a constant issue. I picked up a TCC solenoid and plan to replace it just in case that's the problem.

I have to dig up the receipts I got with the car, but I vaguley remeber the guy I bought the car from saying he had the trans flushed. I didn't see it as much of an issue as it was a few years prior and had a lot of miles on it since (I want to say he had it done abour 40k ago. I'll have to check and see when it was done for sure.

Thanks for the help guys, greatly appreciated!

I'm pretty sure the TCC solenoid is not your issue.

I don't know where the governor screen is on a 700R4/4L60, but on the 4L60E, the EPC solenoid filter screen is in the spacer plate. You have to drop the valvebody to get to it. This is why some builders leave it out.

When you do it, buy a set of valvebody gaskets and get an updated screen from GM for a TrailBlazer SS (get a VIN off Ebay and order the screen that way).

I would also highly recommend the Sonnax 4L60E-HP-01 shift kit while you're in there. That's a truly excellent kit.

95BRMW wrote:

Also re-adjusted the TV cable this week per the FSM.

this info is what i based my advice on,.assuming that your cable was providing full travel and full pressure,.

95BRMW wrote:

Before going out to dinner I pulled the TV cable out a couple clicks and now it shifts at WOT perfectly. I did notice the down shifts are delayed a hair, but nothing too bad. The TCC didn't give me any trouble on the highway at any speed, but it was never a constant issue

Not sure how you adjusted the cable first time according to FSM
you,ve effectively raised the trans pressure,. so the low pressure problems you were having are now obviously not present.

.

95BRMW wrote:

I picked up a TCC solenoid and plan to replace it just in case that's the problem,.
Thanks for the help guys, greatly appreciated!

better buy a couple of muffler clamps too ,. just in case,..
I find it interesting how folks state that they,ve done things according to FSM procedures,. "but it still doesn't work"
then a while later they re-do things and it works, distributors,. 700R4 cables etc,.

meanwhile helpful folks are offering advice,. and diagnosis based on info given,.

It,s good for you that it works better properly now.



Nick

Well I had done it the way the manual states. The way Bill mentioned was to pull it a bit past where it stops when the throttle is at WOT. I'm going to drive it and see how it does, I may end up returning the solendoid if the problem doesn't come back.
BTW, I do have spare muffler clamps, never know when you want to exhaust work at 1AM

Well guys the problem has returned, that fix was short lived. I'm gonna get a gauge on this thing and see what is going on now. All was fine at first, but after about 100 miles on my way to WF, the shudder came back with a vengeance. Now any time and at any speed that the converter locks it shudders. Luckily there's no such thing as a flat road in NY, so with the constant speeding up and braking the TCC didn't have too many chances to lock.

I now have some new symptoms that may or may not be related. Before I left to go home this morning I pulled the wire out of the ECM that controls the TCC lockup (I know, its probably not even remotely good for the tranny but its got to be worse with a sever shudder). I took it out for a ride and within a few miles the CEL came on, but it wasn't for the tcc, it was an O2 failure. I double checked and the wire was the one the FSM said controlled it. Anyways, I drove it home and the TCC did not try to lock. The engine had almost no power and was running rich. You could both smell it and see from how much gas I used. When I got into town I ran my scanner and saw the voltage on the O2 only fluctuated a few mv. I put the wire back in the ECM, pulled the battery to reset the codes, and went on. The TCC was now locking but it still ran like crap and started throwing the light again for the O2. WTF?

This is a 2 month old delco O2, I gotta check the wiring but failing that I'll have to put my old one back in and see what happens. Are these 2 related or just one hell of a coincidence?

I guess the O2 was a hell of a coincidence. I swapped it out with a spare I had in the garage. That problem went away and the engine performs as it did before. Great delco sensor I bought, died just after its 90 day warranty. The shudder is still present and shows no signs of going away. Pressure gauge is on its way as we speak, but in the meantime, anything else I can check?

Ok, got some useful info from gauge (finally). Here are my pressures at idle with everything warm:
Park- 65 PSI
Reverse - 105 PSI
Neutral- 65 PSI
Drive- 65 PSI
3 (regular D)- 65 PSI
2- 140-145 (fluctuates)
1- 125-130 (fluctuates)
All of this is at idle. I noted if I took the TV cable off the TBI the pressure would increase to about 80 PSI in park.

Cruising on the highway, around 1500 RPMS, 60-70 MPH, the pressure is at 70 PSI. When the TCC locks up and the car starts to shudder, it holds steady and maybe moves 1-2 PSI, the needle is pretty much steady. So, is it worth dropping the valve body and checking the screens? Or is my torque converter tired? Maybe a third thing?

I can't really offer a solution Dave, other than to say you definitely are having issues that these cars don't usually have.

My '91 ran flawlessly all the time and the converter wouldn't shudder, but it had a tendency to lock-up at too low a speed, then have to unlock again.

One thing to keep in mind is that engine performance problems or mount issues are magnified when the TCC engages because it's 1-1 now, and also it's putting more of a strain on the engine.

Does the fluid look like it's getting clutch material out of the convertor into it? When you say it shudders, do you mean it shudders when it goes into lock up, or it's vibrating the entire time it's in lock-up?

A friend had a 700R4 that was so worn out it would shudder at each gear change so bad that it made the bed of the truck rattle.

David is it still driveable right now? Because I may have got my dad convinced to buy this from you.

95BRMW wrote:

Ok, got some useful info from gauge (finally). Here are my pressures at idle with everything warm:
Park- 65 PSI
Reverse - 105 PSI
Neutral- 65 PSI
Drive- 65 PSI
3 (regular D)- 65 PSI
2- 140-145 (fluctuates)
1- 125-130 (fluctuates)
All of this is at idle. I noted if I took the TV cable off the TBI the pressure would increase to about 80 PSI in park.

Cruising on the highway, around 1500 RPMS, 60-70 MPH, the pressure is at 70 PSI. When the TCC locks up and the car starts to shudder, it holds steady and maybe moves 1-2 PSI, the needle is pretty much steady. So, is it worth dropping the valve body and checking the screens? Or is my torque converter tired? Maybe a third thing?

Ok re-reading this,. your "shudder" may not be trans at all,. it maybe the ignition is weak, and causing a miss when low rpm lean condition is encountered,.so how are the plugs,wire cap rotor etc,.
you,ve changed the 02,. so it,s trimming it as lean as it can,.which will show up a bad plug,.

Nick

I'll have to pull the plugs out and take a look. I do kind of remember seeing some sort of build up on the front 2 plugs when I changed them when I did the tune up. The plugs, wires cap, rotor and dist. are new. I also swapped in a fairly new coil I got with a box of parts. I can't really tell if the engine is running at full capacity, I never drove a good running l03 wagon before. Going from LT1 cars to this one makes it feel underpowered to begin with.


The car is drivable right now. The shifting issue still exists under heavy load, you have to let off the gas to get it to shift, but it does do it.

This sounds EXACTLY like what I'm dealing with! After five months of chasing down running issues, and finally solving them, I am still left with what I'll describe as a BONK-BONK kind of bucking at light throttle especially on an incline. I believe it is aTCC issue but I don't know enough about it to prove it.
I thought the rough running and bucking were related but they were coincidental as far as I can tell. I will try adjusting the TV to raise the pressure and see what happens. After that I'll probably just live with. After all, it has 228K miles on it!

Thanks for sharing your info!!

I think Nick is definitly on to something here. I took the cruiser into work today for the first time in a week and a half. It idles a bit rough now, and just seems to have no power. I checked out the plugs last night and I found the front plug on each side has some oily black crap on them, and the rest are clean and almost new looking.

Small progress has been made, if you can call it that. Being there's no power here right now, its the perfect time to take a look at the engine in the dark. I noticed a constant blue flash that appears to be between the plastic coil housing and the mounting bracket. It may also be arching slightly between the boot of the wire on the coil to the white wire on the coil, but not sure on that. Spraying with water made it more visible. I'm going to put the original coil back in and see what happens. Before I left work today I unplugged the EGR and capped off the vac line, seemed better as well.

I swapped out the coil to the old one that came with the car. In complete darkness I see a blue arc between the body and the frame of the of the coil. Spraying water on it makes it a bit more visible as well. I also noticed this coil is particularly loud, like a muffled constant arc inside the coil. I guess I have 2 bad coils on my hands, what are the odds?

I realize that this thread is months old, but I'd like to share some ideas and keep the topic going because I have and issue with my tc lockup.....
When you get a shudder as a result of a convertor staying in-appropriately locked, what you are actually experiencing is "lugging" much as you would in a stick-shift car that hasn't been appropriately downshifted upon slowing to a lower speed than the gear is intended for. These wagons are over two tons, and most are equipped with 323 gears and 305 engines, so they ARE gonna lug when locked in too high a gear!
Any tune-up deficiencies will be accentuated when this kind of a load is put to it!
If you believe that such a problem is limited strictly to the tc's failure to appropriately unlock, you can easily add a toggle switch to de-power the TC at any time!
The torque convertor power path travels thru the second brake actuated plunger switch that is mounted above the brake light plunger switch. There are two plugs with two wires each (one pair for cruise control cancel and one pair for TC cancel) The pair that are pink and purple are the TC wires I do know for certain that the brake plunger switch is normally closed (connected) and opens (disconnects) when the brake is pushed. The pink wire is powered with full battery voltage when ignition is energized. I'm not certain if there are any downstream controls between this switch and the trans, although I suspect that the purple wire may go to the MAP sensor and a different color wire then continues to the trans (I have to do some more investigation!) If you pull the plug from this (brake pedal) switch the TC lockup will be disabled, so this is an easy test to see if your "shuddering" stops!

My TC chooses to only lock up during extremely light throttle (or not at all) but I can sometimes lug it down to 40 MPH engaged and dis-engage it by tapping the brake pedal. If I finf a purple wire with full voltage at the trans plug, I'll know that my "failure to lock" problem is inside the trans case!

I've done some further research:
The positive power path to the trans is only interrupted by the brake cancel switch before entering the trans (purple wire) On our wagons, there are two other wires in the same plug which are negative trigger wires operated by the computer to lock the tcc. The white wire directly locks the convertor in any gear and has no other controls on it. The light blue wire, when grounded allows the circuit to be completed when the internal 4th gear pressure switch is pressurized (when it's in 4th gear.)
I have no idea why the direct-lock wire even exists, but I have a hunch it's only for diagnostic purposes.
My blue wire is apparently dead inside the trans case, so i either need a pressure switch or there isnt enough pressure to activate. I think I'll get a good shift kit and deep pan before going inside for a look...

I had to put a new trans in my wagon last week...... The transmission shop wired the TCC without the two ground wires.......The 4th gear pressure switch is a one wire (grounding) switch. This means that any external conrol preventing fourth-gear lockup needs to interrupt the power on the purple wire.
What I noticed almost immediately was that under light throttle, the car is able to proceed into fourth gear before 50 mph (and also locks the convertor), but if you try to accelerate at all, the car "lugs" and will not accelerate.
I installed a toggle switch on the purple wire and the problem is solved now!