slayer_taunu

iTrader: (3)

car is my 00 V6 DD, stock with ~126k
trans fluid is a good color, no SES lights.

every now and then, like once a week, i'd get some really hard 1-2 shifts. mostly seems to happen after driving for a while (like on my last couple miles of my commute, after pulling off the highway). i put the car away for the day and the next morning its fine.

last time i had hard shifting, i had a bad MAF (i was told the trans actually takes the MAF signal into consideration). MAF was replaced a long time ago, and this issue just start re-occuring in the last month-ish. i've tried cleaning the new MAF, and that didn't prevent the issue from still occasionally happening.

any ideas?

Jake's Performance

iTrader: (2)

It could be a broken accumulator spring, or other engine sensor issue. I would put it on a scanner and see what's happening and try to dupicate the complaint.

mrvedit

Righto. Also could be a broken accumulator piston as GM often used plastic ones.
You only need to drop the pan and remove the three bolts which hold the 1-2 accumulator housing. Look for a broken piston or spring. Or just replace it with the very reliable Sonnax pinless accumulator which is only $11:
http://www.transmissionpartsusa.com/...-07799803k.htm

GMRACER13

iTrader: (1)

Check for codes. Probably has a worn TCC regulator valve bore in the valve body. Usually it will have a code 1870.

slayer_taunu

iTrader: (3)

good news! (sorta)... car finally threw the 1870 code today. GM Bulletin says to replace the entire valve body... this thread I found on a truck forum says you can just replace the 'TCC Apply Valve'. anyone have any experience with going that route? it would be awesome to be able to fix it with a $17 part instead of the entire valve body

http://www.gmt400.com/forum/showthread.php?254-P1870

http://www.transmissionpartsusa.com/...-0077805ek.htm

mrvedit

You are on the right path, but that is the wrong valve; that is the TCC valve inside the pump body and rarely goes bad. You need the TCC valve inside the Valve body.

Gosh, no need to replace the entire valve body!

Carlsonauto mentioned to me just yesterday that he is putting together a "Code 1870 Fix kit" with the right valve, a new separator plate, torlon *****, gaskets and instructions.

sjsingle1

iTrader: (1)

i know there are several 1870 fix it solutions.............which is best?

carlsonauto

There are a few different reasons for the 1870 code but the most common is the tcc regulator valve wearing the valvebody bore out and causing leaks and an 1870 slip code. For your application if I was you I would use the fitzall tcc regulator valve. It is fairly simple to install as long as you have general knowledge and can handle removing the valve body.

The fitzall valve eliminates the EC3 strategy (which is GMs fancy term for controlled slippage of the torque converter clutch) and converts it back in to an on or off only tcc no "controlled slippage". There is also a sonnax tcc reg sleeve and valve kit that you can buy that retains the EC3 strategy but it requires a special reamer tool to install it and if you are only doing one transmission its probably not worth purchasing.

Both ways do have their pluses and minuses but both do work.

The fitzall part number you need is A74741Q (only works in 2000 and earlier transmissions. Add -1 to the end for 2001 and later) The sonnax number is 77754-04K and must be used with reamer 77754-R2

If you search the part numbers on ebay you will find everything you need whatever route you want to go. Ted is correct I am in the process of putting together a bunch of different kits that will be available in the near future. I dont have anything quite yet but soon. All the parts are in stock but kits have not been assembled yet. Feel free to pm me if you need anything.

mrvedit

As I understand it, the PWM (or EC3) TCC setup that was introduced around 1995 was designed to soften the TCC engagement/disengagement so that luxury car drivers wouldn't feel it.
I think anyone visiting this forum won't give a bleep about soft TCC engagement and likely would even prefer a firm one that they can feel.
Also, correct me if I am wrong, but some/many/most aftermarket converters are not designed to support EC3; they need the TCC to be on or off, not half-on.

Therefore, I see little reason anyone here would would want to install the fancy/expensive Sonnax valve that requires careful reaming of the valve body.

Therefore, as Carsonauto says, this is the simpler/cheaper TCC valve to repair 1995-2000:
http://www.transmissionpartsusa.com/...-00a74741q.htm

Or if you prefer to buy it on ebay:
http://www.ebay.com/itm/TECHPAK-FITZ...-/181059582004

Also, if you install the Transgo HD2 shift kit, it includes a replacement TCC valve that disables the PWM/EC3 and just makes it on/off. The Sonnax Performance (Shift) kit also provides a replacement on/off valve.

Ted.

sjsingle1

iTrader: (1)

i have often wondered if after market converter suppliers have the clutches set up for or without TCC slip engagement..........YANK or any other sponsors wanna enlighten us?

slayer_taunu

iTrader: (3)

i read that thread on the truck forum a little closer... looks like they are saying the TCC apply valve is the problem, but caused by the regulator valve going bad?

http://www.gmt400.com/forum/showthre...ull=1#post3390

and as far as shift kits go... this is my V6 DD... not my firehawk (which is a manual trans), so i think that might be overkill

carlsonauto

http://www.sonnax.com/system/announc...K_77805E-K.pdf


That valve is intended to fix a worn pump body wihich is a completely different problem. You can read about it in the link I posted above.

sjsingle1

iTrader: (1)

the valve itself does not go bad..........the wear that the valve causes in its bore makes for sloppy clearances......you can ream the bore and put in a new sleeve....and new valve.......or a fix it valve which is over sized and/or is o ringed to hold pressure

GM redesigned this valve assembly several times with the final (?) change in 2001

i got lucky.....my 2000 car had the 2001 valve.......but it got changed out with the valve supplied in the TG kit

carlsonauto

I emailed the guy I deal with at sonnax just to be sure that this valve they refer to and link will not fix or disguise any issues caused by a worn tcc regulator bore. I was pretty sure it wouldnt but I have no experience with the valve that is linked in that forum so I wanted to make sure I wasnt mistaken.

Here is what he replied with,

"You are 100 % correct it will do nothing to correct a condition that is being caused by a worn TCC reg valve."

the "it' he is referring to is the 77805-K valve in the above link