hey
I have an 86 Iroc-z with a 305 tpi and 700r4. One day last week my car started shifting real soft. TOO SOFT. This from a tranny that used to shift hard every gear. It used to be that i would usualy shift it manuely if i was fallowing trafic because the shifts would almost make it lug. All of a suden one day it started shifting very smooth. Like i'm talking lexus smooth. it's like the torque converter isn't locking up anymore. It used to lock up from second gear through. Now i'm lucky if i can get it to lock up at hwy speeds. Somtimes it will and somtimes it won't lock up.
When I drive now, and accelerate at an average speed, to follow trafic, my rpm will stay at about 2000 and might drop about 100 rpm between gears. The only way i can tell that it's shifting is with the tach because it's too smooth. I can go from complete stop to 100km/h or 62mp/h without the rpm's leaving the 1900-2000 range. No more firm shifts.
it does shift firm at WOT. But that's it!
I changed my fluid and filter. and also adjusted my tv cable. Both with no results.
This was not a gradual problem. It happened all of a sudden. What could it be?what kind of thing would cause this to happen other than the fluide and tv cable?
Selenoid maybe? Valve? Torque converter? or somthing else?
Any help would be great
or even just your two cents!
thanks

Addiction115

 

You seem to be touching on the issue. The TCC. Sounds like you're used to the TCC locking when cruising mildly, thus giving you those tight / boggy shifts. Now you're saying the TCC isn't locking, thus you're feeling the converter buffer your shifts. And also isn't locking during highway/etc cruise? Does that sound like your problem.

If so, trobleshooting the TCC isn't that hard. First thing i would do is hook a wire between the A and F terminals in the ALDL and take it for a quick drive. This will manually lock the TCC. If the TCC doens't lock when it shifts into second then either the TCC has no power, or the solenoid itself is bad.

Next, get under the car with the key on (engine not running), and pull the 4 pin electrical connector from the top of the pan rail (i forget which side it's on, but it's easy to find when you're down there. Check to make sure it has a good connection, and also check the terminals, making sure that one of the outer ones is 12V (i forget which, but i know it's an outer wire)

If no power there, this circuit gets power from a switch on the brake pedal. Check this switch to make sure it is still good.

If there is power there, but the TCC didn't lock in the manual test above, then the solenoid is probably dead (or a mouse ate the ground wire) Swapping the solenoid is gravy, the only PITA is dropping the tranny pan, then it's 2 bolts and slides right out.

If the manual test did work, for some reason your ECM isn't trying to lock the TCC. Likely culprits would be the CTS, or VSS, or even TPS.

 

I dont wanna sound like a moron, but does the CTS (coolant temp. sensor) really have input as to when the TC locks??

 

I bridged the A and F terminals on mine to check for this and I blew the fuse for my guages.... idk why in the world that happened. Maybe my electrical is just messed up... any thoughts on that?

Patrick DeGrosse Jr.

 

Yup, cuz the TCC doesn't lock under a remotely normal schedule until eiether closed loop, or another designated temp, i forget off the top of my head. Trust me. I figured that out a long time ago in my 895 when i was having a problem with it constantly unlocking and locking back up while cruising on level ground. The CTS was coming loosed and shaking around and when it touched it was locked. When it didn't it unlocked.