4th Gear (od) At 30 Mph???

[jeff*k]

i recently picked up an 86 gn that was in terrible shape. the body was shoot and it smoked badly. after 2 months it is ready to drive (thank god)!!!. once the engine warms up it "feels" like its shifting into od at about 25-30 mph. once in this condition a quick tap on the gas produces a strong jerk and then it stumbles untill i can get the speed up to about 45 mph. i do not have a scan tool and can not confirm it is in od, but it sure feels like it.

what do you think??

 

[GNVAIR]

Try unplugging the 4 pronged electrical connector on the driver side of the trans. This will disconnect the tcc solenoid. It sounds like you are feeling the convertor locking up in 3rd gear which would be normal.

 

[Steve Wood]

also set the tv cable as per gnttype.org

 

[timothydog]

Replacing the stock chip with a performance one will most likely make your shift points higher too. At least that was my experience.

 

[GNVAIR]

The only thing a performance chip will possibly do is change the lock up points on the torque convertor. They will not change shift points. Shifts are mechanically controlled on these cars via TV cable/governor/valve body calibrations.

 

[timothydog]

Ah..
Thank you sir for clearing that up..

I'm still learning here myself.

 

[jeff*k]

ok i unplugged the tcc and went for a quick drive. seemed to drive good with the tcc unplugged. i checked ecm for aftermarket chip, nope it says delco. should tcc engauge in 3rd at 30 mph lite throttle?? that seems to be early. it only seems to do this once the car comes up to temp. when its cold i have no problems. faulty tcc switch???

thanks for the replies

 

[timothydog]

As far as the hard 2nd shift. Your TV cable may be pulled back too far. Adjusting the TV cable sets how much line pressure is built up before shifting (correct me if I'm wrong). Having it set too high can really wear your tranny out a lot faster from what I hear. If it is too much for your taste, you can adjust the TV cable in a tooth or two. www.gnttype.org will tell you how to do this.

 

[turbojimmy]

Originally posted by jeff*k
ok i unplugged the tcc and went for a quick drive. seemed to drive good with the tcc unplugged. i checked ecm for aftermarket chip, nope it says delco. should tcc engauge in 3rd at 30 mph lite throttle?? that seems to be early. it only seems to do this once the car comes up to temp. when its cold i have no problems. faulty tcc switch???

thanks for the replies

Yes, definitely faulty TCC switch. The only-when-hot is the giveaway (that and it's okay when it's unplugged).

Classic symptoms of a bad TCC solenoid.

Jim

 

[Black Car]

The factory GM original chip setting was set for lock up
3rd at 23 mph & unlock at 22 mph
4th at 39 mph & unlock at 37 mph

This was after the engine reached a certain temp (app 140*)
The unlock is also controlled by the % of the tps as well as the brake switch as I remember.

You may still have a bad TCC solenoid but I would get a new chip for your combination first. Seeing that you need one anyway.
Just my 2 cents.

Gary

 

[jeff*k]

is there any reason i cant just leave the tcc unplugged?? besides mileage and 1/4 times. i only bought this car to repair and sell.
( i gotta make room for the syclone)!!!

 

[Black Car]

Bruce (WE4) is the man to answer that question.
He is (seems) always in the tranny section.

Gary