Hoping its not my transmission need some insight

[Theguyz28]

About 5 days ago my car started to take a dump on me and wouldn't shift into 3rd and 4th gear. Turns out my cats had collapsed and needed to be replaced. Got that done a few days back and now things are even stranger.

At this point in time my car will only shift into 3rd and 4th gear if I do it manually (car is a 98 z28 automatic with 150,000 miles on it). Some times it will stay in gear and some times it won't. The transmission is fairly new with 30,000 miles on it and I do not dog my car. Right now 80% of the time I have to drive around doing 40 miles an hour staying in 2nd gear.


Any help would be appreciated.

[Dr.Crash]

are you having any other problems? or is it just the tranny

[Theguyz28]

I put enough miles on it to reset the computer and no check engine light has come on. I really don't want it to be the tranny but right now that is all that seems to be the problem. I have just never heard of a tranny being able to shift into and out of gears like this and it is broken.


Could it by any chance be the shifting cellinoid? (not sure how to spell that one)

[Dr.Crash]

im not sure on the cellinoid. But i have heard of people having problems with their alternators and causing their trannys to act up. did this just start or is it something that has gotten worse?

[Theguyz28]

It all started 5 days ago when my cats collapsed and needed to be replaced. Problem is that after they got replaced the problem on kind of fixed. Now I can get to 3rd and 4th gear but only some of the time and its never guaranteed. The alternator isn't very old either as I just replaced it, and an entire wire harness running from it to the battery because they were old, about 9 months ago.

[Dr.Crash]

how is the engine running? have you checked out the 02 sensors? any thing else that has changed?

[Theguyz28]

Engine is running fine, I can still take it to 80 mph in second gear with no problems or hicups what so ever. Other than the whole situation that I have explained nothing else seems to be different or changed. I am baffled by the situation in all.


Where would the 02 sensors be and would that have any effect on something like this?

[Dr.Crash]

Engine is running fine, I can still take it to 80 mph in second gear with no problems or hicups what so ever. Other than the whole situation that I have explained nothing else seems to be different or changed. I am baffled by the situation in all.


Where would the 02 sensors be and would that have any effect on something like this?

if your engine is running ok then its not the 02 sensors. when was the last time you serviced your tranny? how is the fluid level?

[Theguyz28]

if your engine is running ok then its not the 02 sensors. when was the last time you serviced your tranny? how is the fluid level?

Haven't had the tranny serviced since I put it in. Fluid level is perfect and the fluid looks fine (not burned up or any discoloration).

Also with the car "off" rotate the throttle at the TB. Make sure the kick down cam is'nt hanging. Best to have some one work the throttle from inside the car and you just watch what the TB is doing. Sometimes just moving it by hand can be inconclussive.(spell?)

Most of this is foreign to me. What exactly would the kick down cam look like? How do I rotate the throttle at the TB?

Thanks for the input so far!

[Theguyz28]

Have someone else get into the car. With the car off, have them press the gas peddle.
As they do this look to see what's moving on the engine. You will notice movement at the throttle body these are the throttle and kick down cams which are controlled by the gas peddle. This is where the throttle cable and the kick down cable are usually located and/or connected. Usually there is two cams which are spring loaded. One cam for throttle and one for the kick down. They should move together when the gas peddle is pressed to the floor. They should also return to the same possition together aswell. If one doe'nt move or sticks after being rotated this is bad. 2) Under your car with it safely jacked up look for the wire harness that plugs into your trany. Inspect the plug/s and the wires for damage. Such as broken connections, bare wires, melting. Any damage here is bad also. Inspect where the cable for the kick down enters the trany, look for any damage aswell like on the wire harness. if you cant find or see any obvious problems then continue on. 3) warm up the car to opperating temp. Pull the trany dip stick with the engine is running in park. Check the level should read "full hot" or be within the crosshatch pattern on the dip stick with the trany warmed to temp. Pulling the trany dip stick without the engine running and trany warmed will not give you the proper operating range fluid level. If needed add fluid with the engine still running till it reads proper level. If all else fails take it to a shop and have the trany gone over and tested. Hope this helps good luck!

I appreciate all the advice you have given me, unfortunately all of that stuff checks out with no problems .

I think the next step is to take it in and get the tranny serviced and see what the mechanic tells me. I sure hope I don't need a new tranny after only having put 35,000 miles on this new one.


Thanks all

[Dr.Crash]

I appreciate all the advice you have given me, unfortunately all of that stuff checks out with no problems .

I think the next step is to take it in and get the tranny serviced and see what the mechanic tells me. I sure hope I don't need a new tranny after only having put 35,000 miles on this new one.


Thanks all

good luck!!!

[shady milkman]

how do you know your tranny fluid is perfect ?? if you are off just by as little as 1/4 of a quart on both sides then your tranny will get f'ed real bad real quick.

[SINISTER-TA]

Just guessin'. Check your kick down cable for damage and/or disconnected. Check the fluid while running and warm too. Have the trany flushed and checked for programing.
Only things I can think of right now. Good luck with it though..

PS. check the trany wire harness for damage too.

About 5 days ago my car started to take a dump on me and wouldn't shift into 3rd and 4th gear. Turns out my cats had collapsed and needed to be replaced. Got that done a few days back and now things are even stranger.

At this point in time my car will only shift into 3rd and 4th gear if I do it manually (car is a 98 z28 automatic with 150,000 miles on it). Some times it will stay in gear and some times it won't. The transmission is fairly new with 30,000 miles on it and I do not dog my car. Right now 80% of the time I have to drive around doing 40 miles an hour staying in 2nd gear.


Any help would be appreciated.

Check the mount for the shift cable on the driver side of the tranny. It's held in place with two pan bolts. Make sure this wasn't bent or damaged by whoever replaced your cats. Also, the factory shift cable can be set in two different positions, One position is for a car that was equipped with the 3.23 gear (GU5) and the other with 2.73's. I don't know which one you have but you can easily tell by looking at your shifter. If the shifter has a gear selection of 1-2-3-D, then you have 3.23's, the "rear axle performance option (GU5 code). If your gear selector has 2-3-D, the car has the standard 2.73's. This is if your car is still stock geared and hasn't been changed. If that cable has been set wrong the the tranny will not properly respond to what position your shifter is in.

I would start by checking that first.

[shady milkman]

Check the mount for the shift cable on the driver side of the tranny. It's held in place with two pan bolts. Make sure this wasn't bent or damaged by whoever replaced your cats. Also, the factory shift cable can be set in two different positions, One position is for a car that was equipped with the 3.23 gear (GU4) and the other with 2.73's. I don't know which one you have but you can easily tell by looking at your shifter. If the shifter has a gear selection of 1-2-D-OD, then you have 3.23's, the "rear axle performance option (GU4 code). If your gear selector has 2-D-OD, the car has the standard 2.73's. This is if your car is still stock geared and hasn't been changed. If that cable has been set wrong the the tranny will not properly respond to what position your shifter is in.

I would start by checking that first.

i am gu4 and mine go 1-2-3-D-n-r-p..maybe the r and n are revesed...but its not that like how you described

[shady milkman]

nice edit..i was going to quote and say...damn sinister that was rough

[Smittro]

i am gu4 and mine go 1-2-3-D-n-r-p..maybe the r and n are revesed...but its not that like how you described

Thats because no GM f-bodies(at least none that I've ever heard of) have only a (2-d-od) gear selection on the console.

[shady milkman]

Thats because no f-bodies(at least none that I've ever heard of) have a 2-d-od gear selection on the console.

well i mean..the D is our 3 ...but we have a 1 selector...but mine says 3 and 1

[Smittro]

Check the mount for the shift cable on the driver side of the tranny. It's held in place with two pan bolts. Make sure this wasn't bent or damaged by whoever replaced your cats. Also, the factory shift cable can be set in two different positions, One position is for a car that was equipped with the 3.23 gear (GU4) and the other with 2.73's. I don't know which one you have but you can easily tell by looking at your shifter. If the shifter has a gear selection of 1-2-D-OD, then you have 3.23's, the "rear axle performance option (GU4 code). If your gear selector has 2-D-OD, the car has the standard 2.73's. This is if your car is still stock geared and hasn't been changed. If that cable has been set wrong the the tranny will not properly respond to what position your shifter is in.

I would start by checking that first.

Do you even know that the automatics can be reprogramed? Or what a kick down cable does or is? Mine is drive by wire and dont have one, yours probably is too. However theirs is'nt.

[Smittro]

well i mean..the D is our 3 ...but we have a 1 selector...but mine says 3 and 1

I got ya, I meant they all have at least 4 foward gears on the console..

[SINISTER-TA]

nice edit..i was going to quote and say...damn sinister that was rough

Yeah...I decide that I better be nice.