1986 Trans Am, stock automatic transmission, rebuilt under three years ago.

The transmission shifts fine while under normal driving circumstances, but as soon as you gun it the transmission refuses to shift. It hasn't ever done this until recently (today actually).

If I slam the gas off the line, it will speed fine up until about 2500 rpm, when the transmission feels like it seems to be slipping. Anyway, whatever it's doing causes the whole car to jerk and shake. By the time it reaches 3000 rpm, it becomes apparent that something is wrong, and when it should shift it just won't. It'll jerk and shudder at 3000+ rpm and won't shift until i let off the gas and it drops to at least 2500 rpm.

It does the same thing when it shifts from second to third and from third to fourth. If i use the manual option on the shifter, it aggressively shudders, but shifts fine at 3000 rpm when i manually shift to the next gear.

I just checked the transmission fluid the other day when i changed the oil, and, if anything, it has too much transmission fluid, and the color is bright red.

Any and all help would be appreciated - thanks

 

Have you reset the TV cable? Try resetting it correctly and see if that helps.

 

The throttle valve cable seems to be just peachy (see attached pictures), but after reading your suggestion and checking the internet, i read that holley carburetors need a special kickdown cable for the transmission to work correctly with an automatic transmission. I don't know if I have this cable, but I've never had any trouble running the engine all the way up and having it shift fine.

 

I've been working on it all afternoon and i can't narrow it down to anything.

The TV cable is perfectly adjusted and the car shifts fine unless the throttle's completely open, and that car just freaks.

It shakes and sputters, and at one point let out a loud crack (i think a backfire)

PLEASE help me

 

In my experience, if you have a backfire, then you have a wiring/electrical problem. If you really think it backfired, then recheck your firing order, plug wires, dist cap, etc.

Once I had same kinda thing - ran fine unless wide open, then it ran terribly. Thought I had fuel issues. Finally, I found a plug boot that wouldn't hold on the plug enough. To look at it, even touch it, it seemed fine. But to pull it off, it was very easy compared to pulling the other plug boots off. I squeezed the end with pliers, and all my troubles went away.

Another time, I had a bad plug wire. They were all new (like 1 hour since I bought them). At normal driving, everything was OK. At WOT, ran like crap. I found it by testing continuity on all plug wires one at a time - might test that as well.

 

i really appreciate all your help...

what exactly do you mean by plugs? the engine and transmission run fine under normal circumstances, but like you said, once they go WOT, everything goes downhill

 

Spark Plugs.

None of this may solve your tranny issues - you may have seperate problems going on. But will be easier to diagnose tranny if motor runs as it should.

 

Things have gotten way worse!

Now instead of just at the tops of gears, the car slips and shudders throughout the entirety of all the gears. I can only accelerate slightly above idle for fear of hurting the car.

Not only that, but when I do push too hard, from under the hood I hear a bang, or a crack, or a pop... whatever. When the car does this, the rpm drops quickly then returns to normal, but it will make this noise prepeatedly.

I have no idea what the problem could be - HELP ME!

 

How old is your coil and have you adjusted the timing ? These would be good causes for the lack of wot and backfire and popping back through the carb .

 

what's a coil?

and i'm adjusting the timing tomorrow, let you know how it goes

 

The coil is the big thing on top of the dist. cap under the cover .

 

oh okay haha, i'll take a look

thanks!

 

You're welcome .

 

Is the computer working correctly? Is the check engine light on? Do you get any codes. These models will run for a period of time in closed loop. Theydo not supply a 5v signal to the transmission for CONVERTER LOCK-UP! This happens when at speed the converter locks up and makes the tranny direct drive basically. After a period of time with out a working computer the tranny goes. The only cure is one of prevention. These is aftermarket kits that by pass the computer for performance system needs. Havent' seen them for a while but they used to be sold by summit from one of their suppliers. They also prevent high speed shift down from overdrive to 3rd and back and forth.

700 4R tranny

 

wait, explain to me this stuff about computers?

the check engine light has been on since i swapped the engine, i just never got around to making it stay off. but i don't know what codes i'm throwing or how to check.

 

You need to restore your wiring and computer to get the function to return. Buy a Haynes Manual for about $ 20.00 from an auto parts. It has the instructions and all the codes inside. Other options are to replace the tranny with a turbo-hydromatic 350 or do a manual change over. If you have over 350 HP go to a t56 manual. Its more rugged than a t5 manual 5 speed.

 

Here is a tech site that discibes the entire subject and how to bullet proof the 7004r


Happy reading

http://www.montecarloss.com/SSThunder/drivetrain.html

 

If your trans is still wired up the computer will still activate lockup even if the engine isn't connected to the computer thats why your light is on because the engine isn't hooked into the computer . As for your running and popping and such you really need to check the timeing and if the coil is still good .

 

problem solved

to sum it up, the issue was a combination of two problems.

one: the distributor cap was loose, and as soon as i tightened that up the backfiring stopped

two: my valve spring seals had decayed to a point where at least two of my spark plugs were too gummed up to fire at all

after tightening the cap and replacing the seals and plugs, my car runs ten times better

thanks to everyone for their help!

 

You're welcome and two may have been caused by the cap being loose and the seals leaking .