Transmission issue or just bad driving?

Ok so when drivin the car at normal speed 30-40 foot lightly on the gas. it works fine. But then if for no reason I decide to just floor the pedal the RPM shoots up but the speedometer does not go anywhere. However if I go from slightly pressing the pedal at 40, to gradually pressing down then the car speeds up and accelerates as it should. The high RPM with no acceleration thing only happens if I try to go from normal speed light gas to full on pedal to the metal. Now people have said that sound like transmission slipping. Im hoping that not the case for two reasons:

  1. the car accelerates normally if you use the gas like “sane” person and it makes logical sense because if youre going at one speed, you dont instantly go from one speed to max speed just like that. Its a gradual process, you have to build momentum, so Im hoping thats whats happening here.

  2. the car ha had transmission problems before. Its been rebuilt once, it works for awhile because having issues again so then it was replace with a brand new transmission and the computer that controls it had to be replace too. that was 6 months ago. Theres no reason I should be having issues like that after only 6 months right?

Is the Check Engine light on?


nope no lights or errors of any kind (other than the ones that should be on)

At full throttle, the maximum horsepower and torque available are being applied to the transmission which has downshifted to allow the engine to reach maximum HP. So when you floor the gas pedal the RPM should go up but the car should also accelerate briskly. You car doesn’t accelerate briskly. Either your transmission is slipping or you’ve blown the torque convertor or both.

Either way, 6 months from a rebuild, the trans should not be doing this.


thats the thing its not even a rebuild its a brand new transmission

You’d have to be pretty abusive to make it behave like this after only 6 months - way more than just flooring it. I’d talk to whoever installed it. A brand new unit should have some sort of warranty on it.

Still shouldn’t do this!

could it also probably be just a transmission fluid issue?

I suggest you take it back to the shop that installed it. It sounds to me like it’s slipping.

When I floor it at 40 mph on my C4 equipped truck, the transmission will drop to a lower gear and the rpms speed up. That’s normal. But I also notice the vehicle speed is increasing, as well. If the vehicle speed remains the same (or slows) as the rpms continue to increase, that indicates a problem. Watch your speedo carefully next time this happens.

so how about this then. If the transmission is slipping or failing, then would this issue still happen if i gradually press down on the pedal lightly to speed up instead of jut instantly flooring it? Because the car speeds up and accelerates perfectly fine if im going 40 and just lightly pus down on the pedal further if I wanna increase my speed and go faster. If the transmission was slipping wouldnt the issue I posted about above still happen even under that condition?

Don’t you have at least a 12 month warranty on this “new” transmission? Use it.

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No, it won’t because you are applying much less power to the transmission.

Give it up, your “new” trans is slipping. If you installed it yourself, you eat the labor, but at least the transmission should have a warranty.

Not sure if this the correct line from ’ Cool Hand Luke "

Every one to OP We seem to have a communication problem here.

I definitely didnt install it myself. I mean if I had the skills to do that I probably wouldnt need to be here posting this question right? lol

I think what we’re reading is more of and expression of frustration than of communication difficulties.

First, a disclaimer: while I have a good understanding of how automatics work, I’m not as knowledgeable in this area as many.

Now, a few questions for the OP:

Was the torque converter replaced when the replacement of the transmission and TCU (Tranny Control Unit; 'computer") was done?

What type of shop did the work? An independent, a “chain”, a dealer, a “shade tree”?

Here’s what I’m wondering: incorporated into the torque converter assembly is a “lockup clutch” that creates a “hard connection” between the engine output shaft and the transmission input shaft above a low speed. If this lockup clutch isn’t working properly, the engine’s torque can override the lockup clutch and allow the engine to rev at speed without pulling the car along with it.

Not everybody considers the torque converter assembly to be a part of the transmission. I’m wondering of the shop rebuilt and ultimately changed the transmission but reused the same defective torque converter. Twice.

dunno about the torque converter but firestone did the work

All the details should be listed on your copy of the shop order. Hopefully you kept them?
If not, I would not hesitate to ask them. You’ve paid them a load of money and you’re still having problems. You deserve an answer.

Could This Be a manual Transmission???

Slipping clutch.


What is the engine speed when you floor the accelerator? If it is 6000 RPMs or higher the Transmission control module may have selected too low of gear for the vehicle speed or perhaps no gear at all.

If the engine loses power at 3500 RPMs there may be an exhaust restriction or some other engine performance problem.