Thread: Car is stuttering but sure it's tranny

2000 GTP, 128,000 miles. Have owned car 2 1/2 years. Tranny has never been serviced since I owned it (about 28,000 miles). But I've had no issues with transmission until now. Today I drove from Tampa to Ocala with a few stops--it's about 2 hour drive. About an hour into the drive, the car started missing. It "feels" like loose plug wires or something like that. But it's not. It's definitely the transmission. But I've had trannies go on cars before and it's nothing like that. In those cases, the car goes out of gear. In this case, it feels like the start is going to stall. However, when I get on it, it accelerates with no issues. In OD, it will keep "missing" at like 70mph but then it will go away for no reason. Then come back.

In traffic, I put it into 3rd gear to keep it from shifting into OD. Continued to do same thing. But, it's weird. From a stop, it feels like it's shifting 3 times even though it should only shift twice since OD is locked out. And when it shifts into the final gear it shifts hard, feeling the tranny is being dropped onto the ground (I'm sure part of that is my motor mounts aren't good). After that it almost feels like the car can't decide which gear it wants to be in. Then it will be fine for miles with no stuttering. Then it will come back. No weird sounds. Checked tranny fluid. No issues. It's purple and smells fine. I don't know a lot about the trannies in these cars but could it be the torque converter locking and unlocking? Or something like that? Thanks.

The car hasn't been tuned up since I bought it used in Oct. 2010. But I don't believe it's the tb because it revs fine in park and neutral. And under hard acceleration (like 3/4's throttle) it runs fine. It seems only under partial throttle that it has problems. Could it be a sensor? I suppose. Which one? All of them? I just had the crank position sensor changed last October. I re-iterate: the car never goes out of gear with the engine over-revving--which is my experience with bad transmissions. Instead, it feels like it's missing and the car is trying to stall. In addition, when acceleration at 1/4 throttle it feels like the car shifts like 5 times going from 1st to 4th--very strange. At cruising speeds, like 70mph, it's fine but if I take it down to 60mph it starts missing. Throttle position sensor?

Originally Posted by madbeach

Throttle position sensor?

Sensor is very easy to check if you have access to a basic scan tool that can read live data. Slowly depress the throttle and make sure the voltage (or %) reading changes smoothly to WOT, no jumping around or reading 5v or 0v.

Sounds like possible torque converter clutch/solenoid issues. I recommend getting the car scanned for transmission codes. Purple ATF?

I should've added in my original post that the check engine light has come on a few times since this has happened. Since the first occurrence in February, the light has come on maybe 4 times when the stuttering has happened. However, it goes out the next time the car is started.

I appreciate the responses. I'm hoping it's a throttle body or ignition issue but I have big doubts because I think at the core of this problem is shifting between gears, and everything after that is a residual of it.