Rebuilt Transmission will not go over 65?

[scross1284]

I just had my transmission rebuilt and now it will not go over 65 miles per hour most of the time. The transmission place said it was the computer resetting, but it is still doing it.

It has functioned properly twice over the last few days, but most of the time it does not. Does it depend on the route I take to the interstate?

Does anyone know what might be causing this?

 

[stamp11127]

Monitor the shift points in rpm's for each of the gears. Note the mph/rpm at each shift point. Make sure it is going into overdrive. You can also turn off the overdrive and the rpms will increase when it comes out and goes into gear.

 

[metaldrgn]

You need to explain your problem better. How's it limiting you? What year is your expedition?

 

[scross1284]

2006 Ford Expedition Eddie B 4wd

It is a 2006 Ford Expedition Eddie Bauer 4WD.

I just had the transmission rebuilt. Occasionally it shifts fine, but most of the time it will not accelerate past 65. The RPMs don't go up when you mash the accelerator. It just doesn't do anything. It also does it at lower levels occasionally, like 40 mph. It reminds me of golf carts I've driven that have governors on them.

I took it back to the shop that rebuilt the transmission. They don't think the transmission has any mechanical problems. The computer is not giving any error codes. They don't know why it is doing this.

They have tried driving it warm and cold conditions and put an additive in the transmission fluid, but nothing helps.

 

[stamp11127]

If it is throttle by wire I would suspect the throttle body assembly/tps.

 

[scross1284]

Thanks. I will suggest that.

Would that be something that was effected by the transmission rebuild? They also replaced the converter
.

 

[stamp11127]

I doubt it unless they had to move a harness at the top of the engine.

One thing you can do yourself is to run the engine through most of the gas pedals travel with the engine running and transmission in park. Only do this on a engine that is up to operating temperature. And there isn't a need to go past 4000 rpms in this test.

Slowly depress the pedal while watching the tachometer. If there are any flat spots in the tps you will see it on the tach. The pedal will be moving but the rpms are not increasing. After more pedal travel the rpms may start moving again.

You can also repeat the same procedure while driving. I recommend staying in low gear while doing this. If it is engine related it will show up during one or both of these tests.

Once it gets to 4000 rpms, ease off the gas pedal.

One thing you are looking for is if the engine can speed up without a load on it.

 

[01yellerCobra]

Years ago (when I was a teen) I had a 70 Mustang with a 351W/C4 combo. One night after I dropped my girlfriend off I decided to test out my new intake/cam/carb combo. While letting first gear wind out the car suddenly stopped accelerating and there was a lot of smoke. Enough that I jumped out of the car looking for flames. I got back in and ran the gear selector through all the gears. Everything engaged normally. Thinking I might've gotten lucky I flipped a U-turn and headed home. About the time the trans was supposed to shift into second (under normal driving) the car would decelerate like I had slammed on the brakes. Two days later it was at a trans shop. Turns out I had welded the two parts of the direct drive drum together.

The point of the story, something inside the trans can keep the vehicle from accelerating if it's not right.

 

[stamp11127]

01yellerCobra is correct, if the trans isn't shifting correctly through all of the gears it will only accelerate up to a certain speed, which will be dependant on the gear the trans is in. The op should establish if it is engine related or trans related. Once that is known it will be a little easier to diagnose.

If I'm understanding the op correctly, it has times of no throttle response.

There is a harness that runs from the transmission back up to the pcm that has been an issue if it isn't secured correctly. It will come in contact with the exhaust manifold and eventually short a few circuits.