Transmission is suddenly acting funky.

[ZeroDarkForce]

I drive a 2013 Ford Fiesta. I recently replaced the CV axle on the driver's side. I also did a transmission drain and fill using the motorcraft dual clutch transmission fluid to refill the transmission. Car has been fine for weeks until a particularly rainy day, yesterday on December 24th in California. The car seemed fine in the morning but as my trip progressed, I started to experience weird shifts on second and third gear. Like I lose power and then I get a high rpm, then it would shutter and go back into regular motion. I also had an issue to where I am stopping and the car would continue rolling for a bit until I really pressed the brakes down. This stopped when I parked for my doctor's appointment and the car was fine again. But tonight, I took the car out to do some work. It was ok at first but maybe and hour or two into my driving, the problems started happen again. The same odd shifting patterns, loss of power during shifting, same rolling further ahead a bit unless I really press the brake pedal down. If someone could give me some advice, i'd gladly appreciate it.

 

[Handy Andy]

It's the water entry part that has me concerned...

• this may be a loose wire connection or when the CV was changed, perhaps a nicked wire in the speed sensor and/or ABS harnesses - crushed wiring can also cause this...due to replacement part or removal of the old one can damage the wires.

Did you disconnect the battery? This High-RPM issue may be due to low power. Not necessarily the voltage - but available current thru a corroded or loose connection point - drops the voltage due to power trying to flow across it. Check the connections of all those sensors in and around that Left axle - especially the speed ones at the steering knuckles where the CV splines meet as well as the seating of the TCM connector.

In essence - go back and review all the spots on the car you worked on - and make sure all those parts are seated, and any signs of corrosion or wet gaskets are a sign of water entry wreaking havoc with your electronics. Even a lose bolt or the castle nut on the axle to hub - can make a vibration show up and the resonation it makes, causes interference with the sensors "listening" for tone off the ABS wheel teeth used by the system - any sort of fault will eventually set a Check Engine Light so start looking as a code-scanner to use for looking thru your DTC connector and start keeping one in the car when this acts up.

You will need to use the scanner to find these codes...and look at the I/M monitors to see in any of them show NOT READY - if you do, that sub system is possibly causing the faulty shifting.

 

[ZeroDarkForce]

It's the water entry part that has me concerned...

• this may be a loose wire connection or when the CV was changed, perhaps a nicked wire in the speed sensor and/or ABS harnesses - crushed wiring can also cause this...due to replacement part or removal of the old one can damage the wires.

Did you disconnect the battery? This High-RPM issue may be due to low power. Not necessarily the voltage - but available current thru a corroded or loose connection point - drops the voltage due to power trying to flow across it. Check the connections of all those sensors in and around that Left axle - especially the speed ones at the steering knuckles where the CV splines meet as well as the seating of the TCM connector.

In essence - go back and review all the spots on the car you worked on - and make sure all those parts are seated, and any signs of corrosion or wet gaskets are a sign of water entry wreaking havoc with your electronics. Even a lose bolt or the castle nut on the axle to hub - can make a vibration show up and the resonation it makes, causes interference with the sensors "listening" for tone off the ABS wheel teeth used by the system - any sort of fault will eventually set a Check Engine Light so start looking as a code-scanner to use for looking thru your DTC connector and start keeping one in the car when this acts up.

You will need to use the scanner to find these codes...and look at the I/M monitors to see in any of them show NOT READY - if you do, that sub system is possibly causing the faulty shifting.

 

[ZeroDarkForce]

So what's the least and worst case scenario? Should I just take it to the dealer or do I keep working on it myself? The way the car behaves, I honestly think some water may have messed up a sensor but, I don't know the dct well enough to really make an estimated guess.