This is my first post here, but I've been watching this forum for a very long time. I have three powerstrokes on the road, and this forum has helped me diagnose and fix a lot of issues. Thanks to all for that.

I have an issue now that I need help with again, and I thought it may be necessary to post in order to explain the specifics for a good diagnosis.

3 weeks ago I replaced the ATF fluid and filter on a 96' F-250 powerstroke with 373K miles. The vehicle got a new transmission at 250K. When refilling the ATF fluid I noticed ATF fluid running over around the pan in what seemed to be several places. Later I realized that I should have had the truck running while I refilled the fluid......too late for that. Anyway I did finish the job and have the fluid to correct level on the stick and there have been no leaks since that day. The tranny functioned normally afterwards for a few weeks and now it has issues:

Doesn't want to shift, slips a bit, slips sometimes in reverse, etc. Problem gets worse as tranny heats up. Has thrown a few codes: PO470 exhaust back pressure sensor circuit malfuntions, and a transmission slip code that I cleared and don't remember specific code.

I'm thinking I caused the problem when I changed the fluid. Maybe I installed the wrong filter, overfilled the pan, or something???.............and maybe hopefully it is something that I can fix myself.

 

is the OD light blinking when any of this happens?

 

Happened one time yesterday but I cleared the code and didn't happen again.

 

it seems like tranny problems on these trucks come without much warning... do you do any heavy towing? or have any performance stuff on the truck?

 

Have done some heavy towing, yes but not much really, and do have performance chip. If my tranny is worn out then I can accept that. If I screwed it up somehow then I can accept that also but just want to know the likely cause of the issues.

 

Is the truck 4x4 or 2x4. The 4x4s need the deep filter so if you put in a 2x4 filter then it could be sucking air. Also where did you get teh filter and did you replace the seal on it? I got to ask this: did you check it on level ground with a hot tranny while running?

 

It's 4x4, and I did install the 4x4 deep filter with new seal. Yes, did check on level ground with hot tranny while running. Have rechecked fluid level several times.

 

check the connecter going into the tranny its next to the exhaust theres a small heat sheild that blocks it. my connecter became loose during a test drive the day i replaced my tranny and the OD light flashed it felt like it was slipping and i had no OD either. Just an idea to check while your under there.

 

thanks fordman

I'll check the connector for obvious problems, but is there something in specific that I should check?

I've got to get this truck back on the road.

 

I disconnected my EBPV connection at the turbo. My truck started throwing the "P0470 exhaust back pressure sensor circuit malfuntions" code. My mechanic asked me if I had an aftermarket exhaust. I do.

He said the EBPV is good at helping keep MPG up in the winter time, but has little to no effect in warmer weather. I reconnected the sensor at the turbo and haven't noticed a big difference in performance. The truck does seem to warm up faster.

If you have an aftermarket exhaust, my mechanic said to not worry about it much.

Is the tranny fluid showing any signs of foaming? If so, you either have too much or too little fluid. It might be worth it to drain the tranny again and refill it properly to rule out any trapped air in the lines or coolers.

 

Check for bent or damaged pins and for corrosion on the pins.

 

the 470 wont have any effect on anything, what did the old fluid look like? how many miles were on it?