Rep Power: 0

I have a 2001 Civic with the BMXA automatic transmission. At 200k kilometers it was slipping in 4th so I overhauled it. I couldn't find anything obviously "wrong" inside the transmission and some of the fiber clutch plates still had the numbers stamped on them. I put it back in the car and I have reverse and 2nd, but the car won't move in Drive. If I drop the transmission back into 2nd and shift up manually it is fine. Also, if I just get the car moving forward and shift into Drive it will gear up normally shifting through 3rd and into 4th just as it should. The oil pressure ports for the line pressure and the 2nd clutch pack have 120 - 130psi at idle - exactly as the manual states. There is no pressure from the 1st, 3rd or 4th port. The linear and shift solenoids bench test as functional. The TCC solenoid is new. I am getting a PO730 code which is a generic code showing a disparity between the input and output shaft speeds.
I don't believe it could be a mechanical problem because I can manually shift up and all the clutch packs are engaging. If it was an electrical problem it would throw a code. I am pretty sure it's a hydraulic problem, but with the solenoids showing normal and all the passageways and valve body recently cleaned I am not sure where the blockage could be. I am an independent sort by nature and I don't often ask for help but this time I am totally stumped. Any ideas?

 
Rep Power: 133

I agree that it sounds hydraulic to me too. How about a clogged ATF strainer/filter?

 
Rep Power: 0

A clogged filter would definitely do that, but my understanding is that blocked filters are worse after you have been driving for a while. Once you turn off the vehicle and the transmission cools some of the particles blocking the filter fall off and flow improves again. The filter is brand new. I just did a complete overhaul and have only driven around the block 4 times. Where would enough crud have come from to block the filter? Also, I don't like the thought of pulling the transmission and opening up the cases again unless it is absolutely necessary. Took the car out for another test drive last night and I can get the transmission to engage in Drive but I have to rev it up to almost 3k and wait for 5 or 6 seconds.

 
Rep Power: 0

Did you remove the debris from your torque converter? I swapped my BMXA for slxa and found most of the debris in the system was packed in the TC, THE COOLER LINES AND THE ATF COOLER(below radiator). All together, I removed about a FIST sized whad of friction material that looked like black sand& oily mud. My bmxa was f***ed up.

 
Rep Power: 0

I replaced the torque converter and put solvent through the cooler lines then blew them out with compressed air. Then I did a complete change of the fluid pumping it out through the outbound coolant line and continually filling the sump. I have ordered a new shift solenoid just in case that is the problem and it is sticking when it is on the car, even though it bench tests as okay. Bad shift solenoid seems to be one of the most common causes for the P0730 code. The only other possibility is that the filter is blocked. I put in a new one when I rebuilt the unit so I find it hard to believe. Also I have good line pressure and pressure to the 2nd clutch pack. If the filter was blocked I would expect no pressure anywhere. I also really don't want to open that unit up again unless it is absolutely necessary.

 
Rep Power: 0

So did you solve the problem?
Mine is doing the exact same thing 10k miles ago, had it rebuilt, they said it looked new inside. Could not determine what was wrong.
Charged me $1700 for rebuild and now its doing same thing again.
Looking to see what solved your problem.

Thanks

 
Rep Power: 0

I ended up pulling the transmission out again last fall and dismantling it. The only thing I found was a tiny piece off the corner of a paper shop towel jammed between one of the shift valves and the spacer plate. It was tiny - the size of a fingernail clipping, but maybe it was enough to hang up the valve and cause the problem. I live in northern Canada and the car is outside. I will wait until the snow is gone to crawl under the car and put the transmission back in. I am new to overhauling automatic transmissions and one lesson I have learned is never use paper shop towels. Use only cloth, lint free towels that don't leave any fragments behind.
When I overhauled the transmission the first time I couldn't find anything wrong other than the fluid was filthy and the strainer pretty gummed up. Wish I could be of more help.

 
Rep Power: 518

What about the warranty on their work?
Any reputable shop will give a (limited) warranty on their work, and if the trans shop is an ATRA member the warranty may be good nationwide.