sorry, this is TLDR long winded, but if you have time to kill and i’d rather provide more details than not for someone trying to assist.

1998 honda civic lx, automatic transmission, > 200k miles, otherwise, runs solid

no codes.

when engine is cold, works as should in all gears (P, R, N, D4, D3, 2), but after engine/trans is warmed up it starts this D4 no acceleration problem.

[reproduce steps]
bring car up to temperature
go for a drive (transmission in D4 position)
come to a complete stop
wait at intersection with the brake applied, everything is fine
when the light turns green i let off the brake and press the gas and there’s no acceleration or forward movement. the more i push the gas the more the engine revs go higher, but no driving forward.

[workaround]
under the same condition at an intersection or full stop, put the trans in position 2 and car will accelerate and drive forward. doesn’t work in D3, only 2. then, i can shift up to D3 and finally D4 and clear my shorts at the intersections.



[backstory]
last summer, the car began to have a hard shudder or jerking coming from the front end. this is with the same repro steps above. if i let off the gas and back on gently for the shudder will disappear and car could move forward.
i replaced the engine mounts, as they were shot anyways, which appeared to help initially, but the shudder came back.

OBD2 generic scanner —> no codes.
launch x431 scanner —> no codes.
tried to read codes via 2 pin service connector —> no codes.

tranny fluid is at proper level when warmed up.
tranny fluid ‘flush and fill x3’ method. didn’t help.
tried a tube of “shudder fix”, didn’t help.

spark plugs, coils, dist cap, ignition coil, all fine. but tried old parts that i had saved/lying around. didn’t help.
cleaned and tested all transmission solenoids. no filter clogs. solenoids were able to toggle on and off fine. didn’t help.
replaced all three solenoids (shift, linear, lock-up) with salvage yard parts that i cleaned and tested, still didn’t help.

at some point during all this troubleshooting over a couple months (this is from faded recall) i finally got a P0730 and P0700 codes, but only one time. something like incorrect gear ratio, and the other i think is generic trans failure.
i replaced the sensors (main, counter and vehicle) with salvage yard parts. i’m not familiar with troubleshooting these sensors, but it didn’t help.


[rebuild trans]
i decided to rebuild the transmission. used a rebuild kit that came with o-rings, clutch discs and steels/frictions. the oem clutch discs were in remarkably good shape considering the mileage. some of the steels had good wear, but only the inner most steel had heavy scarring, i replaced them all. all bearings and other parts in the transmission from what little i know appear to be in good condition. i also disassembled and cleaned all the valve bodies (main, reg, lock-up, secondary and servo) springs, valves, etc. i made sure that the valves slid freely up and down the channels. the springs were in good shape and able to spring back without issue.

after reinstalling the trans and starting up the engine there was something seriously wrong while putting it through the gears. grinding noises. i thought that i screwed up something royally on the rebuild.

i took the tranny out and rebuild it AGAIN. didn’t see anything obvious or broken or severe wear marks. well, same problem! gears grinding. but also the new high rev, no acceleration issue begins.

pulled tranny. reinspected transmission parts again; top to bottom. also picked up a reman torque converter. no fix, same issues.

finally, resolved the gear grinding issue after trying several ‘relearn’/reset procedures (e.g.; via x431 launch scanner, removing 7.5A fuse for 10 mins, and the one where you hold down the gas pedal for 35 seconds while in ignition position 2). nutts!

[current status]
at this point, the car will shift in and out of all gears fine, but only move forward in position 2 from a complete stop when car is warmed up.

the torque converter is involved in all gears, but i’ve tried a remanufactured one, the oem original and another one from a junk yard, so it could be at fault, but i doubt it especially since it works in position 2.

the oem honda service manual shows the trans hydraulic flow. it will bypass the 1st gear and clutch components (parts that are housed in the “end cover” housing including 1st clutch, 1st gear, mainshaft, countershaft and park gear stuff) when in position 2, so i guess that’s why it takes off in 2nd.

i’ve started some electrical tests according to the manual on solenoids and ecu, which so far have passed.
i 'played' with the shift cable, wiggling it's position and thinking it could cause the shifter to malfunction or put too much pressure in D4. because it seems a little more forward than i remember, but it shifts in all gears. have to look it over again.

more grinding/testing…

any help appreciated.