93 Accord w/ 145K miles. Shifts in and out of overdrive at about 70 mph. Specifically, it'll shift into OD when climbing a slight hill, then shift out when going down a hill. 1 mechanic sugguested flush and fill, another said to drain and fill. 1 tranny shop said it was interior problem and needed tear down. Other tranny shop said it was electrical (computer to tranny), but they couldn't find problem as no codes were registered in CPU. No, haven't taken to Honda (don't trust them - other car/other problem). Problem has been present for over a year and affecting gas mileage (25mph currently). Any help/direction?

Rob

Welcome to the forum!
I hate to see zero replies!
So did you replace fluid for starters? This is quite a simple procedure.

Sam

Still driving it. Trying not to waste $, don't know to flush or just drain an fill. Ended up calling Honda Dealer and they said to drain & fill, but will take several drain and fills to get all new fluid throughout the tranny. Will probably just do several drain and fills and see if that will fix the problem. Don't know what you mean by "starters"?

How much RPM change are you seeing on the "shift"? Sure it's not the Torque Convertor locking and unloocking? That's more common that overdrive working contrary to design....

I used to have an Accord that would kick up and down a few hundred RPM when climbing a moderate hill. No one (on this forum or elsewhere) had a clue. I ignored it and it never got worse. Eventually I decided it wasn't worth worrying about.
Specifically, it'll shift into OD when climbing a slight hill, then shift out when going down a hill.
That sounds like the OPPOSITE of what it's doing. And then it's behavior is probably normal. (25mpg isn't all that awful, depending where and how you drive. There are a lot of other reasons for poor mpg.)

Assuming that the motor isn't just getting tired and neccessitating a lot of OD in-out due to you having to step down on the gas harder than normal to climb a hill, and assuming clean fluid, etc, next thing I'd do (if it was mine) would be to disable the torque convertor control and see if that clears the problem...a lotta people feel TC lockup jumping in and out and misread it as OD shifting...but the RPM range is smaller, about 100 RPM vs 300 or so for an OD shift...a TC lockup solenoid job isn't cheap, but still better than rebuilding a tranny.

Normal operation: Above 40 mph or so and in OD, cruising at steady speed on level ground, the TC will lock and lower RPM slightly. At the first sign of additional load on the driveline (a hill, or a request for acceleration), the TC will unlock, and RPMs will jump up a bit, and a slight bump is felt by real observant drivers as this happens. If unlocking the TC isn't sufficient to keep the motor from bogging, the trans will then make a downshift to the next range, D3, and the motor's additional RPMs will overcome the load...

Transhift cable adjustment issues are known for odd shifting patterns and hyperactive OD shifting...in GM cars we call that "search and lurch" as they keep hunting in and out of OD because the cable isn't adjusted right...it's a very easy adjustment to make, but make sure you get the correct procedure for your EXACT engine and trans before attempting it, or you may make it worse, and always record exactly how much adjustment you've made so if nothing else, you can return it back to where it was...

Could be an issue with the D3-OD upshift solenoid being weak and bleeding pressure or something too, make sure the wiring harnesses to the tranny are tight, clean and undamaged....if you don't see any external reason for it, maybe try a fluid change with a quart of K+W Transeal or Seafoam Tranny treatment, both are great for cleaning up stcky solenoids and valve bodies...

It should be either electrical or vacuum leak. Mechanically your tranny should still be good, just the stuff that controls it messed up.

Don't neglect the adjustments between the Throttle Control Cable to the transmission. I had similar up & down RPMs. Thought it was the Torque Lock Solenoid. Read that the cable should have very little play. I did adjustment to tighten the cable. I've better fuel mileage, the engine doesn't exhibit those 100-300 rpm shifts at unusual times, and it doesn't 'hunt' for gears as it was want to do.

When the overdrive or torque converter kicks out, it goes up about 300 RPM's. When it was tested by tranny shop, they claim it did the same in other gears, but I've never noticed that so much as I mostly do highway driving. I'm still unsure whether to do a drain and fill or a flush and fill for my first attempt to fix this? Many have said the flush with cause debri to come lose and ruin the tranny, while others say it's the only way to get it clean. Thanks.

Thanks a ton. I changed the fluid (didn't see any change) then checked the throttle control cable and found it a little loose. Made the adjustment and it corrected the problem immediately. THANKS AGAIN TO EVERYONE. YOU SAVED ME HUNDREDS OF $$$.

MUST use Honda fluid...correct?

No, didn't use "Honda" fluid. But no more than 3 days after my last post the problem resurfaced again. The throttle cable wasn't loose, so it's something else. The problem comes and goes.......and I still haven't found out the cause.

removed both computers engine & trans wd-40 all connections...dried with qtip. hooked everything back...problem GONE?? Tells me bad connection at one point.