New Transmission MPG Decrease


#1

Back in October I had to get a new transmission for my 1997 Honda Accord. The torque convertor had been stripped to the point where I was having trouble getting into 2nd, much less 3rd and 4th gears.



Since that point my gas mileage has decreased considerably, mainly as a result of my car not shifting as efficiently. On the highway, I used to be able to do 75 and be around 3,000 RPM. Now I’ll be doing 70 at 3,000 RPM. My car used to shift into 4th at about 32/33 MPH, now I have to be going about 37.



Sometimes, though, my car will sort of have three shifts when going into 4th gear. I’ll have the big initial shift, and then two smaller ones and after that, my shift points are where they should be. But that happens infrequently and only after I’ve been driving for a while to the point where my engine has warmed up.



Did I get a bad transmission? Does it just need to be “broken in?” Is something else going on? Thanks!


#2

Maybe someone can post what exactly is a “stripped” torque convertor.


#3

If it was a stall, or locking converter, there is a mechanical connection, but it wouldn’t prevent the shifting at all, it just wouldn’t lock in 4th at speed.


#4

The definition of “new” always helps.
Some consider a boneyard transmission a “new” one.


#5

I’m honestly not sure if it is brand new or refurbished.


#6

I am not a trans expert, but there is no “break in” - there are sometimes some programming issues for the computer and on some vehicles it is self-programming as the vehicle “learns” the driver.

but it sounds like you may be having trouble with the torque converter lockup - which would be a problem with the “new” transmission.

but there could be a host of other things. have you gone back to the shop that did the replacement?


#7

Did the tranny come with the same gear ratios??? Probably did…just a guess.


#8

I haven’t gone back yet. I’m the antithesis of a gearhead so I was hoping to get some information here before I went back. Enough basic ideas, things it could be, things it couldn’t be, so that this company couldn’t shove techno-crap at me and expect me to buy it. I was displeased with them after they forgot to refill the radiator when they replaced it (which I didn’t think they needed to do to replace the transmission but what do I know).


#9

So I took it in and they said there was no problem. They said they took it for an extensive test drive and that it was hitting all the shift points correctly, nor could they find my so-called “three shifts.” Given that it only seems to happen when my engine has warmed up to the point that the temperature gauge is about 40%, and they test drove it on days with the wind chill in the negative teens, that doesn’t surprise me.

They suggested that it might be the Throttle Position Sensor. I find the timing too coincidental to ignore the transmission, but I’m willing to entertain ideas. Is there a way I can check/fix it myself or would I have to take my car in to have it checked? I had my 150k maintenance done during this time and they said there was nothing wrong, but several members of my family have said they don’t think the TPS gets checked during that. Does the TPS even sound like a plausible culprit?


#10

I don’t think the TPS is plausible, but there is a lot I don’t know.

Did they (or have you) verified that the torque converter clutch is operating correctly? A transmission could still hit its shift points, but not have the TCC engaging properly.