Bad TPS? Transmission shifts late and hard.
 

Hi whoever reads this. I have a slight problem. I Just bought a 1995 Honda Civic DX 2dr coupe with 144k miles and Auto Trans.

The Transmission shifts late and slightly hard into third (D3) even on easy acceleration and the same, yet worse, for overdrive (D4). It's not slipping whatsoever. It has good transmission fluid in it. (I'm not sure about the filter) I even put an additive in to stop the hardness but nothing different yet.

What I want to know is if it might have a bad TPS? or even going bad?.. I've seen where the TPS tells the transmission when to shift and how hard to do so in some vehicles but I'm not sure on the Civics, I've never owned one until last Monday. I unplugged it and drove down the road and it shifted the exact same. any help would be greatly appreciated, Thanks in advance!

The engine should run noticeably worse with TPS unplugged. Also CEL will come on. Make sure your CEL works. If CEL is staying on while driving, pull the code.

TPS can be tested with a voltmeter. Connect voltmeter between center wire of sensor (sensor still plugged in) and ground. Turn key on but don't start. Voltage should vary smoothly from about 0.5 volts to 4.5 volts as you move the throttle from closed to wide open (again, engine not running). TPS and MAP plugs can be interchanged, causing lots of problems. The plug having a solid white wire belongs on the MAP sensor.

An automatic 1995 has a mechanical cable from the throttle to the transmission. It will delay shifting when the throttle is wide open. Cable must be attached and properly adjusted. The computer does control engagement of the torque converter lock and I think the shift from 3rd to 4th. Additives in the transmission fluid are definitely not recommended.

ok. the Additive I put in was "Tranny Honey" from Advance Autoparts.
(note to self: don't do again, Check.)

When I unplugged the TPS. absolutely NOTHING changed. didn't run worse, no CEL. I only drove it a mile down the road and back. maybe nothing happened because I didn't drive far or long?

Tomorrow, sometime, I'll check the Cable and test the TPS. I don't feel its critical but it's VERY bothersome.

does the CEL come on for a few seconds when you turn the key to the 1st on position?

I haven't noticed. But I will check that too.

what do I do if my CEL don't work?

If the CEL never lights up even for the bulb test, usually that means someone has taken the bulb out. Pull the cluster and check / install new bulb. On the OBD1 system you pull codes by watching the CEL blink, so it is important to have it working.

just did the test, the bulb does NOT come on at all. I'm about to pull the cluster and see. Maybe someone took it out cause they were tired of seeing it, or didn't want ME to see it when I bought it. this guy really screwed me...

But then again maybe it just blew because its been on so long.

Update: took out the cluster to find, you guessed it, No bulb at all. put the seat belt bulb in the CEL slot and what do ya know, the bulb test works, so I start the engine and let it run and the light doesn't blink, it just stays on.

I figured out the CEL. it's throwing a Cylinder Sensor code and Primary Oxygen Sensor code. (after resetting the ECU)
Before resetting, it had a VSS (Speed sensor) and TPS code. I think the TPS code was when I unplugged it. I dont know about the VSS. I guess I need to drive a little while first.

EDIT: the VSS and TPS are ok. its just the CYP and primary O2 sensor. it runs perfect, so I'm not gonna worry about that too much for now. I fixed the Throttle Control Cable and it shifts wonderfully.. thanks for helping me guys. I'm sure I'll be coming back for more questions later.

Ryan - I have a 2001 Civic with the same issue but I don't understand the acronyms and jargon... I basically know very little about transmissions. If I wanted to go to a mechanic to resolve this, what would I have them do (in layman's terms)? THANKS!

I don't know much about the automatics but I do know that the 2001 is fully electronically controlled-- unlike the OP's 1995 that has a mechanical cable, which turned out to be the cause of his problems. You should start a new thread rather than extend this one.