I have an 89 daily driver Civic hatch with an auto tranny to get me to work and back. I can do nearly anything inside of an engine, but when it comes to transmissions, I'm clueless. The problem I have is that when I'm accelerating, sometimes the car will not upshift to a higher gear. It'll stick and the engine will be at a higher RPM than it should be. Backing off on the pedal should make it shift, but no dice. The problem doesnt always happen though. Question is: What controls the shift points on an automatic civic transmission? Can someone point me out to an online manual for these auto trannys?

 

If you're lucky, you just need to adjust the line pressure (the cable going from the throttle body to the auto trans).

With auto trannies, it's adjust the cable, check the fluid level, change the fluid, or rebuild. That's pretty much it.

The Helms is available online as an illegal download.

 

Is there a procedure for adjusting this cable?

Would too much fluid make it act like this?

 

No, it would make the fluid foam up if it hits the rotating assemblies.

I haven't rebuilt a transmission that old, but I think there is a vacuum servo on the outside of the case, with a vacuum line going into it.

Old chevy hydraulic transmission used what is called a TV (Throttle Valve) cable to adjust the pressure used to fight the governor pressure (which opens your 1-2 2-3 shift valves in the D or OD position.)

It's is either a cable, which shouldn't need adjustment (unless it breaks the mounts or cable itself) Or a diaphram on the side of the case with a vacuum line going into it.

If this vacuum line is broken, or the valve itself is ruptured, it will sense full throttle all the time, and shift at a higher speed, even though the car isn't at WOT. This should also make the clutches come on harder because TV pressure also adjusts mainline pressure by way of assisting the pressure regulator valve in the oil pump case. (this could not be a factor if the transmission is old, since the clutches are worn it could make it feel like it once used to, so shift feel would also get harder, but may not be noticable on a old transmission.



after pic:

When TV pressure is at WOT (max TV) it assists the spring to keep it in first gear, until vehicle speed (governor pressure) overcomes the spring and TV pressure, allowing oil to hold the 2nd clutch and shift to 2nd gear. When you are light throttle, there is very little TV pressure and the governor thus shifts the car at a lower rpm and speed.


Easy way to check for diaphram failure is to unplug the vacuum line and plug it so the engine doesn't hunt for an idle, and drive it. There should be no difference if the diaphram is bad. Sometimes ATF can also leak past the diaphram if it ruptures, another sign of failure.

It is mounted externally so it's an in car replacement.

 

You can try and see if the shift solenoids are working good and clean out the screens on them. see if that helps

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 905_Legend &raquo;</TD></TR><TR><TD CLASS="quote">You can try and see if the shift solenoids are working good and clean out the screens on them. see if that helps </TD></TR></TABLE>

No MIL on the D4 light, no solenoid problem, the TCM/PCM would have caught that and threw a code.

 

Update: I was flushed my AC lines and got the solvent on the transmission. I hosed it off a few days ago. Ever since then, I will hear a buzzing or light grinding(sounds similar to something dragging on the tread of a tire in motion) when it shifts from 2nd to 3rd. I also hear it slightly when stopped and moving the shifter from D2 to D3.

This is an old DX model that doesn't have a D4 light on the cluster. It's a red piece of plastic that is on the shifter that will manually point to the D4, D3, D2, P, or R. Would the check engine light come on instead?

Anuone have the Helms manual handy? The FAQ links to the Helms do not show anything for an Auto trans. They only cover manual. The Auto might have it's own book.

 

Make sure your fluid level is good, a ruptured modulator will make the engine suck the transmission fluid into the intake manifold.

Did you check the vacuum modulator on the transmission case to see if it was leaking/ruptured?

It looks like a huge pressure regulator (and thats exactly what it is) with a vacuum line running from the intake manifold to it.

 

I drained out the excess fluid, cleaned the screen and internals of a big solenoid on top of the trans (below the distributor), and played with that cable that connects to the throttle body. None of this has made any difference. I looked around and I don't see anything else attached to the transmission that is connected to the case or to a vaccum line. All of this comes at a bad time with my budget and all.

Would a bad torque converter act like this?

 

The solenoids control the shifting in that transmission, pull the passenger carpet in the footwell back to uncover the ecu, and put the key in the ON (II) position. The light on the case will start blinking like morse code. One long blink is a 10, and one short is a 1, so two long blinks and 4 short would be 24. There will be a longer pause between the codes (like 3 seconds) before starting the next one. Look at this thread to determine what codes you have (ignore the SCS wire, as the light on the ecu does this for you):

https://honda-tech.com/zerothread/1901557

There are a number of things that could cause this, a torque converter would not do that, only thing that could possibly go wrong in the converter is if the stator locked up, and if it did, you would have no power from a stop, or not being able to maintain speeds over 40mph even with the throttle to the floor.