Transmission Issues - 117k mile 92 EX Wagon Auto

[Shaar]

So before I accept the inevitable transmission replacement, I wanted to run this story by you guys for a second opinion:

Just bought a 92EX Wagon from a colleague with a low 117k original miles. This wagon was serviced by Honda from new to about 98k by the original owner. Shifted fine when it was purchased by the second owner a year and a half ago, then it went downhill suddenly over the past 18 months. This puts me as the new owner as of last week.

Issue as described by previous owner: The car had erratic shift issues where it wouldn't shift into gears properly, so a shop replaced the TCU and shift solenoids. Seemed to work fine after that for a short while. Then it wouldn't shift beyond 1st, and would disengage all gears and engine would just rev up when the accelerator was pressed. Previous owner could pull off the side of the road, shut it off for a bit, start it back up, and drive for a little further before losing all gears and forward movement. Fluid was never replaced during this 1.5 year owner. It was trailer-ed to my house soon after.

What I did: No fault indicators were on, but I pulled the codes anyways. Got a code 15 (NM speed sensor). I then drained transmission fluid and found that it was a burnt orange-red color (no idea if it was ever changed). A lot more fluid than the typical 2.5-3qts came out, so it was probably overfilled. Drain plug had sludgy metal particles built up which i cleaned off. I installed an inline magnetic transmission filter on the return line from the radiator. I topped it off with 3qts of Honda DW1, warmed up the engine, and made sure the level was ok. I then tested resistance across the NM speed sensor and found that it was within spec according to the service manual. Also checked both solenoid assemblies and all 4 solenoids were spot on within resistance parameters. I pulled the 10A ECU fuse in the engine bay for a bit, and replaced it. Closed everything up and took it out for a drive. Went into reverse perfectly, and shifted through all gears smoothly at low throttle around the neighborhood. I gave it a little gas while it was in second gear and it tried to go into 3rd and the revs increased but car didn't push forward. Felt like it didn't engage 3rd. I dropped the RPMs a bit and got it into 1st again and it started having issues shifting up under low throttle.

So give it to me straight - trans is toast and needs to be replaced? I hate to see such a low mileage Honda show this kind of issue. Its still a baby in mileage!

[Shaar]

An update -

Took it for a test drive again tonight around the neighborhood. Shifted through the gears just fine initially. The longer I drove, it began slipping in and out of gear, until finally it would not grab any gears. I was dead in the water and coasted back to my driveway. I shut off the car for about 10 seconds and fired it back up and it went into 1st just fine - enough for me to pull back into the garage.

[Shaar]

I just tested all 4 solenoids by applying 12v to each terminal. All 4 clicked, so I assume these aren't the problem.

Any other ideas?

[Shaar]

Snagged another TCU from the salvage yard even though the one in it is a reman. Plugged it in, and went and drove it. Shifted great through all 4 gears, nice and smoothly. About lap 2 around the neighborhood, and the problem returned. Started slipping back and forth through all gears like it couldn't decide where it should lock up. Then would not grab into gear at all. Shut it off for 10 seconds, started it back up, and back into gear it went....

This is driving me nuts!


Any suggestions?!

[cloudasc]

Check out the link in my signature title DIY: 90-93 TCU fix. Sounds like a bad TCU issue, as you can turn the power off and its like hitting a reset button.

[H311RA151N]

The previous owner would not have happened to make an attempt at purchasing a transmission locally would they?

[deevergote]

It could still be a TCU issue, as they all seem to be failing as they get older. A TCU can be repaired, or you can buy a refurbished one. If changing the TCU made a difference for a short time, it's possible that it is at the heart of the problem.

Is your D4 light throwing any codes?

The transmission itself could have issues, as many people don't understand the importance of changing transmission oil. 10+ years on the same fluid can lead to major problems down the road.

If you can, meet up with someone with a known-good TCU. Borrow it, and see if it changes anything. If all seems good, have one of your TCUs repaired (or do it yourself if you're capable.) If it's not good, then look into rebuilding or replacing the transmission. At this point, a rebuild might end up being the better solution, if you plan on keeping the car for a few more years.

[Shaar]

Sorry guys I didn't get a notification via email that there were replies!

Check out the link in my signature title DIY: 90-93 TCU fix. Sounds like a bad TCU issue, as you can turn the power off and its like hitting a reset button.

Thats what I was thinking, which is why i tried another TCU (unknown if it has problems too). I'll be meeting up with a buddy this week or next to try out his working TCU from his 93 auto. That should at least definitively remove that part from the problem equation.

The previous owner would not have happened to make an attempt at purchasing a transmission locally would they?

I have no idea. The individual I bought it from had not tried to do any repairs on their own with the transmission, so I don't imagine they would have tried to buy one. Where are you located? And do you have a good trans for sale if I happen to need one?

It could still be a TCU issue, as they all seem to be failing as they get older. A TCU can be repaired, or you can buy a refurbished one. If changing the TCU made a difference for a short time, it's possible that it is at the heart of the problem.

Is your D4 light throwing any codes?

The transmission itself could have issues, as many people don't understand the importance of changing transmission oil. 10+ years on the same fluid can lead to major problems down the road.

If you can, meet up with someone with a known-good TCU. Borrow it, and see if it changes anything. If all seems good, have one of your TCUs repaired (or do it yourself if you're capable.) If it's not good, then look into rebuilding or replacing the transmission. At this point, a rebuild might end up being the better solution, if you plan on keeping the car for a few more years.

Will definitely try the TCU again with a known good one. D4 light threw a code 15 which was the NM speed sensor. Tested per the service manual, and it passed. But maybe its covered in metal shavings and can't get a reading... I'll investigate further.

I don't imagine the fluid was changed often, if ever. But hopefully the inline filter and the 3qts I did change did more to help than not..


Between here and the facebook thread, I've got a few more things to look at again:

1) Swap with a KNOWN GOOD TCU.
2) Remove the solenoids and clean them. They click and pass the resistance tests, but maybe they are weak as has been suggested, and are not functioning properly under fluid pressure.
3) Test the throttle position sensor.
4) Coolant temp sensor/thermostat? I read that these provide feedback to the TCU, and if they send readings that the engine is not warmed up that it will not allow it go shift (go into limp mode). Not sure if anyone can back that up, but sounds plausible... My temp gauge rises to maybe 1/4-1/3 of the way up when warmed up.


Thanks again guys. I'll get back at it the next chance I get, and touch base with my findings.

[H311RA151N]

I have no idea. The individual I bought it from had not tried to do any repairs on their own with the transmission, so I don't imagine they would have tried to buy one. Where are you located? And do you have a good trans for sale if I happen to need one?

I'm located between Springfield & Branson. I have an automatic transmission from a 1991 Accord EX. Rebuilt 35,000 miles ago with a new torque converter. I'd take a $100 bill for it.

If you end up needing it send me a PM. I have a truck so I can deliver if need be. I also have a TCU from the same car I'd throw in with it.

[Shaar]

I'm located between Springfield & Branson. I have an automatic transmission from a 1991 Accord EX. Rebuilt 35,000 miles ago with a new torque converter. I'd take a $100 bill for it.

If you end up needing it send me a PM. I have a truck so I can deliver if need be. I also have a TCU from the same car I'd throw in with it.

PM sent.

[H311RA151N]

PM sent.

Back at ya.

I would still rule out the possibility of it being a faulty TCU.

4) Coolant temp sensor/thermostat? I read that these provide feedback to the TCU, and if they send readings that the engine is not warmed up that it will not allow it go shift (go into limp mode). Not sure if anyone can back that up, but sounds plausible... My temp gauge rises to maybe 1/4-1/3 of the way up when warmed up.

It will prevent the torque converter from locking up. Not the issue you seem to be experiencing.

[illinois_erik]

id have started by completely changing out ALL transmission fluid with new stuff..to me besides the TCU possibly being responsible,sounds like it is dirty old fluid. particulates clog up something to the point where it wont shift, then the short time of the pump not running allows the stuff to fall back and unclog whatever it had clogged. A full fluid swap is about 8 quarts. you can do this in your driveway with a bucket and your fresh fluid ready to go. Disconnecting the trans cooler and using the pump in the transmission to evacuate the old fluid out into a bucket while using the other line to take up the new. Your dirty magnet/plug is normal.

[Shaar]

Alright and update for this evening...

I didn't get my hands on the known good TCU yet due to schedule issues. BUT... I did do a little more investigative work on the car today. Here is what I did:

1) Pulled both solenoid packs, cleaned completely including activating the valves while flushing them with cleaner. Cleaned the screens on them also.

2) I was still pulling a code 15 (no indicator light telling me there was a code) even with the salvage yard TCU and a reset. Again it indicated fault related to the NM speed sensor (on the back of the transmission). I went ahead and removed it, saw zero metal shavings or sediment on it. Cleaned it well and reinstalled. Figured I would also yank out the front speed sensor while i was there. It had large chunks of metal shavings on the sensor tip! I cleaned it off and reinstalled.

After completing both of these, I reset the ecu/tcu, and off to a test drive I went.

Observations in the test drive:

Immediately I noticed an improvement in shifting - it felt tighter between shifts. It drove noticeably longer before returning to its regular issue of dropping out of gear. When it did drop out of gear i thought i would try a few things... I stopped on my driveway, in D4, with the brakes on. While idling, i pressed the accelerator slowly and rpms went up, but car started free-falling backwards (driveway is sloped). So I tried something else.... I gave the accelerator a quick 'pulse' where the revs would go up and immediately drop down slightly below the 700rpm-ish idle before balancing out. It went into gear when the rpm's dropped low enough, and I was able to pull into the garage (without shutting the car off like i did before to get it to go in gear).

This leads me to believe it isn't an electrical issue, and probably a fluid pressure issue... potentially the forward pump.

What are your guys' thoughts?

[9tAkord]

I've been reading thru this thread and I only see one constant factor every time that your transmission act up and that is, temperature. As soon as the temperature on the tranny goes up, problems come up. There is a diy on how to manually flush the transmission on a honda. Im not sure if it was here or youtube. Check it out. It might be a good dyi for you to see if the tranny fluid is circulating in the trans or I would at least check on the cooler lines if it is blocked and the cooler inlet/outlet on the radiator.

[Shaar]

I've been reading thru this thread and I only see one constant factor every time that your transmission act up and that is, temperature. As soon as the temperature on the tranny goes up, problems come up. There is a diy on how to manually flush the transmission on a honda. Im not sure if it was here or youtube. Check it out. It might be a good dyi for you to see if the tranny fluid is circulating in the trans or I would at least check on the cooler lines if it is blocked and the cooler inlet/outlet on the radiator.

You're saying that the blockage is temperature related? What would get blocked as the heat increases? And I can get it to go back into gear if i surge the accelerator for a split second. Once the RPM's drop below normal idle and bounce back up, is sortof slops back into gear (if thats a good way of putting it). It doesn't immediately engage, it can shudder a bit while trying to grab the gear.

Right off the bat I installed an inline filter on the return hose from the radiator with the assumption that the fluid was somewhat compromised. I'm afraid i'll spend $100 on Honda DW1 fluid to do the flush and i'll be back to square one. Could dirty fluid be the cause of my symptoms?