Mechanics

TRANSMISSION FLARE

1998 Honda Civic • 4 cylinder FWD Automatic • 164,000 miles

I have a 1998 Honda Civic DX with automatic transmission. When I purchased the car it had a shifting flare from 2nd to 3rd gear. The flare wouldn't occur until the transmission had warmed up by driving and then would persist. The one exception was that with a soft exceleration it would flare, but a hard acceleration it wouldn't flare.
Later I discovered that after some trips of about 75 miles or longer the transmission wouldn't flare anymore no matter how I drove it until after I shut the car off and turned it back on then it returned to flaring again.
I recently changed the transmission fluid and checked all the transmission solenoids for resistances within Honda specs and all activate when energized manually.
The car within the last week had gotten warm while driving so after letting it cool down I replaced the thermostat and bled the system of air.
Now the car's temperature guage fluctuates from normal to hot opperating conditions occaisionally and when it is fluctuating the shifting flare is non existent and when the temperature guage remains at normal position the shifting flare occurs between 2nd and 3rd. Also the left blinker started acting up (first it blinked like a bulb was burnt, then it worked fine, then blinked very slowly and is back to working properly) at the same time that the coolant temperature did. The check engine light is also not on.
The cooling fan works properly and when shorted so fan operates manually it will not cool the coolant temp as indicated by the temperature guage on the cluster.
I took the car to a transmission shop and after investigating it they guessed that one of the "pressure switches" were bad (assuming they were referring to the solenoids). I didn't have them do any further work to the vehicle after that.
Avatar
Ihbigred
June 6, 2011.



I've built a gauge that I can have attached the the transmission while driving down the road to test pressures at shift points. I just need to get my car back as my brother has been borrowing it for the past few weeks. Thinking more about this, it's a warm condition as kmomotaro has reiterated. Things that happen when the overall temperature of the car is warmer is that the transmission fluid is thinner, the ECT sensor sends a lower resistance to the ECM, seals soften up and become more pliable. Resistance in wires increases (even if minimal it's still a suspect. Components expand. Just food for thought to maybe provoke an idea?


Tiny
Ihbigred
Mar 15, 2012.
It could be a valve that's leaking at higher temps, due to the thinner trans fluid.


Rivermikerat
Mar 16, 2012.
Kinda what I thought about the CPC valve that I mentioned earlier on. I've heard that the spring can lose a coil or more after use and wondered if that valve in particular could cause this problem only from second to third?


Tiny
Ihbigred
Mar 16, 2012.
That's something that I can't answer. I'm not a transmission specialist. We don't have anyone with that type of in-depth transmission specialist knowledge.


Rivermikerat
Mar 16, 2012.
If the CPC valve is faulty, you would be getting the problem all the time, either cold or at operating temperature.

For transmission, actually the reverse is true of slipping. They tend to slip when cold and works well at operating temperature as pressure losses are reduced when components and seals heats up and expands.

Yours is slipping only when at operating temperature which is the reverse and I would lean towards a sensor fault. Sensors could be sending signals that are interpreted too slowly or slightly out of range and this could be a fault of the PCM or its software.

TPS, ECT, VSS, Linear solenoid, shift solenoids are all possible fault areas.


KHLow2008
Mar 17, 2012.
KHLow2008
That's kind of where I've been leaning the whole time with this car. I haven't been able to take shift pressures yet because of working on a Powerstroke engine miss and working on the other civic I converted over to V-tec. Which is interesting. So I had updated earlier on in this thread that when I finished converting the other civic to V-tec that the shift flare persisted. Well it did, but now it has stopped! The only things I switched were some pin out locations on the wiring harness to match the PCM, the PCM and the Intake manifold. I'm gonna say I may have a combination issue with this car. I had replaced the PCM with other used PCM's but never a known good one. So I'm gonna go find a known good one and try this out. Second reason I believe this is because what KHLow just mentioned above, and secondly I just finished working on a 2000 Accord with delayed shifting and hard shifts and hot soak issues. Swapped out engine and tranny for known good 2002 drivetrain and still had issues. So swapped 2000 PCM with 2002 good unit and wallah! No more shifting or hot soak issues! So I'm gonna bet my money that this is either only a PCM issue or combination PCM and linear solenoid because I've heard that one can knock the other out.


Tiny
Ihbigred
Apr 5, 2012.
For the newer models, updating the PCM might solve the problem.


KHLow2008
Apr 5, 2012.
Yeah, I would agree and I actually contacted Honda about reflashing my PCM and they informed me that these PCM's can not be reflashed. So I guess the only option to update is with a new PCM or known good one. Also I wanted to let kmomotaro and bgorpy know that someone wanted to buy my car regardless of it having this problem. I've ended up selling my problem car and no longer have it at my disposal to do tests on but I am friends with the individual and if I find a good PCM I'm going to swap it out and see what the results are. Please keep this thread updated with what you all do. I'd like to know the fix for this!


Tiny
Ihbigred
May 7, 2012.
I think most of us would really like to know the fix for this. I know I do.


Rivermikerat
May 7, 2012.
Ihbigred, rivermikerat, KHLow2008 - I have still not solved the flaring issue on my 96 ex. I was hoping that ihbigred was going to have an answer. After re-reading through this thread, I was wondering if it was possible to set up a band-aid fix using the potentiometer that was mentioned in ihbigred's earlier posr where the flare issue was eliminated when the coolant sensor was pushed down to 150 ohms. My questions are these: 1 - what would have to be done to duplicate the results in ihbigred's January 27, 2012 posting? 2 - If this was used as a way to resolve the flare issue, would this cause any other problems to be concerned about? I would appreciate any expert opinions. It seems that if I used a potentiometer and changed the resistance of the ECT ( as ihbigred did) after the car warmed up, I could eliminate the flare issue. Again, any expert opins are appreciated!


Tiny
Bgorpy
May 27, 2012.
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