1998 Honda Civic Transmission Flare

Bgorpy, I believe from my research that the linear solenoid is a variable position solenoid controlled by the PCM. My guess is that for some reason there is a bad set of voltages going to it and by me tricking the computer reading a different temperature then that solenoid is being held in a slightly different position. I have looked into building a "Black Box" that would contain the circuitry to bypass the ECT sensor when it got to a specific resistance and then if the car really got "hot" then allow the ECT to take back over, or whenever the car cooled back down the ECT would gain control again. But I have not had time to sit down and go through the circuit theory. One thing I did not like about the potentiometer is that if the car sat and cooled down it had to be removed so the car could start because of fuel/air mixture cold start purposes. Kind of became a nuisance! I wish you lived close so we could try my EX PCM out on your car. Because I continue to stick with it being a PCM issue as I have found it to be the problem on the 98-02 Accord shift problems. I agree with rivermikerat, it could cause issues later on down the line not knowing where that solenoid should be positioned, but that 150 ohms was basically right when I got the shift flaring to stop, so I personally would run it that way until I got a good computer to test out, or every time it came time to shift from 2nd to 3rd just let of the accelerator until it shifted then continue with your acceleration process.

Ihbigred, check out this site it might help.
http://www.hondasuv.com/members/showthread.php?t=57575

Thiang,
I read over the thread you posted and I never checked the TPS for resistances that were out of wack. Not going to rule that out, but why would a car that I worked on with a non-vtec shift flare, but once I changed the PCM to a vtec PCM the flare went away. I'm assuming that was not a TPS issue.

Rivermikerat,
Usually threads stay active that usually have no answers. Looks like it still has yet to be satisfied. Still want to hear from the other people who posted as to what they've done to improve their rides

Yes, I actually sold the problem vehicle. But it was to someone I know so I have access to it if I think of another solution. I may try the TPS out next time I see the car. But, if I come across another one, I'm going to keep chasing it.

I had the same exact problem with my 98 Civic EX 4-door. If you are a purist you won't like my answer, but here's what fixed it. The TPS went bad, so I replaced it with an aftermarket (Dorman). Since the new TPS had bolts that could be loosened, unlike the factory TPS, there is a small range of adjustment on the new TPS. I rotated it slightly so it appears to the computer that the throttle is open slightly more than it really is. That resolved 99 percent of the flaring. It took me several tries to get the adjustment right, and shifts are often at higher RPMs than before, but overall I am much happier!

Interesting that "advancing" the sensor caused the shifting flare to dissolve mostly. Makes me believe even more that it's a PCM issue being that we have been able to resolve the flare by "tricking" the computer of what really is occuring.

Well I agree it is a PCM issue, but what are the chances of getting THAT fixed, since apparently these computers are not reflashable? I program computers for a living, and I'd love to get my hands on the code for this computer, but again what are the chances? My car acted as if there were two separate computer events: one telling the transmission to disengage 2nd gear at about 2600 RPM, and the second telling it to engage 3rd at 3000 RPM, so the flare happened over the 400 RPM range from 2600 to 3000. Under harder but still moderate acceleration, the "disengage 2nd gear" event was delayed until 3000 RPM and there was no flare. So that gave the the idea (after several years!) To fake out the computer by tweaking the TPS to simulate harder acceleration. Strangely enough, it not only raised the RPM for "disengage 2nd" but seemed to lower the RPM for "engage 3rd". Bringing the two together made it all better.

I'm intrigued by the earlier poster who got good results by using a potentiometer to simulate lower resistance (higher coolant temperature) at the ECT sensor. A jumper between the two sensor leads, with the proper resistor, could (I think) change the resistance of the sensor circuit appropriately. Again, it's a way to fake out the computer, but it sounds like it could give cleaner results than the TPS adjustment. Guess I'll have to do some direct-current-physics research to find the proper resistor -- high school physics is pretty far behind me now, so I think it can be done but I don't remember the equations!

Oops, sorry ihbigred, I see the "earlier poster" with the potentiometer was you. I had only skimmed the thread and I missed the problem about cold starts with the potentiometer installed. According to my shop manual, 150 ohms represents a very hot engine, coolant at 212 degrees or higher. Also since the ECT sensor does not respond straight-line to coolant temp, my simple idea of a parallel resistor in the circuit probably would not work -- I still have to think that through. 1/R = 1/R1 + 1/R2.

Rberq,

I'm glad someone else has gone to some steps to try and resolve this! Yes, sadly an in series or paralell resister would not resolve the problem due to cold starts, but! If someone was willing to do some circuitry they could create a cool little black box to change the resistance at operating temperature! I'm an engineer with some minor background in circuitry, but I am elbow deep in grease with my V10 automatic conversion to Cummins diesel w/ manual transmission :) With this box someone could either post how to make it, or make some pocket change on the side. I got the same result seeing the engine was running "hot" by seeing the resistance to temperature curves for the cts sensors.

FourOur,

I went to the website and browsed a bit, but am not sure if you're suggesting we buy some diagnostic tools?

It's sad that some people don't know how to make a good honest living.

Thanks for resolving that KHLow

I have the same issue. Anyone consider a worn out transmission? Your trans is slipping due to wear. Even a Honda wears out.

Thanks for the input and I had considered that, but if you will read through the entire thread you will read that we were able to remove the problem flair in two ways: 1. Trick the car into thinking it is running warmer than actual and, 2. Changing the ecm to a vtec model and doing the "minime" conversion. I've never personally seen a transmission that was worn out act like this. Maybe you can shed some light on which component is worn?