Rick1956

Hi all,

I've got a 2003 LX and its trans seems to have recently started acting strangely. It doesn't have any of the often-discussed transmission problems like grinding or slow shifting fortunately.

Instead, it seems to be up shifting too soon, too early, too often, too far... however you want to explain it.

Basically, it will be driving all fine, then when I take a slow (10-15mph-ish) 90-degree curve that's not a full stop it wants to up-shift all the way to the point of bogging. It sounds like it jumps about 3 gears all at once.

It's acting like there's a vacuum sensor/speed sensor issue that's causing the trans to think it's decelerating downhill or something.

In my opinion, it's messing with my mileage because I have to press the gas down a little farther than I should, plus it's making the trans work too hard.

Thoughts?

ezone

"Grade logic control explained", Honda Service News, Jun 2003. Not sure if just anyone can read this but try this link. http://www.elementownersclub.com/for...ad.php?t=25001

First checks:
Unusual trans noises?
Fluid condition?
CEL on?
"D" light flashing?
Engine and trans codes?
Any other symptoms/problems going on?


I looked up this symptom:
Erratic upshift: 1st to 2nd, 2nd to 3rd, and 3rd to 4th gears
(If this doesn't match, let me know and I'll try something else.)

T/S chart points to wrong/no signals from the countershaft speed sensor. the only way I know to actually read this value is on a GOOD scanner datalist. (If it has not set any related codes.)

Remember here, the sensor doesn't necessarily have to be bad. Around where I live, mice LOVE to eat wires in the engine compartment.



Next on the list after the speed sensor:
Also check for:
- Check the D indicator, and check for loose connectors. Check the output shaft (countershaft) speed sensor installation.

HTH

Rick1956

No other problems that I can recall. No CEL codes, no sounds, no nothing. I'll pay a little more attention, but I don't think the D light has ever done anything either.

The only time it's doing this is coasting around a corner and barely giving it gas. If I'm taking off under regular load conditions the trans shift fine with no lags, noises, or anything.

It wouldn't surprise me if one of those speed sensors went bad because from what I can tell they're simple Hall Effect sensors. My old Dodge Neon went through them (in the form of crankshaft position sensor) every few years.

I'm assuming (now that I have a little bit of an idea where to start looking) that I should give them all a once-over visual check and make sure connections are clean.

If anything else comes to mind I'm all ears!

ezone

Coffee cup in hand......and a slice of pizza.

The D light thing would only indicate transmission related codes have been set and are active.
O0ooh...It might be a normal phenomenon then.

Stab the gas pedal just a wee bit harder to "force the downshift"?
Would be interesting to see what is going on in a PCM/TCM datalist while your complaint is happening.

Before you condemn your car as defective, go locate, drive, and compare to an identical car, see if it is any better or worse.

Electronically shifted transmissions have a habit of not really doing what some people expect then to do, this applied to most manufacturers as they made the transition from hydraulic controls to electronic.
I have had 2 cars of my own that would downshift/upshift rapidly as I go around a corner, feels like a brief "neutral" as I could hear the RPM went up without actually going any faster---then upshift and sort of grab and accelerate. (Always made me want to jump out and see if the trans fluid was low!) This was on the right-hand turn to my own home street, so I get to experience it often.

They all improved performance and feeling steadily over the last couple decades, but I still experience the occasional "whoa--what was that??" feeling on occasion when test driving customer cars. I don't think much of it unless it is actually a complaint. Usually happens on going around the same corner every time.

Mopar had a ton of problems with theirs. (Replaced many. Some OEM parts were bad right out of the box.)

Honda doesn't have the same issues with theirs.
Rare to have a problem with these speed sensors, that's why I mentioned mice.
(In fact, the last one I saw that had a real verified speed sensor problem was on a Pilot that had a bearing inside the trans go bad, it let a gear shaft move and actually physically shave the bottom of the speed sensor off.)

If your speed sensor had a real problem, it should be happening all the time (in my mind) and your complaint would be happening far more frequently than "only after turning a corner".

TPS and MAP have a lot to do with shifting too, but you probably won't find a problem there either......unless you can find something that changes as the car leans or moves through the arc of a turn.

Best thing I can think of after finding an identical car and really verifying there is an actual problem here worthy of chasing.....is to watch gear request vs. actual gear in the transmission datalist during your complaint conditions. Need a great scanner that can access the data. This would be a starting point at least....

Reality:
If the problem isn't readily apparent (screaming obvious) when you take it to a shop, no problem will be found. Few mechanics will spend more than 5 minutes driving the car to attempt to verify your claim, plus 5 more minutes to check for codes (and charge you $100+).

At that point, you might get your wallet flushed (google "wallet flush").

If the issue is truly real, but obscure, YOU demonstrating the problem to the mechanic is best.....IF you can do it in 5 minutes or less. (Time is money here!)
I hate joyriding all over the countryside while some customer drives aimlessly, completely oblivious to the "time=money" thing that is effing up my paycheck.


HTH