1999 Q45 transmission issue problem-maybe?

[bullittandy]

So, on my 99 Salvage title Q45 with 175K the transmission has developed a "problem." First, service hx:-no hx before 135K, -no documented hx of transmission service from 135K-165K but fluid was red when changed.-I got the car at 165K after it had sat for one year-I did a pan fluid exchange-maybe 4-5 times? draining 3-4 quarts each time and curently has Valvoline fluid with Red lubegard.-no filter change

Car shifts fine (has 1-2 hesitation that appears common). "problem" occurs when i STAND on the brakes, the car appears to not downshift, lugging and slightly stalling the engine. The engine doesn't stall but you can feel it in the car and see it on the tach. Expereince is similar to leaving a stick shift car in, say, 3rd gear while rolling to stop.

Its not really a problem but feels weird-any ideas? Coverter not unlocking? other ideas?

[BadQ45t]

that sounds like the converter not locking for sure. I went through an issue just like this with an old Mitusbushi my wife bought new, it was the converter finally....with the car you have I'd just live with it until it dies.

[Skibane]

Quote »Converter not unlocking?[/quote]Almost sounds like it's not unlocking as soon as it should. If it didn't unlock at all, the engine would stall.

Does it still do the same thing when you make a stop with the overdrive lockout switch engaged? How about when the shift lever is in 1st gear?

[bullittandy]

Is the converter electronic, mechanical?

I will try shifting it out oof OD and trying different gear positions this morning to see what happens.

[MinisterofDOOM]

Is the converter electronic, mechanical?

The lockup clutch is mechanical, but hydraulically actuated by electronics. So the problem could be any of the 3. FSM recommends checking the closed throttle position sensor. I'd start with that and the lockup clutch solenoid.

Almost sounds like it's not unlocking as soon as it should. If it didn't unlock at all, the engine would stall.

That's kind of my line of thought as well. I wonder if maybe it's just not releasing all the way...meaning maybe the line pressure isn't being fully released so it's remaining partially engaged. How does the car behave while stopped? Does the engine still struggle or does it idle okay once you get stopped or below a certain speed? Usually torque converters unlock below about 45mph, so if it does feel like it eventually unlocks, that at least tells us a little something. The converter should also NEVER lock up at all at any speed in 1st or 2nd gear, which goes along with Skibane's post.