Odd ATX shifting

[poissonverte]

Odd thing.. going about 75 on the interstate, cruising on the same road everyday my RPM's are above 3k a bit.. Then sometimes I can feel it kick down to around 2700 where it stays for cruising and were it normally is. The OD is on since if i turn it off it jumps to over 4k.. What would cause this "additional" overdrive? The car is warming up and should be warm by then too... No other drivability issues/problems, but just a curiousity..

 

[NiNeTy Fo SHO]

When it drops to 2700, your torque converter is locking up. The torque converter does not lock up until the transmission temp is like 150 F...the tranny isnt shifting...as you pointed out...

I know mine will not lock up for about 10-15 minutes or so...until the engine has been warm for a few minutes and has had time to warm the tranny.

Its not supposed to lock up when its cold...

 

[poissonverte]

Ahh so the Torque converter is different from the OD.. I never knew that.. guess my ATX cooler is working pretty good.. Thanks!!

 

[Mike93]

Umm...I wouldn't consider this a good thing. Mine is doing the same thing and I've gotten some responses stating this is normal because it's cold out. Not true. I've driven this car for the past 2 years in MN, OH, and NY winters and have put over 35k miles during this time. Not ONCE did it give me a problem with the convertor not locking up in OD...only recently. 135k on mine, the trans shifts badly, now convertor won't lock up...not looking good. Rebuild time is approaching.

I have a thread similar to this from a week ago...check my user name for more info.

 

[HopefulSHO]

As it gets cold it will take longer for the three gallons of tranny fluid to heat up. Especially with really cold air hitting that cooler. Mine takes (generally) at least 10 miles to heat up. Sometimes the torque converter will unlock itself - I'm presuming that's because the fluid was too cold again; because it never did this during 40F+ days.

 

[NiNeTy Fo SHO]

I am with HopefulSHO, mine would lock up instantly when on the highway back in September with 75 degree weather. When it got down to like 40 in the morning, it would take about 2-3 on the highway to get it to lockup. More recently (with 10 degree weather) it was taking about 10 min. or so.

 

[poissonverte]

Hasnt done it all summer/fall.. Only somewhat recently with temps dropping to 30's and today 4 w/out windchill..
Rebuilt about 2 years ago 20k on it..

 

[Mike93]

Consider yourselves lucky. Mine will lock and unlock in any temp. I've been in as cold of temps as 0 degrees and convertor locked right away...been as warm as 40 and it never locked up in my 20 minute highway commute.

 

[NiNeTy Fo SHO]

I would say that your tranny could be on its way out then...sorry to hear.

 

[shoteen95]

mines been weird too...i've driven 30 miles non stop highway and low speed roads and have only had the TC lock up in the last 2 miles of the drive...this was with outside temps below 20 degrees

other time's i've had it lock up about 10 minutes into a drive around town with outside temps at 0..

i hope its a temp sensor, and not my trans going bye bye

P.S. i've seen a lot of these types of comments pop up from us ATX guys as the weathers gotten bitter cold (record cold in some parts of the country)..so maybe we can take comfort that a few people have noticed this, and there's really nothing terribly wrong at all. I havent driven the 95 in weather this cold, i just got it this summer, still i dont remember noticing this situation in the old 93 and it had double the mileage.

 

[Axianator]

Consider yourselves lucky. Mine will lock and unlock in any temp. I've been in as cold of temps as 0 degrees and convertor locked right away...been as warm as 40 and it never locked up in my 20 minute highway commute.

Out of curiosity, Mike, have you checked your codes (my apologies if you answered this Q in your other thread)?

i hope its a temp sensor, and not my trans going bye bye

Actually, shoteen, you just hit the nail on the head.

As "NiNeTy Fo SHO" noted earlier, the EEC will not attempt converter lock until the tranny fluid temperature has reached a certain point. The sensor responsible for relaying these tranny fluid temperature readings is the TFT (tranny fluid temperature) sensor, which is located inside the tranny. If this sensor has failed or is outputting erratic readings back to the EEC, then you will likely experience the often-strange converter behavior that has been previously described in this thread.

 

[stevemainian]

When the TQ converter locks up, dont you basically loose power to the wheels?

 

[SHOZ123]

When the converter locks up there is no slippage at the converter clutch so all the power is going to the wheels.

PermaCool has a couple of oil t-stats PRM 1060 (3/8" fittings) and PRM 1070 (1/2" fittings). Summit and Jegs both have them for around $48 delivered. They are 190F t-stats and are just what you need if you have big coolers.

I'm also thinking about getting one for the PS as it never gets above 150F even at the track at Thunder Hill.