Torque Converter Not Locking Much. . .

[vin27]

Hello all,

I've got a 1991 Q45 with about 180K miles.

Transmission has never been rebuilt, although
I moved to AZ a while ago, and just flushed the
Fluid, and added a cooler about 2-3K miles ago.

For the past 10-20K miles, the transmission
acts a bit strange on the high way, more so
in the cold. Mainly just sort of slow on shifts
to 4th, slow to lock up sometimes. .

Now, it almost NEVER locks up on the highway!

While crusing slow, about 40mph, I can
get it to lock up, but not on the highway.

I used to be able to sort of induce it to
lock up, go a steady speed, let off the accelerator,
and it'd lock up.

Now I can rarely get it to lock up on the highway.

So, any ideas on what is wrong, and how easy/cheap
it could be to fix?

What'll happen if I just keep driving it this way?

Do I need a new torque converter?

Should i just wait till the transmission is gone,
and do a full rebuild?

Is it something that can be fixed with out
taking the Transmission out, or apart?

Could I have messed it up by replacing the Fluid?

All the best,
Vin

[goody90q45]

Welcome to NICO.

You could very well have a torque converter gone bad or worn out clutches or a number of things that may require an expensive rebuild. One member just spent over $4000 getting his rebuilt. Money well spent on a well maintained Q.

Before spending that kind of money here's a few cheaper options:
1) Do the transmission self-check as explained in the transmission section (TR) of the FSM. Has the transmission MALFUNTION warning come up in the trip odometer display? I've attached a link to the 95 FSM since it has an index and is easier to use. The self-diagnosis is done sitting in the driver seat with the car in park. Easy stuff.

http://www.nicoclub.com/FSM/Q45/1995_Q45/

2) Did you do a chemical flush when you did the fluid exchange? Was the fluid pretty dirty (brown) when the exchange was done? Had the car been sitting unused for a while when you bought it? All these questions lead up to the chance that internal sensors and solenoids are gummed up with varnish deposits from running dirty fluids. Was the internal filter replaced? If it's clogged it could be low fluid flow causing the problem. I've had good success on 2 of my Q's and Toyota truck with Lubeguard Red (or is it LG Black?) adding 1 oz. per quart of transmission fluid added. Lucas Transmission treatment is also a very good product. Both are about $10/bottle. A lot cheaper than a transmission rebuilt. Either way you'll need to do a drain and fill (3 1/2 qts.) before putting in any additives.

3) Ohm test the external mounted sensors. It's been a while but I believe the turbine sensor, turbine revolution (TR) sensor and inhibitor switch connectors are the 3 in the bundle that is easily accessible (especially on a lift) at the aft end of the transmission at the drive shaft. My 94Q was having shifting issues and a $100 TR sensor replacement solved all its problems. The transmission section of the FSM explains the ohm test procedures. Easy stuff once you're under the car.

[yodawill2000]

On the J transmission the TPS setting controls shift points and lock up speed.

[vin27]

Hello goody90q45,

Thanks for all the info.

1 - I tried the Self Diagnosis, but all it said was AT CHECK,
and I didn't get anything else from the display after following
all the steps, so I guess it's good?

I'm wondering if there is an issue with the throttle sensor?
I'm having idling issues too now, where it's idling up to 1200-1400
RPM at times. I also seem to have the fuel injectors sticking open
while starting the motor cold.

2 - I don't think the fluid was flushed, just most of it replaced,
while the cooler was put in. I've had this car for years, years ago,
it would sit for months at a time, now using it couple times a month.

3 - Haven't got under the car yet!

All the best,
Vin

[RustyBucket]

If you go a few pages past the diagnosis steps in the FSM, you will find what all the results mean.

A/T CHECK does not mean that everything is good, there is a different code for that. Don't worry, though, that result is not an indication of a serious problem. I had my Q do the same thing not too long ago when I ran the check and it turned out I needed to adjust the tension in my throttle cables.

As I recall, A/T CHECK as the result means a problem with one of the following:
- Throttle closed switch
- Throttle open switch
- 1st gear position switch
- Inhibitor switch

I could be missing one item, but those are the basics, focus on checking the first 3 items on that list; none are serious problems. Have a look in the FSM a few pages past the diagnosis procedure for reference on how to check.

[elwesso]

Also note that the trans has to be warmed up in order for the AT CHECK thing to work.. Most people don't do that and its a common reason why people get that message..

When it does lock up, does it seem like it engages properly? You could be looking at a TPS related issue, but if the trans shifts at the right points, then its probably not bad.

[vin27]

When I've checked the Transmission, it was up to operating temp, motor was warm, and I'd driven it at least 10 miles or so.

I'm just guessing it has something to do with a Throttle sensor, I'm having idling problems too! I thought that part of it has to do it with some flooding issue, and or the Fuel Injectors sticking while trying to start it. This has been happening for YEARS, I just floor the throttle and crank till it picks up, then ease off the throttle. If that doesn't start it, I've got a switch now to shut off the Fuel Pump, so I crank it with Open Throttle, once it runs smooth, turn on the fuel pump, starts every time! But the idle speed is off, about 1000 to 1300 at times.

When it does lock up, which it seems to be ok with at low speeds, under 50, it locks fine. On the hiway, it locks up every now and then, and when it does lock up, it's perfect! Through out the years, I've noticed the shifts 2-3 and 3-4 being a little slower then before. Sometimes it feels like it's curring power for a few seconds while the shift completes.

Anyway, what's the best way to check out the Throttle Sensors?

All the best,
Vin

[maxnix]

Lugging engine is not a good operating procedure. Anything over something like 27HP and the lock up is off.

[vin27]

Hello Maxnix,

I'm not sure if I understand, are you saying anything more than 27Hp, the torque converter should be locked up?

Vin