torque converter lockup - locks, unlocks, locks...

[kis86]

Deer season is here! Going up north to hunt...decided to get an oil change before taking the 4-hour trip. Got out of town, onto the interstate and everything seemed fine. Then the torque converter unlocked, rpms went up. Then it locked up again, rpms down. It did this every 10-15 minutes the whole way.

Why would the car do this?

[Hocrest]

Do you have an external tranny cooler? Is it bypassing the stock cooler? In series? In parallel?

If the fluid get's below 100* it will unlock the TC.

[kis86]

hmm yes there is a cooler installed, not sure how it's hooked up. I'll have to check. Is there any way to set it up so it's not over cooling then?

[Hocrest]

Do you have a temp gauge? Last year I covered mine with a sheet of plastic to block airflow. Without a gauge, I wouldn't recomend covering the cooler. You could undercool and overheat the fluid...

This year I replumbed it to also flow through the stock cooler in the rad to heat it back up.

[kis86]

Thanks Dave will try that, have to get a gauge.

What do you think is the best cooler setup? (bypassing the stock cooler, in series, in parallel)

[gstape]

I would bet it is a bad signal from your throttle positions sensor. Mine did the same thing for a while and that was the problem. I think some people have had success cleaning and or adjusting them. I replaced mine.

[b3lha]

Definitely worth checking the throttle position sensor. The TPS decides whether to lock or unlock based on your speed and throttle position. There is a graph showing how this works here:
http://www.subaru-svx.net/forum/show...7&postcount=16

[dennyo]

Originally Posted by b3lha

Definitely worth checking the throttle position sensor. The TPS decides whether to lock or unlock based on your speed and throttle position. There is a graph showing how this works here:
http://www.subaru-svx.net/forum/show...7&postcount=16

will using alot of throttle body cleaner have any effect on tps output.i took my tb off and gave it a good cleaning last spring and now i'm getting similar symptoms. thanks dennis

[Crazy_pilot]

It shouldn't unless you blasted it liberally all over the throttle body. The TPS is mounted on the outside of the TB, and takes readings from an extension of the throttle plate rod, so it would be hard to get anything on it from inside the throttle body.

[Hondasucks]

Originally Posted by kis86

Deer season is here!

SO NOT FAIR! Deer season ended here on Friday and I didn't get anything but a leaky head gasket in my Legacy I was SO looking forward to a freezer full of venison too

[dcarrb]

I had one doing the same sort of thing, but constantly rather than every few minutes, and within a narrow speed/RPM range. Only on the freeway was this a problem. New TPS was the cure.

dcb

[Maxo]

Originally Posted by dcarrb

I had one doing the same sort of thing, but constantly rather than every few minutes, and within a narrow speed/RPM range. Only on the freeway was this a problem. New TPS was the cure.

dcb

Very interesting... actually the TC would unlock around every 2-5min and I was cruising down the interstate at about 75mph. When it unlocked it was very subtle and rpms would only increase by about 250. What's the price tag on a new tps?

Originally Posted by Hondasucks

SO NOT FAIR! Deer season ended here on Friday and I didn't get anything but a leaky head gasket in my Legacy I was SO looking forward to a freezer full of venison too

I didn't get anything either... next weekend though if it's brown it's down

[Hondasucks]

New TPS is ~$300... I'd check the cooler, it might be over cooling and that might be your issue, try plumbing it back through just the stock cooler in the radiator and see if that makes the problem go away. You could also maybe get some sort of thermostatic bypass valve that will run the fluid through the additional cooler if the temperature gets above a certain temp.

Originally Posted by Maxo

I didn't get anything either... next weekend though if it's brown it's down

Yeah, but we didn't even SEE anything in 4 weekends except lots of tracks, lots of poop, a bear, and a couple of does.

[dcarrb]

Originally Posted by Maxo

Very interesting... actually the TC would unlock around every 2-5min and I was cruising down the interstate at about 75mph. When it unlocked it was very subtle and rpms would only increase by about 250. What's the price tag on a new tps?

I'd think you should be able to hold the throttle in one spot and get it to act up continuously if it's the TPS. I only noticed my problem on the freeway because otherwise I was able to manipulate the gas to stay out of the "bad" spot.

Makes sense to try re-plumbing the ATF cooler before springing for a TPS. If you do decide to buy, do a search because I'm thinking I paid in the neighborhood of $185 from either Advance Auto Parts or Autozone; there's a thread with my post about that here someplace. I do remember that the part was identical to what I took off the car, right down to the manufacturer's serial number molded into the plastic.

dcb

[Maxo]

Are there any other symptoms that could indicate a bad TPS? They seem a bit spendy and I definitely don't want to rush out and buy one just yet. The car also has a double hesitation at low rpm, like when making RH turns or just starting from a stop. The hesitation is very pronounced when the engine is cold. Could that be the result of a bad TPS also? The car is a '92 and doesn't have the ecu bead to crush. Just out of curiosity, does the SVX share the same TPS with other Subaru's?

I do have a transmission cooler, it's currently sitting on a shelf in my garage... I think she was thinking of the aftermarket transmission filter I installed.