Wierd transmission problem

[92saturnsl2]

That last week or so I've been having problems with the Auto transmission on my Frontier.

One morning after a 1300 mi drive across country, the truck started fine. After putting it in drive and going across a parking lot, when I came to the next stop the torque converter appeared locked and caused the engine to stall. When I restarted the truck and put it into drive the truck again stalled.

To get it going, I had to shift into drive under moderate throttle so as to keep the engine running. It did this for a mile or so until the fluid heated up, then appeared to run normally.

The problem reappeared sort of hit-or-miss in that about every other day it acts up, but only when the fluid is cold and goes away after driving for a period of time.

The lockup converter has also been acting erratic, it sometimes goes into lockup too quickly when cold or when going up a hill at 30mph, causing the engine to lug at 1300rpm. Manually shifting into 2nd usually fixes it.

Any ideas what the problem is? No check engine light, transmission seems bulletproof once warmed up. Fluid level is okay, and clear red. It's filled with Mobil 1 Universal ATF.

 

[mikeg5]

nissan trucks have had issues with transmissions from that time period. you may want to google it.

are you checking the fluid level when its hot and RUNNING on a level surface?

 

[unDummy]

Exchange the ATF. If you're lucky, some varnish or buildup might be causing the issue.

But, I doubt that the TC even locks up when cold or in 1st gear. So, you probably have an engine tune issue. Cold idle speed control valve, TPS, wiring corrosion(ground, batteries, alternator, or harness), temp sensors, or something simply like new plugs/fuelfilter/tuneup/BG44k........should be able to fix.

 

[92saturnsl2]

It's definitely the torque converter lockup clutch staying engaged, not an engine tune issue.

When the truck is started cold, it shifts into R or D just fine and begins driving fine. Only when it makes the 1st to 2nd shift, it drops from 2600 rpm right down to 1300 (not normal) and you can feel the lockup, because the engine RPM's won't increase with throttle (as a normal variable lockup AT will allow you to do), but it will still accelerate as if you were lugging a manual at low speed in a high gear.

Once it locks it stays that way even through different gears and coming to a stop you can feel the engine lug as it tries to pull forward against the brake / transmission; Eventually it will stall once I come to a complete stop if I don't put it into neutral or creep forward. It's exactly the same feeling you'd get when stopping a manual in 1st gear while forgetting to press in the clutch.

I just can't figure out why it's doing this and only when it's cold-- it goes away once it's driven a few miles.