Jason E

My uncle, a GM mechanic for nearly 40 years, is now retired and does side work out of his home garage. He's been puttering around with my T/A for about a month now...one thing I asked him to look into is why the torque converter doesn't lock. He pulled the trans pan, and the solenoid (or whatever its called) was still plugged in, but he replaced it with a used one he had on hand anyway. Apparently, years ago people would unplug the solenoids because people didn't like the way engines would lug when the TC would not unlock...some people apparently even swore they got better MPG with it this way, although I cannot see how that would be true.

Anyway, he said this new solenoid "clicked" when it had power supplied to it, meaning it should be functioning. He said if it still doesn't lock once everything is back together, then the torque converter is faulty.

He claims there is no issue at all with driving it like this. I can't help but think it might cause additional transmission issues. Is he right? I hope he is because I really don't feel like having to replace the torque converter in this car. This is the only remaining mechanical issue with it...everything else is great...but it needs paint.

Jason E

Oh and 1 other thing...the car has only 31,000 miles, so its hard to imagine that the torque converter is screwed up...but I guess odder things have happened...

3.4 grape

iTrader: (1)

It won't mess up the trans if it doesn't engage but your fuel economy will go down. I have a 94 camaro and had the same problem, it turned out the throttle position sensor was no good. If the ECM does not receive the correct voltage from the TPS the lockup will not occur. My problem was the voltage was too high, over 4.5 volts.

AlkyIROC

Having a torque converter that locks up means converter slip is reduced to zero. At slower speeds, you get better fuel mileage but won't notice anything different when the engine is operating above the stall speed in high gears such as during highway driving.

For decades, converters never had a lock up feature and they worked fine. Same goes for overdrive gears in a transmission.

Jason E

OK, I understand that... but one question...

While I was driving it out to my uncles, doing 75 on the highway, with the cruise on I noticed that the revs obviously moved up and down more freely than if the TC was locked. Naturally, this would lead to a higher average RPM on the highway.

Wouldn't that affect fuel mileage negatively as well?

Atilla the Fun

Even the best non-lock converters still slip at least 50 rpm on the highway. Lockup converters, when not locked, typically slip 200 rpm all the time, you could see this by lifting off when cruising, and typically slip another 200 rpm at WOT, for a total of about 400 rpm. I find it annoying, and I find it does hurt mpg.
I ran for 2 years with my lockup not locking, so I agree that it's only annoying, nothing worse.
If the check ball and cage came loose from the tip of the input shaft, this might cause the lockup to stop working, but I'm not yet 100% sure about that, it remains just a possibility, to my mind.

Abubaca

iTrader: (3)

I wired a switch up so I could run in "normal mode" or "always unlocked". I found that with the new cam and stall, it now locked TOOOO early, which was great for highway, but no fun around town

Yes, older tranmissions ran unlocked all the time, but they were also designed a little different. Our newer transmissions are designed to be cooled, and the cooler only cycles fluid when the TC is locked. I wish I could tell you exactly what parts were different but I just don't know enough to give you an educated answer. I researched this quite a bit when I wired in that switch, and while I'm not the expert, several people all agreed the trans would run too hot too often, and shorten its life expectancy. Since this was just a weekend warrior, I went ahead with it. I got about 20k miles over about 7 or 8 years on a rebuilt transmission. Trans finally died a few weeks ago. It was worth it to me, but I think in general it was probably a bad idea.