My camaros torque converter has went from locking up at around 32mph (any gear, to only locking in 4th. Any ideas on what would cause this ? I thought the ECM controlled lockup?

It's a 'wonderful LG4 305. I wouldn't care but you know how the gas milage for these things are & stalling until 4th is making things worse.

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I was under the impression that the torque converter should only lock up in 4th.

 

I don't know honestly,, this is the 1st OD auto car I've ever owned. Since day 1 from when I bought it it has locked up at 32mph (even in 2nd as long as it was light throttle) but 3rd always locked down in mid shift range (don't know quite how to explain that). 3rd is when it has always locked under normal driving & stay that way into 4th unless (in 3rd) you'd got about 2/3 throttle, then it would unlock then eventually relock.

Forsay the trans would go 500rpm under light throttle in 3rd b4 a shift, about 250 rpm into it the converter would lock, drop rpm, then continue out the 500rpm till shift.

Is my car just a freak of nature or something ? I kind of miss the 3rd gear lockup, aside from the even worse (if poss. for an LG4) gas milage now, it always kind of sounded like it was a 5 speed auto.

[This message has been edited by deadbird (edited August 08, 2001).]

 

Hey man I am curious how you tell when the converter locks and unlocks. I beleive that my car does not lock at all. Not locking the converter makes for faster or slower accleration?

 

86 IROCZ28, the easiest way to tell if it's locking up is to get going in 4th gear (with a warmed up engine) and without letting go of the gas, tap the brake (lightly). If the RPM's increase, the TCC is working.
The TCC is supposed to lock up in 3rd and 4th gear (maybe even 2nd, not sure of that) after heavy acceleration stops.

 

I always knew when mine locked because it felt almost like it was hitting another gear.

So I'm not insane that it should be locking in 3rd (from what Truckman says). I'm guessing it shouldn't but, would a prob w/the trans itself have any effect on this?

I've looked over a wiring diag. for a bird (assuming the camaro has the same getup for an 84 LG4) and saw there is a relay for the TC, but seems ultimatly controlled is controled by the ECM. Guessing the relay works (since I still have lockup).

I posted on the trans board 2 or so weeks ago w/not much responce. Anything would be appreciated, I'm sure this isn't a common problem & maybe there is no answer, but I figure since I don't know squat about an auto trans (just general knowledge), anything from you guys would be helpful.

 

The ECM is programmed to lock up the TC in any gear except 1st. If you were to put your car in second gear an go a reasonable speed for that gear, then you will feel a slight "shift" happen, almost like it's shifting into 3rd. Granted that the TC is locking up as it is supposed to.

If yours is now only locking up in fourth, and it did for sure lock up in 2nd & 3rd before now, then it sounds like it is a problem in the TV cable adjustment. Does the car shift any different, like higher/lower RPM, or does it jerk more when shifting? Or it could be a problem in the ECM or a connection going to the ECM.

Good luck, hope I helped a little

AJ

 

Thanks for that input AJ.

Definatly that car locked up b 4 in 3rd & I was stunned one day to find out it did in second (shortly after I got it). I presumed it was all normal as you've just said.

I've read many post about the TV cable thinking (even tho I had no clue) that that might be the prob. But, as with the post I read, TV cable probs are usually associated w/different shifts.

The shifts in my car are just as they are b 4 the problem, same speed shift as always as to the ratio of my foot on the gas (in general, I pay attn to stupid stuff like that all the time) but speeds & shifts seem to be the same as always, just no more lockup in the lower 3 gears.

As far as the ECM goes, I want to believe that the problem is more siple than that, but, if the converter is locking up, wouldn't that mean the ECM is still getting the info it needs for lockup? Since nothing on this car has really been touched from day one of me owning it, It blows my mind how from one night to the next this happens.

I hate to keep making such long post but, one more question...

I'm assuming the auto trans is like the 5 speeds in having a sensor that lets the ECM know the gear it's in,,, is it poss that ( if an auto has this) this is bad & keep it from thinking it's in the right gear. EG. only 1st to 2nd is registered to the ECM when the car is going 3rd to 4th (kind of like the sensor it out of position)? Maybe I don't have a clue what I'm talking about either,, but I know something is up & it's buggin me. I certainly appreciate any help

[This message has been edited by deadbird (edited August 09, 2001).]

 

No more idea huh ? Well,, that's alright.

One more actual quick question though,
Can you get the converter to lock through the diagnostic connector ? I'll just lock it manually (if that's poss.)

 

See, now you are asking a little more than I can answer for you. I'm sorry. I wish I knew more.

I don't think that the ECM 'knows' what gear you are in as much as it knows the throttle position, RPM, O2, etc. It can calculate all of that to figure out what the RPM:speed ratio is. I don't know how it knows not to lock up th TC in first though.

BTW, the TV cable serves many purposes as far as what the ECM knows. It may not shift differently (I was just looking for the easy diagnosis), but still has an effect on the rest of the transmission operations.

Sorry for not helping more,
AJ

 

Hey bud,
it's alright,, I really appreciate you leeting me pick your brain,, what you say makes sense and for the most part (from reading from others) I get what you are saying about all the other elements. I was aiming along the lines that the ECM "knows" what gear a standard shift tranny is in, maybe there was something in the auto tranny similar as far as gears go. Studying the wiring diag,, the ECM appears to only see 4th as a lockup point (the input on the ECM says '4th gear discrete'). From another assumption, my trans is now acting 'similar' to how it 'should' be locking.

I did find out the the 'F' terminal is the ground for the TC lockup relay, I've got a momentary switch hooked up now to simulate what the TC was doing and have found (since I fig'd I can't do any worse), the brake switch still unlocks the TC even if grounded thru the diatg. connector. The TC will also not lock in 1st no matter what, in 2nd it will lock, after being grounded, in relation to throttle.

I really appreciate all who have read this in means to help & you, AJ, for trying to help. For now, unless this post drags on, I will most likey wire a momentary switch in the handle of my shifter so I can lock during 3rd(like it did) and let off after 4th since the TC locks in 4th.

If anyone has an idea beyond, feel free to add & much thanks to you, AJ, for trying to help to the best of your knowledge on the subject

 

Thanks for the info, I checked to see if my TCC wss locking today and it was. I put it into D and tapped the brake pedal lightly while I was going at about 45 mph and the revs did go up.

I am glad I have finally sorted that out.