bprzybyl

iTrader: (3)

Over the past year I've been trying to get my project car running which has a 5.3l from a 2005 silverado and 4l60e from a 2003 avalanche. Here's what happens-

Start car, shift into drive, RPMs raise like normal...

Start moving, somewhat harsh shift into 2nd...

Once in second, hard acceleration will send the RPMs to redline.

Anywhere over 20mph, attempting to accelerate will only send RPMs to redline.

By flooring it quickly and then letting off and flooring it again, I can sometimes get back into 2nd, at which point I can accelerate properly from there (confirmed this today by continuing to accelerate once I got into 2nd, made it to about 70MPH with ~6000RPM).

Reverse functions normally.

I've yet to go through the wiring again, but that's first on the to-do list along with a fluid/filter change. Does anyone have any idea what's going on? This is the last step in getting my swap daily driveable, and after a year of sitting it's time. If anyone has any ideas or things I should check for, please share, I'd greatly appreciate it.

ZTwentyAteU

iTrader: (12)

sounds to me like the trans is toast. What you describe is a common problem

Jays_SSZ28

iTrader: (2)

What engine computer is controlling this?

bprzybyl

iTrader: (3)

Really hope it's not toast but it's really looking that way.

PCM is from a 5.3l/4L60E Silverado (original PCM died, purchased another from a junkyard). It than had VATS tuned out and some minor changes to the cooling fan temps.

also, what could be failed? Is it something that would be fixed with a rebuild similar to the Basement 4l60e buildup did?

Thanks for the help so far guys, really appreciate it

ZTwentyAteU

iTrader: (12)

don't quote me on it, but usually a clip/ring wears down and breaks, something happens wirh the drum, and then the clutch packs usually burn up to nothing. Again i'm not auto trans builder so I could be wrong on the failure.

I've had it happen more times than I want to say. lol


first..second...then third is like a neutral right?

bprzybyl

iTrader: (3)

Yeah, the more I think about it, it seems to be that it shifts fine from first to second, then shifts to third and it feels the same as neutral.

At this point I'm starting to weigh out my options, as far as rebuild myself, have it rebuilt, or buy another junkyard tranny (though right now they're 0-1). It seems at this point this trans is shot, but I wanna wait until I get the pan off before I make a final decision.

I never mentioned before, but this transmission had only 60,000 miles on it. But I got it for about half what other junkyards were asking, so maybe there was a reason.

Jays_SSZ28

iTrader: (2)

Unplug the electrical connector and try to drive it. With it unplugged it will be in 3rd and max line pressure.

bprzybyl

iTrader: (3)

So unplug the connector then shift in to overdrive as usual? Or will I only have 3rd no matter what I do?

ArkBird96

Unplugging the electrical connector does 2 things. It's called Limp Mode. The first thing it does is to hold the trans in 3rd gear unless the shifter is in manual 2. Putting the shifter in 2nd forces it into 2nd. So for this test, make sure you have it in OD. It also defaults to max line pressure, so there's an outside chance that the 3-4 clutch pack would grab just a little.

From what you're describing, it sounds like your 3-4 clutch pack is toast and the trans will have to be rebuilt or replaced.

bprzybyl

iTrader: (3)

So I finally wasn't working 16 hour days at work, and had a chance to pop off the trans connector. Here's the results-

Put it in reverse, the car reversed fine.

Put it in drive, it moved forward! It seemed to hold the gear really well once it got moving, but things were not as they should be at all. 2000RPM would get me about 15mph, and didn't seem to be slipping. 3000RPM got me up into the 20's. I don't think my car got much over 30mph, even with the engine at 6000RPM. Anything above 30MPH or 3000RPM and the trans felt like it was in neutral.

Now that I think of it, shoulda put it in 2 and saw how things worked. Does this all sound like a burned 3-4 clutch?

I've been researching the parts necessary for a rebuild, and If someone here can support that this proves it's not an electrical problem and that the trans is in fact in need of repair, I'm going to rebuild it myself. If I do, it will be with the K19 rebuild kit from PATC (red alto clutches & kolene steels, bunch of other minor upgrades) and a beast sunshell. I figured if I'm doing this anyway, I might as well pick up a new torque converter, and I still have to call Circle D to verify but their 278mm $400 converter seems to fit the bill. If I rebuild myself, I'll have a better transmission for less than the cost of a normal rebuild locally.

So does it sound like a bad 3-4? I also wanted to thank everyone for their help thus far, you guys have made a bad problem which I have little expertise in something I can handle.

Jays_SSZ28

iTrader: (2)

You've got a ton of options.

Heres just one.
Take it apart and inspect it until you find a problem, rebuild it.
If you didn't find a problem you may have the same issues when it goes back in fully built.


Yes it does sound like a common symptom of bad 3-4 clutches, but I also question the PCM, why one fried, and how I've seen junkyards, etc just hand out PCM's for any application and say to have it flashed at autozone or a dealer when neither say they can do it.

Did you verify the PCM number and letter code? And do you know why the old one fried?

bprzybyl

iTrader: (3)

I have no clue why the original pcm was bad. It would still kick the fuel pump relay but wouldn't run the car because it didn't have VATS removed. The problem with it was that when I tried to hook up to it through the OBDII port (and HPTuners at the tuner as well) it wouldn't connect. The new PCM is from a good junkyard and the part should be from the vehicle they said it was (2005 Silverado with Automatic Trans). The numbers on the new PCM match those on the old PCM.

I'm going to order the technicalvideos.com 4L60E rebuild video and ATSG 4L60E manual and see what I'm getting into before I order any transmission parts.

Does anyone think there would be any value in replacing the filter and fluid at this point? I already bought the filter & gasket kit from GM, but that could just be used with the rebuilt unit. It'd be another 10+ quarts of fluid on top of that (Large torque converter, cooler, deep pan).

I do plan on dropping the pan anyway to see if there's anything obvious going on.

ZTwentyAteU

iTrader: (12)

I'd drain it and see if it had black in it from the clutch packs. Having tried the change fluid method a few times with no success, I wouldnt waste my $ on 11 more quarts.

Take her apart and see the damage. It sounds just like the common 4l60bs. Also, may check the shift solenoids, you can get to them with the pan off. They have been known to cause problems, but it should throw a code for it. usually if that went bad it took other things with it though.

sorry to hear your bad luck

bprzybyl

iTrader: (3)

Well, sorry to waste everyone's time. Discovered the problem. No transmission filter. It had a new pan gasket on it and the guy said it was drained (deep pan, has a drain plug). I never checked it and assume all was fine in the trans. Literally 10 minutes worth of time with the engine out and hanging on the hoist. Here's the pan with all the fluid emptied-

Feel free to call me ignorant, I'm kicking myself as it is.

If I could bother you guys with a couple final questions-
1 - Can I still use the hard parts? I'm going to replace the torque converter, and if possible rebuild the transmission. But since the filter wasn't there, I'm worried all that **** wandering around in the trans would cause problems.

2 - Assuming the trans can't be re-used, how old of a trans can I use? Can I just go back to 1997? It seems like the only limiting factor is a PWM pressure regulator.

Thanks for all your help everyone, assuming I can re-use this transmission, expect a rebuild thread.