Problem with 4 o/d lockup, need the other Pro's

[BR3W CITY]

**This will be detailed, and long, so I'm gonna put a warning that if you don't want to read the whole thing, skip ahead to the bottom....but don't ask me something that was explained in the body **

Alright my seasoned LS brethren, we've got an issue that is causing head scratching among us. My 4th gear lockup is doing something that I can't figure out, and the data logs are just as confusing.

Backstory; Truck started its build in 09, I had a "real" job (you know, taxes, having to show up etc). Had never built an O/D auto before, always just ordered a convertor online and tossed in behind a junkyard tranny. Got a referral to All World Trans in Waukesha WI from a local bracket racer. Gave them a good core, had them do a full rebuild w o.e. parts. Debated going with the HD2 upgrade, but they didn't want to use parts they didn't source. Was told the solenoids were replaced with the o.e. master kit.
Thats all fine, but I made the first mistake, an error of omission; I allowed them to source and spec a convertor. I didn't really notice until WELL after that, that I don't have a freaking CLUE what its stall speed is.

Fast forward a month or two of build-progress. Everything is installed, truck runs and I take it for tuning. Whole setup (from cam to trans) had ~250mi of break-in. The tuner (who I'll refer to as "a$$hole") apparently locks the TCC in 3rd to boost the output #'s....like you would when trying to load up a diesel for torque spike. Noticed some weird lockup timing on the road test, and made a small adjustment to the misfire detection to prevent false knock from unlocking the convertor. Seemed good enough, and I was jacked to drive it.

Fast forward again; no normal job, spend 80% of my time building/fixing/tuning cars. Cut old tuner loose after finding tons of errors in his tune. Switch over to SD, dial it in pretty good. After 4 hours of tuning, and data logging, and tweaking, we still have this weird problem.

Problem: The shift up to 4th is just fine, but the application of o/d is really odd. It shifts to 4th, then goes to lock....applies lock but then momentarily releases it...and then re-engages locked. WTF? On the data, it looks like I'm lifting off the throttle, but I'm not.

Normally, each shift and lock point can be seen easily on the engine speed graph, by following the drop in rpm's (linear plane, unchanging load). In this case, the 4-o/d is a sudden falloff....almost like you bumped the clutch accidentally on a manual car.

So WTF is this? Nothing in our tune suggests a problem, and we've tried a base-calibrated trans table as well as our performance-changed one. There are no leaks, fluid and filter are fresh. I haven't seen anyone else describing a similar issue, at least not the way I picture it. Our only thoughts are that; something is wrong internally with the convertor, the TCC solenoid is wonky, or something in my tcc wiring is weird. None seem to fit the bill exactly, but I'm at a loss.

[Jon01]

Are you logging TCC voltage?

[BR3W CITY]

Not yet, it was like 1am, the neighbors were less than thrilled about any more "passes" through the neighborhood lol. The cal looks fine, so it seems like we're chasing a mechanical problem.

Can a TCC solenoid only "kinda" fail?

[Jon01]

Yeah, they get crabby sometimes.

I'd log tcc voltage and make sure it's applying 12v…you never know.

I've never seen a solenoid fail…it works or it doesn't kinda thing.

[BR3W CITY]

Thats what I thought too, hence the weirdness about the "partial" failure. Once it locks, its pretty solid.

I am noticing that I'm turning higher rpm's than I thought I should be on an 80e/3:73/28" tire.

[clinebarger]

Are there any P18XX codes turned "off" in your tune? Some of these are Trans component performance codes.
Any P07XX codes turned "off"?

The TCC solenoid in a 4L80E IS NOT "On/Off", It is controlled via Pulse Width Modulation, The PCM ramps up & down the Amperage that the Solenoid can draw.

This can be seen as TCC Duty Cycle, Read in percentage (0-100%) on a scan tool, 0% is unlocked, 90-100% is full lock-up....In between is the ramp up between unlock & locked.

Gain access to the Trans Functional Test, Select PWM TCC Solenoid control.
Play with this control to replicate the issue, If it still does the Lock-Unlock-Lock symptom, Most likely a Electrical/Solenoid/Mechanical failure, If not.....Maybe a tune issue.

While commanding 100% lock-up, The TCC Slip value (read in RPM) should be below 30 RPM.

[solidaxel]

Originally Posted by clinebarger

Are there any P18XX codes turned "off" in your tune? Some of these are Trans component performance codes.
Any P07XX codes turned "off"?

The TCC solenoid in a 4L80E IS NOT "On/Off", It is controlled via Pulse Width Modulation, The PCM ramps up & down the Amperage that the Solenoid can draw.

This can be seen as TCC Duty Cycle, Read in percentage (0-100%) on a scan tool, 0% is unlocked, 90-100% is full lock-up....In between is the ramp up between unlock & locked.

Gain access to the Trans Functional Test, Select PWM TCC Solenoid control.
Play with this control to replicate the issue, If it still does the Lock-Unlock-Lock symptom, Most likely a Electrical/Solenoid/Mechanical failure, If not.....Maybe a tune issue.

While commanding 100% lock-up, The TCC Slip value (read in RPM) should be below 30 RPM.

This site never fails to educate me!!!
Now just remember it!

[68c10airstream]

Hey br3w city, if you have access to a good dvom, probe the tps reference line that goes back to the pcm (varying voltage with varying throttle). You can do this test key on/ engine off. Turn the dvom to dc heartz scale and look for alot of activity on line just off idle. My fluke meter samples 40 times a second and shows this as a needle running across a scale from side to side and also displays the value as you go. The beauty of the scale is you can see the increase of heartz activity as the needle jumps around to a higher value. The highest wear area in a tps is just off idle, and taking off from a stop sign you quickly go past this area, where as during light throttle lock up you hang in this delicate area longer. If you are running a cold thermostat that maybe leaks a little past it you drop down into a non permissive area of temp and programming says no go. Living up north i fixed many lock up torque converters that hunted around a lot by replacing the thermostat. I think that possibly in the trans info side of the pcm it would say lock up or unlock as a commanded state, if so it would be a good place to look to see if the pcm is commanding it on or not. If you had access to a grafing multi meter like a snap on vantage you could look at the voltage spike that is on line when it is turned off. A 12 volt solenoid can easily put a 20-50 volt spike on line after shut off. The spike should be the same value all the time, not all over the place. I have checked the resistance of solenoids and check out fine but in use the spike is inconsistent. In the 90's found mant 2.3 4 cylinder mercury topaz/ ford ?? that would misfire, shut down, run like crap. A single fuel injector for all 4 cylinders. I could lab trace the injector induced spike and tell you if it was a bad injector or a bad engine controller by the image. Low spike and dropped off, bad injector, high spike but that spike didn't plateau and hold on then drop off, bad controller. The snap on vantage used on ebay are really cheap and take the info to a whole new level of diagnostics. Good luck, Brian Fuller

[BR3W CITY]

Hey Brian, thanks for the info (but omg use paragraphs, I had to copy that into word to break it up and read it lol).

I've got a couple cheapies, but I'll see if I can borrow my guys Snap-On fancy-o-meter. I can watch TPS voltage in HP Tuners, and we hadn't seen anything weird when watching it live.

Stock tstat, and we have our tables set/populated down to 20*F, which is well below anything the truck would ever be allowed to see.

It doesn't hunt at all, and seems to have no problem maintaining and releasing lock on command. You can be locked, pass someone, and re-lock with seeming normality. Its just during the 3-4-lock sequence that it does the weird "juke". We can actively monitor lockup state, and have verified that it does command lockup.

I will try to look at the voltage spike.


Cline- We'll be putting HPT back into it this weekend and I'll doublecheck that the trans codes haven't been disabled. iirc we set them all back to the default "report" settings, but I'll have a look.

Do you know if the Functionality test can be accessed through a Tuner? Or is it something that has to be done through a Dealer scanner Startach/TechII type deal?

[akdg87]

What year is the 4l80e that you are using? I know early models were just on/off TCC lockup as opposed to the pwm lockup in the later year models. Is it possible your builder used an on/off solenoid instead of the pwm one?

Also did you set the MAF to fail properly so it goes into SD?

[BR3W CITY]

Originally Posted by akdg87

What year is the 4l80e that you are using? I know early models were just on/off TCC lockup as opposed to the pwm lockup in the later year models. Is it possible your builder used an on/off solenoid instead of the pwm one?

Also did you set the MAF to fail properly so it goes into SD?

Trans was iirc a 97. I think its the early 92-93 that had the other setup, but I may be wrong. Not sure how to check that? I assume I'd have to drop the pan to see what solenoid they put in.

MAF fail is correct. This problem actually occured before AND after the entire OS swap.

[clinebarger]

Originally Posted by BR3W CITY

Cline- We'll be putting HPT back into it this weekend and I'll doublecheck that the trans codes haven't been disabled. iirc we set them all back to the default "report" settings, but I'll have a look.

Do you know if the Functionality test can be accessed through a Tuner? Or is it something that has to be done through a Dealer scanner Startach/TechII type deal?

You can access the functional test through the HPT VCM scanner, Click Displays, Click VCM controls in the drop down, Then Trans.

This pic is from my HPT VCM scanner for a 4L60E, 4L60E has a TCC solenoid & a TCC PWM solenoid. A 4L80E will just show the TCC PWM solenoid, You can select the Duty Cycle & then toggle it off & on.

[akdg87]

id say get on the HP tuners forum then post your datalog and tune files, those guys over there are pretty sharp.