Downshift is chattering my teeth

[buzzinghalfdozen24]

Built, 48re is downshifting very harsh from, I believe, 2nd-1st gears. Build has had over 30k miles and has performed flawlessly. Withing the last two weeks the problems has started and gotten almost 100% consistent. Nearly every time I slow down or come to a stop, the trans downshifts really harsh. Harsh enough I don't want to drive it to risk damaging something. It's not a "common clunking", it's gotta be more than that.

I adjusted the bands and it made no difference. The only "routine" thing that I haven't done is do a system flush. However, I sent in an oil sample through my work, and it was clean as a whistle. I don't think this would equate to causing this, but who know, simple stuff sometimes is just that, simple.

I'm looking for advice, or suggestions. I've thought about pressure sensors, timing sensors, etc... but have no way of testing. Pry taking it to my local, trusted, transmission shop for troubleshooting tomorrow.

 

[cerberusiam]

Gov pressure transdcuer and solenoid is the first place to start looking for issues. The TTVA hanging high can also cause that. Not much you can do without a scanner that will read pressures and gauges on the trans.

 

[buzzinghalfdozen24]

I called Goerend today and talked to jeff and dave. Dave's first suggestion was regarding the TTVA. He told me to first "disconnect" it. And drive truck without it hooked up, up to 30mph, and then slow down again. If it doesn't do it, then problem is the TTVA. I wasn't sure if he meant electrically disconnect it, but found out if it's unplugged, the truck won't start because it can't sense neutral. I didn't have time to remove the TTVA, but I imagine that would be a good option.

I'm going to start with the basics tomorrow morning. I have been behind of doing a transmission service, so I am going to do a flush/filter tomorrow morning. Should have that done by noon. But the interesting thing I learned while researching this tonight what listed in the service manual someone posted online. It says to start low on the oil initially when doing a service, and make sure oil is up to operating temperature and in park when checking and adding the oil. Then it says MAKE SURE TO NOT OVERFILL THE OIL LEVEL BECAUSE FOAMING AND IMPROPER SHIFTS MAY OCCUR. This led me to realize about two weeks ago I checked the whole truck over and pulled trans dipstick, oil wasn't on the dipstick, so I added about 1qt. All of this was done with the truck not running. I had a blonde moment, and forgot that that was an incorrect way of checking oil level. So , I'm wondering if I had overfilled the transmission, and this was causing bad shifts. Both the adding oil, and downshift problem may have started at about the same time. I THINK WE HAVE A HOPE NOW!!!!

I've already got the pan drained to do the filter/flush. So, I will correctly do the service and adjust oil level accordingly. I will post if anything is better/worse.

This sound legit, cerberusiam??

 

[cerberusiam]

You need to check the oil level hot idling first and make sure where it is at. If it is low that could be your shifting problem. I generally run 2 quarts over full and the only issue I see is if it is a little over full it will some times spit some fluid out of the breather if I work it hard. Have never seen a shifting problem when it is over full.

I think you unplugged the range sensor not the TTVA motor if you lost the PRNDL display. The TTVA motor has to be unbolted form the trans and rotated away to even get to the plug on it and normally you end up pulling up off the TV shaft and dropping it down so you can see the plug to figure out how to uplug it. It has a locking tab thne you have to push in the right spot to get it to release. Extrremly har dto do when it is place. Might as well take it off and try a test drive. You will get codes but not sure if the trans will go into limp mode. It will definitely shift weird.

Have you checked for codes with the key trick?

 

[buzzinghalfdozen24]

My memory is officially rebooted now. Yes, I did that TTVA thing wrong. I definitely unhooked range sensor. TTVA is that pita thing, that you fight getting connected, lined up, and bolted up! And I didn't do the (3x)key thing, but bully dog gt read no codes.

Thanks for the help

 

[buzzinghalfdozen24]

update... I flushed it, used about 20qts total, carefully added oil at op. temp until level was perfect. Test drives were flawless. Downshifts were perfect, and never jolted one time. I should add this was with my bully dog gt removed. I say this because after 20 mins of testing, and no issues, I pulled over and reinstalled the tunes. Then test drove, and issues returned. Pulled over, removed b.d. and tested again. Issues still remained.

At this point I'm still not sure that the new bully dog update 1.1.5.1 couldn't be part of the problem. I reflashed with the latest version about the same time as mentioned above, fluid level checked (incorrectly), and about the same time the issues began. So, still something to consider.

Next, I did the steps Goerend told me to do, the correct way. I removed the TTVA from the transmission. I checked the electrical connector and it was clean and it good shape, and I plugged it back in and left TTVA zip ty'd up to the transmission. Drove truck as instucted, up to 30 mph and back down, again and again. Truck never bobbled once. I will mention that I noticed a difference in shifting or converter action when accelerating hard. But the downshifts were smooth as ice!! I tested this several times around the block, perfect everytime. So, I reconnected the TTVA and let it calibrate for 60 seconds before starting the truck. Went out and tested again. This time the problem stayed away. And hasnt returned. I have a 30 min trip tonight and I'm going to drive in stock mode to the destination and see how it is. If it's perfect the whole time. When I leave I will add my BD tunes back on and see if it returns. Hopefully not. So... at this point I'm considering 1.)The TTVA may have needed calibrated correctly. 2.) The TTVA is at fault. 3.) The newly updated BD file could have a glitch.

Lots to consider yet, but at least I'm gaining ground. Or I could be totally off, yet, haha. At least I have a fresh trans flush!!

 

[cerberusiam]

Sometimes a reboot fixes all the problems.

 

[buzzinghalfdozen24]

True. Just hope it stays away. Put the tune back on it, and so far so good.