Won't downshift in 4th over 60 MPH -- FIXED!!!
 

Built tranny, no problems until the shifter cable broke a couple weeks ago. Finally got around to replacing the cable yesterday, and now the tranny acts fine up until 60 MPH (will kick down like it always did below 60 MPH) but will NOT kick down above 60 MPH with the selector in OD, no matter what I do. I can manually select 1, 2, 3, 4, N, R, and Park, so I don't think the shifter cable is out of alignment. I tried re-loading my LS1_Edit file on the off chance that it somehow got corrupted, but no change after doing that.

Any suggestions? I have AutoTap... Is there some way of watching what the shift solenoids are doing? (Solenoid A Performance? Solenoid B Performance?) Or should I focus on the shifter cable? (To set it, I put the selector in Park, put the tranny in Park, and locked the cable adjuster down where it stood.)

Any help is appreciated.

You can go under the car and disconnect the cable. Then manually set the trans selector in OD, with no cable. Just make sure you have your foot on the brake when you start it ;)

Then take the car for a ride and see what happens. That will isolate a cable adjustment problem. I can't see what the hell could be causing that problem though......

Good luck and report back with your findings :)

That's a good idea... I should have thought of that, since that's how I managed to get the car home when the shifter cable broke. (Had to tell my wife, "Okay, now it is REALLY important that you keep your foot on the brake when I'm under the car and I put the car in gear. REALLY, REALLY important! :eek2: )

I'll try it.

Did you follow the manual when you installed the cable. I can't remember the specifics but basically you have release the self tensioner, shift into neutral or park and lock the tensioner. If you don't follow the instructions the transmission won't shift correctly.

Gary

Yes, the tensioner was unlocked. Put Tranny in park, put shifter in park, THEN I locked the tensioner.

will it downshift from 3rd normally?

Downshifts from 3rd and 4th normally at all speeds EXCEPT above 60 MPH. :confused:

Someone suggested altering the "kickdown" points in 4th gear so that it will kick down at, say, 30% throttle, just to see if it isn't really a glitch in the LS1_Edit file... Not sure how that would have happened, but I've heard of it happening with other people's cars. I'll try that tomorrow.

Well, changing the kickdown points with LS1_Edit fixed the problem. I set it so that it will downshift from 4th to 3rd at anything over 56% throttle, and voila! No more downshift problem. :)

So apparently the old LS1_Edit file got corrupted in the PCM somehow, since I've never had and kickdown problems before, and I've been using these same shift tables for 6 months. Weird. Thanks for the suggestions guys. :)

UPDATE: It was mechanical.
 

Just an update here... Turns out it was a mechanical problem, and NOT a corrupted LS1_Edit file.

The car was still acting funny after my prior "fix" (i.e. now it was refusing to upshift at 130 mph :eek: ) so I tried autotapping it with the car not running. Turns out my throttle position sensor was only reading 78% throttle with my foot to the floor. Went under the hood and sure enough, the throttle blade was not opening up all the way, even with the cable pulled all the way to the stop at the round cable connector box. A little investigating revealed a problem at the throttle cable adjuster (near the cowl & firewall). Fixed that, and now I have 100% throttle again, with no more downshifting problems. FINALLY!!!

Great news!! I've heard of others having sudden issues with throttle cables coming out of adjustment (TC/ASR cars only obviously) for no reason. Glad you got it fixed. :cheers:

Well I'll be damned.

The sh*t you DON'T think of, eh?