pittman

iTrader: (1)

have any of you ever heard of this happening before ? My tranny is a 2003 and the PCM is a year 2000.

Just @ the track with refreshed Trans and new TC . Just added a new B&M shift kit (no kit before). The TC changed from a 10.5" to 9.5" (both were YANK 3600's).

Launching and viewing in HPT primary table\graph...it left the line in 1st gear till it hit 8 mph, then shifted to 2nd and stayed till it hit 28 mph, next it downshifted back to 1st till 58 mph @6400rpm, shifted hard and ran fine the rest of the track.

Something told the tranny to shift to 2nd at only 8 mph. I had a pretty good tuner with me and he could not figure out what the heck. Maybe a line pressure thing ? No real changes except for the shift kit.

Anyone have a clue ???

Pitt

carlsonauto

Thats interesting.... Were you datalogging? Did you by chance get it on the log?? Im curious to know what is causing it, wether its being commanded by the pcm or something goofy going on internal trans.

mrvedit

Very strange indeed.

This sounds slightly similar to something RonNovaSS emailed me months ago when he could not get his shift points correct and logging sometimes even failed.
IIRC, he cleaned various ground connections on his C5 Vette and everthing worked after that.

I have also seen various "Abuse" settings in the trans section of HPT. I turn them all off.
I wonder if your traction control got confused; is it enabled?

pittman

iTrader: (1)

I did log 3 runs with HPT. This is my Silverado with a 402 stroker, not my vette. Can I send to you by email ?

I talked to Ron today and he hasn't a clue either.

No traction control because it is a 2000 Silverado. It is driving me crazy. Everything was fine and dialed in till I refreshed the tranny with a shift kit and 3-4 clutch pack.

pittman

iTrader: (1)

I lost 2.5 tenths on my sixty foot and a full second in the 1/4 also was down 8 mph.

mrvedit

Both shift solenoids are energized for 1st gear. If solenoid A had an intermittent connection (bad connection, broken wire) it could result in the symptom you had.
You might consider replacing the solenoid and the internal harness.

You can log the PCM commands to the trans. Since the 2000 PCM doesn't allow many "bits" of logged data, you may have to create a special CFG file with mostly trans related parameters.

pittman

iTrader: (1)

Thanks man

RonSSNova

iTrader: (3)

I think I'd be tempted to remove the big connector from the trans. If you have some contact cleaner, spray the socket and connector good then mate and un mate several times.
You mentioned in your PM that it works fine on the street. So it sort of leads me to believe the G force from the launch....er semi launch is maybe making something go intermittant????
Might also check that big cable and make sure it's free and not pinched somewhere.
Shifter cable adjusted well?
If all that proves ok, then pull the pan and check the internal wires. They would have been removed when pulling the VB.

What does it do if you hammer it on the street? Other than blow the tires off that is?

Ron

08GXPLS4

Is the fluid level full? I have had some drag car transmissions do weird things being little low of fluid . Did u change filter or pan? Make sure filter has good seal and no cracks in the neck .Sometimes on a hard launch it will starve for oil u can over fill it to see if problem goes away.

pittman

iTrader: (1)

Seems fine during normal driving. After breaking the TC in with 120+ miles, I only hammered it once on the street from 55 mph. It down shifted and just lit the tires up so I let off at 65 mph from tire spin.
Thanks for the ideas, I will start checking things out.


Yeah it is full. I checked that right away since the tranny was new/rebuilt.