Thread: Drag racing launching question/problem
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Old Mon, May 10th, 2010, 05:09 PM
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Originally Posted by Pocket View Post
This happened on my old tunes from Jody. With the A/D counts on the throttle at 504 and higher, the 1st gear TC lockup speed was set at 16 mph. Anything below 504 was raised all the way up to 127.5 mph.

If the TC locked up, then it would make sense as to why it lurched forward like it did. So did it shift into 2nd and then lock, or do you think it locked the TC in first while I was spooling up?

I'm still going to try changing that table to see what happens. I might do it on my old tune to see if it makes a difference. I know how to duplicate the launch problem... just hold 1800+ RPM for longer than about 5-6 seconds.
Curtis,

It's impossible to say what is actually going on...and it can even be so stupid as a mechanical transmission issue where the pump isn't supplying enough fluid under that load (since it's raised to such a high pressure under WOT in 1st) to hold the torque converter clutch off of the backing plate.

I'd put a scanner on it and see what is being commanded.
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Tuning, PCM flashing, and burning chips for 7.3s since 2008. Repairing all aspects of 7.3L Powerstrokes for 25 years.
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