2nd to 3rd shift problem please help
01-20-2008, 11:44 PM
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2nd to 3rd shift problem please help Let me start off by telling you a little about my car and mods that way you know what Im working on. I have a 00 trans am with some mild mods. Diablosport tuner,lt’s,ory,MS3 cam, 4000 stall fuddle, 3.73 gears, rebuilt tranny when I go to the track I spray it a little. Now on to the problem that I’ve had that is driving me crazy.
When Im at the track or any time Im running the car full throttle it will not shift from 2nd to 3rd. What happens is it will just bounce off the rev limiter until I let off the gas then it will shift from 2nd to 3rd. I had a few people tell me that it could be the tranny and with 68,xxx miles I figured that it couldn’t hurt to have it rebuilt to with stand the higher horsepower levels that the car now has. But the car still has the same problem as before the rebuild. I’ve always replaced the fluid every few months and make sure that it is topped off. Is there any way this can be a converter problem. I’ve had the converter unlock on me last year when I was going up a hill then it relock but I’ve never had that problem since. I don’t drive this car in the fall or winter but would really like to have it out and racing this spring. If you need any more info please ask me. Thanks in advance to anyone that helps me out with this problem.
When Im at the track or any time Im running the car full throttle it will not shift from 2nd to 3rd. What happens is it will just bounce off the rev limiter until I let off the gas then it will shift from 2nd to 3rd. I had a few people tell me that it could be the tranny and with 68,xxx miles I figured that it couldn’t hurt to have it rebuilt to with stand the higher horsepower levels that the car now has. But the car still has the same problem as before the rebuild. I’ve always replaced the fluid every few months and make sure that it is topped off. Is there any way this can be a converter problem. I’ve had the converter unlock on me last year when I was going up a hill then it relock but I’ve never had that problem since. I don’t drive this car in the fall or winter but would really like to have it out and racing this spring. If you need any more info please ask me. Thanks in advance to anyone that helps me out with this problem. 
01-21-2008, 07:43 AM
#2
Sounds like your issue might be in the tune of the vehicle. Not familiar with the diablo software but the shift rpms and the mph tables need to be lowered. Also in some case the rev limiter needs to be raised. Is the tuning software have the proper gear ratio and tire size programed in? If not start there. Good luck. Vince
01-21-2008, 03:38 PM
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I dont have the car tuned for the tire size and gear ratio. I will see what the tables are set at and try to lower them some and see if that helps. Any idea of what mph and rpm they should be set at for my set up?
01-22-2008, 05:29 AM
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One of the best tuners here in Aus has a similar prob with a customers' car. He will get it spot on and then a variable will change that he didn't anticipate and the thing won't shift the 2-3 reliably.
http://www.youtube.com/watch?v=aGlvF...eature=related
This thing is a M90 L67 pulling 12.3 all day every day with this fault.
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01-22-2008, 09:08 AM
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Well even though the milage on the trans is not that high , It is possible you have excessive 3-4 clutch clearance, Some cars go 200000 miles without and isue but others are not so lucky. I would go into the tune and allow at least 500 RPM between the comanded 2-3 shift and the rev limiter and lower the MPH way down. Then monitor the data stream with a scanner or tuner and try it , If you see the comand happen at the specified RPM and theshift does not occu before the rev limiter then I would say you are in need of a trans, The big thing is to determine the shift was indeed comanded, IMO
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01-22-2008, 04:05 PM
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I will try that and see if it works. We have snow on the ground out here so it will be a little while before I can test drive it. Thanks for the advice. Performa Build do you build th400 by any chance? Im planning on putting in a TH 400 if this tranny is bad.
