Hard shifting, check engine???
Thread Starter
Instructor
Joined: Apr 2004
Posts: 145
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From: Sunny SoCal
Hard shifting, check engine???
Recently replaced 2.73 with 3.42 and had a Pred tune. Now 2004 C5 is shifting hard and chk engine light is on. After car sits for awhile the shifting is smooth again. Is this a tune issue, trans issue, or gear issue? Also what is trans fluid normal temp at freeway speeds? Thanks a ton!
Burning Brakes
Joined: Jun 2002
Posts: 996
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From: Frisco Texas
Originally Posted by OBSESDD
Recently replaced 2.73 with 3.42 and had a Pred tune. Now 2004 C5 is shifting hard and chk engine light is on. After car sits for awhile the shifting is smooth again. Is this a tune issue, trans issue, or gear issue? Also what is trans fluid normal temp at freeway speeds? Thanks a ton!
Thread Starter
Instructor
Joined: Apr 2004
Posts: 145
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From: Sunny SoCal
Originally Posted by cscollis
Did you raise the line presure with the pred? This will cause the hard shifts. Tranny should be below 200.
Safety Car
Joined: Aug 2000
Posts: 4,154
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From: Murphy TX
Cruise-In II Veteran
What codes are set? If the CEL is on, you should have some DTCs set. Many of the tranny codes will trigger very firm shifts, so it could well be the result of a code rather than the cause of one. When did the new behaviors (CEL, firm shifting, etc.) start? Your nominal trans fluid temperature will depend a lot on what your fan programming is (and whether or not you have an aux cooler or not.)
Thread Starter
Instructor
Joined: Apr 2004
Posts: 145
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From: Sunny SoCal
Originally Posted by ToplessTexan
What codes are set? If the CEL is on, you should have some DTCs set. Many of the tranny codes will trigger very firm shifts, so it could well be the result of a code rather than the cause of one. When did the new behaviors (CEL, firm shifting, etc.) start? Your nominal trans fluid temperature will depend a lot on what your fan programming is (and whether or not you have an aux cooler or not.)
Safety Car
Joined: Aug 2000
Posts: 4,154
Likes: 1
From: Murphy TX
Cruise-In II Veteran
Originally Posted by OBSESDD
Again I dont know what the settings are, (I have a call into the programmer). This problem just started although I've driven the car very EZ breaking in the new gears.
https://www.corvetteforum.com/techti...D=26&TopicID=1
Given that it didn't start right away and seems to come and go, I'd lean away from thinking the line pressure was too high and more toward a gear-related programming issue. Codes will tell us more.
I haven't been keeping up with the Predator, you might post in Scan & Tune and see if anybody is aware of any known issues with your combo.
Melting Slicks
Joined: Feb 2002
Posts: 2,613
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From: Winston Salem NC
Originally Posted by Dirty Howie
It needs to be properly programed after the gear swap. Otherwize the computer will see excessive slippage and put the tranny in safe mode......which gives hard shifts.
I had this problem......
DH
I had this problem......
DH
Sounds just like this is it.
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