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Discussion Starter #1
My gf's car is search shifting. After thinking it was the tranny, we had it replaced twice to have nothing good come out of it. It is still doing it and I cannot figure out why. Any ideas?
 

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First of all, what the hell do you mean by "search shifting?" And secondly, why wouldn't you diagnose the problem first before putting two trannies into it? Or pay a reputable shop to diagnose it for you?
 

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Bad speed sensor maybe.

Any other symptoms, like the cruise control randomly droppng out, or not setting, or maybe ABS codes set, or the ABS system acting out????

If so, hook up a scantool that can read PID's & set it up to monitor the speed sensors output PID to the computer, while someone drives & the shifting is acting up & see if you can catch the speed sensors output acting out.
 

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Discussion Starter #4
QUOTE (Nidan @ Mar 14 2009, 10:38 PM) index.php?act=findpost&pid=708649
First of all, what the hell do you mean by "search shifting?" And secondly, why wouldn't you diagnose the problem first before putting two trannies into it? Or pay a reputable shop to diagnose it for you?[/b]
We did have a shop do it and by search shifting, I mean it will change gears when it doesn't need to and it will go into the wrong gears.

As for the code thing I had it hooked up and the only code it was throwing was for something not related at all to this problem. There were no transmission codes thrown or anything from the VSS.
 

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Well the computer tells the tranny when to shift & what gear to use, so if the computer is screwed up, or if the PID's it uses to decide what & when to have the tranny do it's thing, are screwed up, then the computer can get confused about what to have the tranny do, sorta like me sometimes!!!! lol

So maybe it's time to have the computer checked out, or reflashed.

What event preceeded it beginning to do this????
 

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Discussion Starter #6
QUOTE (pawpaw @ Mar 15 2009, 10:46 PM) index.php?act=findpost&pid=709049
Well the computer tells the tranny when to shift & what gear to use, so if the computer is screwed up, or if the PID's it uses to decide what & when to have the tranny do it's thing, are screwed up, then the computer can get confused about what to have the tranny do, sorta like me sometimes!!!! lol

So maybe it's time to have the computer checked out, or reflashed.

What event preceeded it beginning to do this????[/b]
Dunno, she got it before she got me. How hard and how much would it cost to get the computer re-flashed? I am assuming that I'd have to go to the dealership to get it re-flashed?
 

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Well call the Dealer, give him the symptoms, what you've done so far & see what he thinks about reflashing the computer.

Could be the computer is messed up, could be that some sensors PID's it uses to control shifting are corrupt, could be the computers output to the tranny is corrupt.

Lots of unknowns still. So find out from the GF what event preceeded it's beginning to act out

Has the tranny computer been scanned for trouble codes???? If not, maybe begin there & see if any good clues turn up.

What was the engine trouble code number that was found when it was scanned????

More thoughts for consideration.
Let us know what you find.
 

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Reflashing the PCM isn't likely to help, if there is even an update available for the car. The problem may not necessarily be in the transmission, altho it likely is. However, as Pawpaw stated, there are many different parameters that affect shifting, and a problem with the engine could cause the car to shift improperly. The code you got may be related to the actual root cause, even tho it may not seem that way, so if you can let us know what the code was, it might help.

Does the speedometer work properly, or does it cut in and out at all when the tranny is wanting to shift? It could also be an MLP problem - if the MLP reads wrong, it could make the PCM think you have a different gear range selected than you do, causing shift problems.
 

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Discussion Starter #9
The code was for an airflow meter or something like that. I can double check if I can perform a check at home with out the little computers.
 

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QUOTE (Naemion @ Mar 21 2009, 05:56 PM) index.php?act=findpost&pid=710972
The code was for an airflow meter or something like that. I can double check if I can perform a check at home with out the little computers.[/b]
You'll need a scantool, or code reader, to pull the code, or run it by your favorite autoparts store, but it sounds like maybe it was a MAF sensor code.

Did you do anything about it????

If not & it was a MAF sensor code, maybe all you need to do is pull the MAF sensor & carefully clean it with a non residual spray cleaner, formulated especially for cleaning MAF sensors, maybe something like CRC MAF Sensor Cleaner, You can find it at Wallyworld!!!!

Then look upstream to find out why the MAF sensor got dirty.

A messed up MAF sensor PID to the computer can cause driveability problems.

Anyway, if you can remember the code, or better yet, have the computer rescanned & post ALL of the code numbers found, it might yield some good clues for the diagnosis.
 

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My car started doing this yesterday (97 vulcan) I would get on the hwy at about 80-85mph and the car would jump from 2K RPM to 4K RPM and decide to go back down to 2K and randomly jump back up to 4K... Codes scanned and came to a P0401, so I changed the DPFE sensor again and now it's fine. Maybe check your DPFE or EGR sensors.

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Discussion Starter #12
Yeah, it was the MAF sensor now I remember. But why would that cause it to shift around when it isn't supposed to?
 
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