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More on PCM upgrade - Help Needed!

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Hi again - I'm the one with the 96 5.9L Turbo 4x4 that had the PCM upgrade to correct a gear hunting issue. The dealership assured us that no degradation in fuel mileage would occur. However, after the upgrade the truck now runs at a higher RPM and the fuel mileage went down from 17 to 15 unloaded and from 13 to 10.5 when pulling a trailer. I use this truck for my work and it is going to cost me an estimated $3,700 over then next 100k miles assuming fuel averages $3.00/gallon over that time. The truck use to just purr going down the freeway at 70mph and it always felt like you were going around 20 mph slower than you were. This really did happen and now I need to know what to do to fix it. What about an after market chip?? One of the mechanics at the dealership admitted that this could happen in theory, but they are unwilling to help us! Any recommendations are greatly appreciated!
Thanks, Laurie (Wesley's girlfriend)
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Chips don't work on a 12 valve, they're all mechanical.
That's why the PCM flash can't have changed the way the engine runs.
My bet the problem is with the tranny programing.
People with '96s often get the flash done in order to use a tranny lockup switch.
'96 is the only year that won't work without the flash.
Perhaps you should hook up an easy and cheap to do lockup switch.
Instructions> http://www.tstproducts.com/Torque Converter Lockup Switch.pdf
 

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Discussion Starter · #3 ·
Tranny programming

Yes - it definitely is something to do with the tranny programming since that is what the pcm was suppose to address. It use to run at 1500 rpms when going 70 mph - now it's at around 1800 rpms and I'm not sure if it really is kicking into overdrive... (forgive me - I'm not mechanically inclined) Does this switch push the truck into overdrive? Thanks again for your help - Laurie
 

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You have another issue Dodge has no flash that will eliminate overdrive..............
 

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Drive the truck with a scanner in monitor mode you will be able to see why you are not getting o/d
 
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